Lighting Guide 5:
Lighting for education
The Society of
Light and Lighting
222 Balham High Road, London SW12 9BS, UK
Tel: 020 8675 5211. Fax: 020 8673 3302. e-mail: sll@cibse.org. www.sll.org.uk
The Society of Light and Lighting is part of the Chartered Institution of Building Services Engineers
This document is based on the best knowledge available at the time of
publication. However, no responsibility of any kind for any injury, death, loss,
damage or delay however caused resulting from the use of these recommendations can be accepted by the Chartered Institution of Building Services
Engineers, the Society of Light and Lighting, the authors or others involved in
its publication. In adopting these recommendations for use each adopter by
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indemnified.
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publisher.
© February 2011 The Society of Light and Lighting
The Society is part of CIBSE which is a registered charity, number 278104.
ISBN 978-1-906846-17-6
Layout and typesetting by CIBSE Publications.
Printed in England by Charlesworth Press, Wakefield, West Yorkshire WF2 9LP
Cover illustrations (clockwise from upper left): Warsaw University (photograph
courtesy of Thorn Lighting); Southwell Minster School, Southwell,
Nottinghamshire (photograph courtesy of Thorn Lighting); Excelsior Academy,
Newcastle Upon Tyne (photograph courtesy of Cundall Light4); Usworth
Sixthform College, Washington, Tyne And Wear (photograph courtesy of Thorn
Lighting).
Note from the publisher
This publication is primarily intended to give guidance. It is not intended to be
exhaustive or definitive, and it will be necessary for users of the guidance given
to exercise their own professional judgement when deciding whether to abide by
or depart from it.
Any commercial products depicted or described within this publication are
included for the purposes of illustration only and their inclusion does not
constitute endorsement or recommendation by the Society.
Printed on recycled paper comprising at least 80% post-consumer waste
Foreword
In 1963 the Illuminating Engineering Society published a remarkable
monograph entitled Lecture theatres and their lighting, which became a standard
work of reference. An updated edition was published in 1973 and then in 1991
it was updated and published as CIBSE Lighting Guide LG5: The visual
environment in lecture, teaching and conference rooms. Within a very short period of
time there were a vast array of CIBSE and Department for Education and
Schools (DfES) guides available covering all manner of lighting in schools,
teaching spaces, lecture theatres and the like, including documents such as
Building Bulletin 90: Lighting design for schools. In 1995 an addendum to LG5
was issued to deal with changes in government funding for schools projects and
changes in European legislation for workplace lighting.
The Department for Children, Schools and Families (previously the
DfES) decided in 2008 that it would join with the SLL in updating LG5 to
include schools.
This Lighting Guide covers not only lecture theatres, but also all
teaching spaces and rooms specific to educational premises across schools and
further education, and extends to committee rooms, conference and multipurpose rooms. It represents a complete revision but includes relevant material
from the original LG5 and BB90 working groups. Our thanks go to many of the
original authors whose work is included here, which include R Aldworth, R
Anderson, J Baker, L Bedocs, R Bell, C Bissell, K Gofton, J Lambert, D Loe, J
Lynes, I MacLean, K Mansfield, J Mardaljevic, M Patel, V Rolfe, P Ruffles, A
Tarrant, R Venning, L Watson and Professor A Wilkins.
LG5 Task Group
I D Macrae (Thorn Lighting) (Chairman)
A Bissell (Cundall LLP)
R Daniels (Department for Education)
B Etayo (Fulcrum First LLP)
S Fotios (Sheffield University)
P Raynam (University College London)
T Ramasoot (Sheffield University)
Director of Information
Jacqueline Balian
Secretary to the Society of Light and Lighting
Liz Peck
Editor
Ken Butcher
Acknowledgement
Permission to reproduce extracts from BS EN 15193, BS EN 12464-2, BS EN
1838 and BS EN 12464-1 (draft) is granted by BSI. British Standards can be
obtained in PDF or hard copy formats from the BSI online shop:
www.bsigroup.com/Shop, or by contacting BSI Customer Services for
hardcopies only: tel: +44 (0)20 8996 9001, e-mail: cservices@bsigroup.com.
Foreword
In 1963 the Illuminating Engineering Society published a remarkable
monograph entitled Lecture theatres and their lighting, which became a standard
work of reference. An updated edition was published in 1973 and then in 1991
it was updated and published as CIBSE Lighting Guide LG5: The visual
environment in lecture, teaching and conference rooms. Within a very short period of
time there were a vast array of CIBSE and Department for Education and
Schools (DfES) guides available covering all manner of lighting in schools,
teaching spaces, lecture theatres and the like, including documents such as
Building Bulletin 90: Lighting design for schools. In 1995 an addendum to LG5
was issued to deal with changes in government funding for schools projects and
changes in European legislation for workplace lighting.
The Department for Children, Schools and Families (previously the
DfES) decided in 2008 that it would join with the SLL in updating LG5 to
include schools.
This Lighting Guide covers not only lecture theatres, but also all
teaching spaces and rooms specific to educational premises across schools and
further education, and extends to committee rooms, conference and multipurpose rooms. It represents a complete revision but includes relevant material
from the original LG5 and BB90 working groups. Our thanks go to many of the
original authors whose work is included here, which include R Aldworth, R
Anderson, J Baker, L Bedocs, R Bell, C Bissell, K Gofton, J Lambert, D Loe, J
Lynes, I MacLean, K Mansfield, J Mardaljevic, M Patel, V Rolfe, P Ruffles, A
Tarrant, R Venning, L Watson and Professor A Wilkins.
LG5 Task Group
I D Macrae (Thorn Lighting) (Chairman)
A Bissell (Cundall LLP)
R Daniels (Department for Education)
B Etayo (Fulcrum First LLP)
S Fotios (Sheffield University)
P Raynam (University College London)
T Ramasoot (Sheffield University)
Director of Information
Jacqueline Balian
Secretary to the Society of Light and Lighting
Liz Peck
Editor
Ken Butcher
Acknowledgement
Permission to reproduce extracts from BS EN 15193, BS EN 12464-2, BS EN
1838 and BS EN 12464-1 (draft) is granted by BSI. British Standards can be
obtained in PDF or hard copy formats from the BSI online shop:
www.bsigroup.com/Shop, or by contacting BSI Customer Services for
hardcopies only: tel: +44 (0)20 8996 9001, e-mail: cservices@bsigroup.com.
90
Lighting Guide 5: Lighting for education
Table 10.2 Recommended minimum controls provision
Type of space
Description
Recommended minimum controls
Owned space
A space such as a small room for
one or two people who control
the lighting, e.g. a cellular office
or tutorial room.
Shared space
A multi-occupied area, e.g.
classroom, common room, an
open-plan office or craft area.
Temporarily owned
space
A space where people are
expected to operate the lighting
controls while they are there,
e.g. a lecture or meeting room.
Occasionally visited
space
A space where people generally
stay for a relatively short period
of time when they visit the space,
e.g. a storeroom or toilet.
A space where individual users
require lighting but are not
expected to operate the lighting
controls, e.g. a corridor or atrium.
Manual switch by the door with
absence* override. Separate circuit
for daylight dimming, or switching,
of luminaires close to the window in
daylight spaces.
Manual switch by the door with
absence* override. Separate circuits
for daylight dimming or switching of
luminaires in appropriate zones
according to the amount of daylit
for daylight spaces.
Local manual control with absence*
override. Sensor(s) should be
suitably mounted to pick up the
movement of occupants and
speaker.
Manual on with absence* override.
Presence detection may be
acceptable provided sensors use no
more than 0.5 W.
Time switching, or manual on with
absence* override, or presence
provided individual sensors use no
more than 0.5 W.
Separate circuits for daylight
dimming or switching of luminaires
in appropriate zones according to
the amount of daylight for daylit
spaces.
Time switching, scene setting or
central switching by a responsible
person.
Un-owned space
Managed space
A space where lighting is under
the control of a responsible
person, e.g. a conference room,
theatre or sports hall.
Separate circuits for daylight
dimming or switching of luminaires
in appropriate zones according to
the amount of daylight for daylit
spaces.
* Absence sensors should be circuited such that they switch themselves off and hence use zero
power when the lighting is off.
11
Glossary
The definitions and explanations given in this glossary are intended to help
readers to understand this Lighting Guide. They are based on BS EN 12665:
Light and lighting. Basic terms and criteria for specifying lighting(67), which should be
consulted if more precise definitions are needed.
adaptation
The process by which the state of the visual system is modified by previous and
present exposure to stimuli that may have various luminances, spectral
distributions and angular subtenses.
adjoining spaces
Foyers, ante-rooms, lobbies and corridors immediately adjoining teaching
spaces listed in this Lighting Guide.
chromaticity
The property of a colour stimulus defined by its chromaticity coordinates, or by
its dominant or complementary wavelength and purity taken together.
Glossary
91
colour appearance (see also colour temperature)
A term used of a light source. Objectively the colour of a truly white surface
illuminated by the source. Subjectively, the degree of warmth associated with
the source colour. Lamps of low correlated colour temperature are usually
described as having a warm colour appearance and lamps of high correlated
colour temperature as having a cool appearance.
colour rendering
The effect of an illuminant on the colour appearance of objects by conscious or
subconscious comparison with their colour appearance under a reference
illuminant.
CIE 1974 general colour rendering index (Ra)
The mean of the CIE 1974 special colour rendering indices for a specified set of
eight test colour samples. In some cases R8 or R14 references are quoted
indicating use of the original 8 reference colour or a wider range of 14 reference
samples.
colour temperature (Tc )
The temperature of a Planckian radiator whose radiation has the same
chromaticity as that of a given stimulus (unit: K).
correlated colour temperature (Tcp )
The temperature of the Planckian radiator whose perceived colour most closely
resembles that of a given stimulus at the same brightness and under specified
viewing conditions (unit: K).
committee rooms
Rooms used for meetings capable of seating up to roughly 30 persons.
contrast
In the perceptual sense: assessment of the difference in appearance of two or
more parts of a field seen simultaneously or successively (hence brightness
contrast, lightness contrast, colour contrast, simultaneous contrast, successive
contrast etc.)
contrast rendering factor
The ratio of the contrast of a task under a given lighting installation to its
contrast under reference lighting conditions.
cut-off
The technique used for concealing lamps and surfaces of high luminance from
direct view in order to reduce glare.
cut-off angle (of a luminaire)
The angle, measured up from nadir, between the vertical axis and the first line
of sight at which the lamps and the surfaces of high luminance are not visible.
cylindrical illuminance (at a point, for a direction) (Ez )
The total luminous flux falling on the curved surface of a very small cylinder
located at the specified point, divided by the curved surface area of the cylinder.
The axis of the cylinder is taken to be vertical unless stated otherwise (unit: lux).
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Lighting Guide 5: Lighting for education
It is defined by the formula:
Ez =
1
π
∫ 4 πs r L sin ε dΩ
where Ω is the solid angle of each elementary beam passing through the given
point, L is the luminance at that point and ε is the angle between the elementary
beam passing through the given point and the given direction (unless otherwise
stated, that direction is vertical).
daylight factor (D)
The ratio of the illuminance at a point on a given plane due to the light received
directly or indirectly from a sky of assumed or known luminance distribution,
to the illuminance on a horizontal plane due to an unobstructed hemisphere of
this sky, excluding the contribution of direct sunlight to both illuminances.
diffused lighting
Lighting by means of luminaires having a distribution of luminous intensity
such that the fraction of the emitted luminous flux directly reaching the
working plane, assumed to be unbounded, is 40–60%.
direct lighting
Lighting by means of luminaires having a distribution of luminous intensity
such that the fraction of the emitted luminous flux directly reaching the
working plane, assumed to be unbounded, is 90–100%.
directional lighting
Lighting in which the light on the working plane or on an object is incident
predominantly from a particular direction.
emergency lighting
Lighting provided for use when the supply to the normal lighting fails.
emergency escape lighting
That part of emergency lighting that provides illumination for visibility for
people leaving a location or attempting to terminate a potentially dangerous
process before doing so.
flicker
The impression of unsteadiness of visual sensation induced by a light stimulus
whose luminance or spectral distribution fluctuates with time.
fusion frequency
The frequency of alternation of stimuli above which flicker is not perceptible.
general lighting
Substantially uniform lighting of an area without provision for special local
requirements.
glare
The discomfort or impairment of vision experienced when parts of the visual
field (e.g. sky or lamps) are excessively bright in relation to the general
surroundings.
Glossary
93
glare, disability
Disability glare may be expressed in a number of different ways. If threshold
increment (TI) is used the following values of TI shall be used (see CIE 31(68)):
5%, 10%, 15%, 20%, 25%, 30%. If glare rating (GR) is used the following values of
GR shall be used (see CIE 112(69)): 10, 20, 30, 40, 45, 50, 55, 60, 70, 80, 90.
glare, discomfort
Discomfort glare may be expressed by means of a ‘psychometric scale’ derived
from psychophysical experiments. If it is expressed using the unified glare
rating the following values of UGR shall be used (see CIE 117(70)): 10, 13, 16, 19,
22, 25, 28.
illuminance (at a point of a surface) (E)
The quotient of the luminous flux dφ incident on an element of the surface
containing the point, by the area dA of that element (unit: lm·m–2).
illuminance, average (E)
The illuminance averaged (mean average) over the specified area (unit: lx).
illuminance, maximum (Emax )
The highest illuminance at any relevant point on the specified surface (unit: lx).
maintained illuminance (Em )
The value below which the average illuminance on the specified area should not
fall (unit: lx). It is the average illuminance at the time maintenance should be
carried out.
illuminance, minimum (Emin )
The lowest illuminance at any relevant point on the specified surface (unit: lx).
illuminance, initial (Ei )
The average illuminance on the specified surface when the installation is new
(unit: lx).
illuminance uniformity
In this Lighting Guide this is taken as the ratio of minimum illuminance
(luminance) to average illuminance (luminance) on (of) a surface.
immediate surrounding area
A band with a width of at least 0.5 m surrounding the task area within the field
of vision.
indirect lighting
Lighting by means of luminaires having a distribution of luminous intensity
such that the fraction of the emitted luminous flux directly reaching the
working plane, assumed to be unbounded, is 0–10% intensity.
installed loading
The installed power of the lighting installation per unit area (for interior and
exterior areas) or per unit length (for road lighting) (unit: W·m–2 for areas;
kW·km–1 for road lighting).
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Lighting Guide 5: Lighting for education
keystone effect
The distortion of an image caused by projection onto a surface not at right
angles to the projector beam. It commonly occurs when a projector is tilted
upwards to throw an image on a vertical screen, causing the top of the image to
become wider than the bottom and can be easily corrected on most modern
projectors.
lamp lumen maintenance factor
The ratio of the luminous flux of a lamp at a given time in its life to the initial
luminous flux.
lamp survival factor
The fraction of the total number of lamps that continue to operate at a given
time under defined conditions and switching frequency.
large conference rooms
Rooms used mainly for conferences and meetings at which people may address
the audience from almost any point in the room. Such rooms will usually have
a seating capacity of more than 60.
lecture rooms
Rooms used mainly for the delivery of formal lectures, with basically flat floors
and fixed seating. This category includes rooms with a raised step or podium for
the lecturer, and rooms with one or two raised steps towards the rear of the seating.
lecture theatres
Rooms used for the delivery of formal lectures with raked floors and/or
balconies or galleries and with fixed seating.
lighting energy numeric indicator (LENI)
A numeric indicator of the total annual lighting energy required in the building
(unit: kW·h.m–2 per annum).
light output ratio (of a luminaire)
The ratio of the total flux of the luminaire, measured under specified practical
conditions with its own lamps and equipment, to the sum of the individual
luminous fluxes of the same lamps when operated outside the luminaire with
the same equipment, under specified conditions.
local lighting
Lighting for a specific visual task, additional to and controlled separately from
the general lighting.
localised lighting
Lighting designed to illuminate an area with a higher illuminance at certain
specified positions, for instance those at which work is carried out.
luminance (L)
Luminous flux per unit solid angle transmitted by an elementary beam passing
through a given point and propagating in a given direction, divided by the area
of a section of that beam normal to the direction of the beam and containing the
given point (unit: cd·m–2).
Glossary
95
luminaire lighting fitting (deprecated)
Apparatus that distributes, filters or transforms the light transmitted from one
or more lamps and which includes (except the lamps themselves) all the parts
necessary for fixing and protecting the lamps and, where necessary, circuit
auxiliaries together with the means for connecting them to the electrical supply.
luminaire maintenance factor
The ratio of the light output ratio of a luminaire at a given time to the initial
light output ratio.
mounting height
The vertical distance between the luminaire and the ground or floor, or between
the luminaire and a defined task plane (working plane).
multi-purpose rooms
Rooms used for a wide variety of purposes, such as school halls, assembly rooms,
and function rooms.
reflectance (ρ)
The ratio of the reflected radiant or luminous flux to the incident flux in the
given conditions.
room index
An index related to the dimensions of a room, and used when calculating the
utilisation factor and other characteristics of a lighting installation:
L×W
K = —————–
Hm (L + W)
where K is the room index, L is the length of the room, W is the width of the
room and Hm is the height of the luminaires above the floor or other relevant
horizontal plane. Consistent units must be used for the dimensions.
rooms for practical work
Rooms used regularly for class teaching purposes, without large permanent
pieces of apparatus set up. Such rooms will usually have a seating capacity of less
than 60. This category will include many teaching laboratories.
semi-direct lighting
Lighting by means of luminaires having a distribution of luminous intensity
such that the fraction of the emitted luminous flux directly reaching the
working plane, assumed to be unbounded, is 60–90%.
semi-indirect lighting
Lighting by means of luminaires having a distribution of luminous intensity
such that the fraction of the emitted luminous flux directly reaching the
working plane, assumed to be unbounded, is 10–40%.
spacing/height ratio
The ratio of spacing of the geometric centres of the luminaires to their height
above the reference plane.
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Lighting Guide 5: Lighting for education
stroboscopic effect
The apparent change of motion of an object when illuminated by periodically
varying light of appropriate frequency. This periodic motion is especially
noticeable in the light from discharge lamps with clear bulbs operating on
alternating current.
teaching rooms
Rooms used mainly for class teaching purposes, with flat floors and no fixed
furniture except possibly chalkboards and projection screens. Such rooms will
usually have a seating capacity of less than 60.
uniformity
See illuminance uniformity
veiling reflections
Specular reflections that appear on the object viewed and that partially or wholly
obscure the details by reducing contrast.
visual acuity
The capacity for seeing distinctly fine details that have very small angular
separation.
visual comfort
A subjective condition of visual well-being induced by the visual environment.
visual field
The area or extent of physical space visible to an eye at a given position and
direction of view.
visual performance
The performance of the visual system as measured for instance by the speed and
accuracy with which a visual task is performed.
References
1
The Construction (Design and Management) Regulations 2007 Statutory
Instruments No. 320 2007 (London: The Stationery Office) (2007) (available at
http://www.opsi.gov.uk/si/si200703) (accessed October 2010)
2
The Building Regulations 2000 Statutory Instruments 2000 No 2531 as amended by
The Building (Amendment) Regulations 2001 Statutory Instruments 2001 No. 3335
and The Building and Approved Inspectors (Amendment) Regulations 2006
Statutory Instruments 2006 No. 652) (London: The Stationery Office) (dates as
indicated) (London: The Stationery Office) (2007) (available at http://www.opsi.
gov.uk/stat.htm) (accessed October 2010)
3
The Building (Amendment) Regulations (Northern Ireland) 2006 Statutory Rules of
Northern Ireland No. 355 2006 (London: The Stationery Office) (2006) (available at
http://www.opsi.gov.uk/sr/sr200603) (accessed October 2010)
4
The Building (Scotland) Amendment Regulations 2009 Scottish Statutory
Instruments No. 119 2009 (London: The Stationery Office) (2009) (available at http://
www.opsi.gov.uk/legislation/scotland/s-200901) (accessed October 2010)
5
The Education (School Premises) Regulations 1996 Statutory Instruments 1996 No.
360 (London: Her Majesty’s Stationery Office) (1996) (available at
http://www.opsi.gov.uk/si/si199603.htm) (accessed October 2010)
6
Standards for School Premises (London: Department for Education and Schools)
(undated) (available at http://www.teachernet.gov.uk/docbank/index.cfm?id=3928)
(accessed October 2010)
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Lighting Guide 5: Lighting for education
stroboscopic effect
The apparent change of motion of an object when illuminated by periodically
varying light of appropriate frequency. This periodic motion is especially
noticeable in the light from discharge lamps with clear bulbs operating on
alternating current.
teaching rooms
Rooms used mainly for class teaching purposes, with flat floors and no fixed
furniture except possibly chalkboards and projection screens. Such rooms will
usually have a seating capacity of less than 60.
uniformity
See illuminance uniformity
veiling reflections
Specular reflections that appear on the object viewed and that partially or wholly
obscure the details by reducing contrast.
visual acuity
The capacity for seeing distinctly fine details that have very small angular
separation.
visual comfort
A subjective condition of visual well-being induced by the visual environment.
visual field
The area or extent of physical space visible to an eye at a given position and
direction of view.
visual performance
The performance of the visual system as measured for instance by the speed and
accuracy with which a visual task is performed.
References
1
The Construction (Design and Management) Regulations 2007 Statutory
Instruments No. 320 2007 (London: The Stationery Office) (2007) (available at
http://www.opsi.gov.uk/si/si200703) (accessed October 2010)
2
The Building Regulations 2000 Statutory Instruments 2000 No 2531 as amended by
The Building (Amendment) Regulations 2001 Statutory Instruments 2001 No. 3335
and The Building and Approved Inspectors (Amendment) Regulations 2006
Statutory Instruments 2006 No. 652) (London: The Stationery Office) (dates as
indicated) (London: The Stationery Office) (2007) (available at http://www.opsi.
gov.uk/stat.htm) (accessed October 2010)
3
The Building (Amendment) Regulations (Northern Ireland) 2006 Statutory Rules of
Northern Ireland No. 355 2006 (London: The Stationery Office) (2006) (available at
http://www.opsi.gov.uk/sr/sr200603) (accessed October 2010)
4
The Building (Scotland) Amendment Regulations 2009 Scottish Statutory
Instruments No. 119 2009 (London: The Stationery Office) (2009) (available at http://
www.opsi.gov.uk/legislation/scotland/s-200901) (accessed October 2010)
5
The Education (School Premises) Regulations 1996 Statutory Instruments 1996 No.
360 (London: Her Majesty’s Stationery Office) (1996) (available at
http://www.opsi.gov.uk/si/si199603.htm) (accessed October 2010)
6
Standards for School Premises (London: Department for Education and Schools)
(undated) (available at http://www.teachernet.gov.uk/docbank/index.cfm?id=3928)
(accessed October 2010)
References
97
7
Registration of independent schools — information pack (London: Department for
Education) (2010) (available at http://www.dcsf.gov.uk/reg-independent-schools)
(accessed October 2010)
8
Code for Lighting (CD-ROM) (London: Society of Light and Lighting) (2009)
9
SLL Lighting Handbook (London: Society of Light and Lighting) (2009)
10 Boyce P R Human factors in lighting ch. 4 (Oxford: CRC) (2003)
11 Hawkes R J, Loe D L and Rowlands E A note towards the understanding of lighting
quality’ J. Illum. Eng. Soc. 8 111–120 (1979)
12 Loe D L, Mansfield K P and Rowlands E ‘Appearance of a lit environment and its
relevance in lighting design: Experimental study’ Light. Res. Technol. 26 119–133
(1994)
13 Loe D L, Mansfield K P and Rowlands E ‘A step in quantifying the appearance of a
lit scene’ Light. Res. Technol. 32 213–222 (2000)
14 Heschong L Daylighting in Schools: An Investigation into the Relationship between
Daylighting and Human Performance (Fair Oaks, CA: Heschong Mahone Group) (1999)
15 Daylighting and window design CIBSE Lighting Guide LG10 (London: Chartered
Institution of Building Services Engineers) (1999)
16 Loe D L ‘Quantifying lighting energy efficiency: a discussion document’ Light. Res.
Technol. 35 319–329 (2003)
17 Directive 2005/32/EC of the European Parliament and of the Council of 6 July 2005
establishing a framework for the setting of ecodesign requirements for energy-using
products and amending Council Directive 92/42/EEC and Directives 96/57/EC and
2000/55/EC of the European Parliament and of the Council Official J. of the European
Union L191 29–58 (22.07.2005) (available at http://eur-lex.europa.eu/LexUriServ/
LexUriServ.do?uri=CELEX:32005L0032:EN:HTML) (accessed October 2010)
18 Conservation of fuel and power in new buildings other than dwellings Building Regulations
2000 Approved Document L2A (London: The Stationery Office) (2006) (available at
http://www.planningportal.gov.uk/england/professionals/en/1115314231806.html)
(accessed August 2008)
19 Conservation of fuel and power in buildings other than dwellings The Building Regulations
(Northern Ireland) 2000: Technical booklet F2 (London: The Stationery Office)
(2006) (available at http://www.opsi.gov.uk/legislation/northernireland/ni-srni.htm)
(accessed October 2010)
20 The Scottish Building Standards — Technical Handbook: Non-Domestic (Edinburgh:
Scottish Building Standards Agency) (2008) (available at http://www.sbsa.gov.uk/
tech_handbooks/tbooks2008.htm) (accessed October 2010)
21 Directive 2002/91/EC of the European Parliament and of the Council of 16 December
2002 on the energy performance of buildings (‘The Energy Performance of Buildings
Directive’) Official J. of the European Communities L1 65–71 (4.1.2003) (Brussels:
Commission for the European Communities) (2003) (available at http://
ec.europa.eu/energy/demand/legislation/buildings_en.htm)
22 BS EN 15193: 2007: Energy performance of buildings. Energy requirements for lighting
(London: British Standards Institution) (2007)
23 BREEAM: the environmental assessment method for buildings around the world (website)
(Garston: BRE Global) (2009)
24 Conservation of fuel and power in buildings other than dwellings Building Regulations
2000 Approved Document L2 (London: The Stationery Office) (2002) (superseded;
see reference 18)
25 The Waste Electrical and Electronic Equipment Regulations 2006 Statutory
Instruments no. 3289 2006 (London: The Stationery Office) (2006) (available at
http://www.opsi.gov.uk/si/si200632) (accessed October 2010)
26 Hathaway W E ‘A study into the effects of types of light on children — a case of
daylight robbery’ Proc Conf. 101st Annual Convention of the American Psychological
Association, Canada, August 1993 (1993)
27 Mass J, Jayson J and Kleiber D ‘Quality of light is important, not just quantity’
American School and University 46(12) 31 (1974)
28 Küller R and Lindsten C ‘Health and behaviour of children in classrooms with and
without windows’ J. Environmental Psychology 12 305–317 (1992)
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29 Heschong L Daylighting in Schools: Reanalysis Report (Sacremento CA: California
Energy
Commission)
(2003)
(available
at
http://newbuildings.org/
daylighting-schools-reanalysis-report) (accessed October 2010)
30 Littlefair P Site layout planning for daylight and sunlight — a guide to good practice
(Garston: BRE) (1998)
31 09/30206726 DC: BS EN 12464-1: Light and lighting. Lighting of work places. Part 1.
Indoor work places (draft for public comment) (London: British Standards Institution)
(2009)
32 BS EN 12193: 2007: Light and lighting. Sports lighting (London: British Standards
Institution) (2008)
33 BS 8206-2: 2008: Lighting for buildings. Code of practice for daylighting (London: British
Standards Institution) (2008)
34 Littlefair P Site layout planning for daylight and sunlight: a guide to good practice
(Garston: BRE Press) (1991)
35 Tregenza P R ‘Modification of the split-flux formulae for mean daylight factor and
internal reflected component with large external obstructions’ Lighting Res. Technol.
21(3) 125–128 (1989)
36 Winterbottom M and Wilkins A ‘Lighting and discomfort in the classroom’ J.
Environ. Psychology 29(1) 63–75 (2009)
37 Passive solar schools — a design guide Department for Education Architects and
Building Division Building Bulletin 79 (London: Her Majesty’s Stationery Office)
(1994)
38 Visual environment for display screen use CIBSE Lighting Guide LG3 (London:
Chartered Institution of Building Services Engineering) (1996) (out of print)
39 Office lighting SLL Lighting Guide LG7 (London: Society of Light and Lighting)
(2005)
40 The Ecodesign for Energy-Using Products Regulations 2007 Statutory Instruments
2007 No. 2037 (London: The Stationery Office) (2007) (available at http://www.opsi.
gov.uk/si/si200720) (accessed October 2010)
41 Ramasoot T and Folios S A ‘Acceptability of screen reflections: lighting strategies for
improving quality of the visual environment in classrooms of the future’ Proc. conf.
PLEA Dublin 2008: Towards zero energy building, University College Dublin, October
22–24 2008 (2008)
42 Lighting CIBSE Commissioning Code L (London: Chartered Institution of Building
Services Engineers) (2003)
43 Daylighting and window design CIBSE Lighting Guide LG10 (London: Chartered
Institution of Building Services Engineers) (1999)
44 BS EN 12464-1: 2002: Light and lighting. Lighting of work places. Indoor work places
(London: British Standards Institution) (2002)
45 Guidelines for specification of LED lighting products (Society of Light and
Lighting/Institution of Lighting Engineers/Lighting Industry Federation/
International Association of Lighting Designers/Professional Lighting Designers
Association/Highway Electrical Suppliers & Designers Association) (2009) (available
at http://www.cibse.org/index.cfm?go=page.view&item=369) (accessed October
2010)
46 BS 5266-1: 2005: Emergency lighting. Code of practice for the emergency lighting of premises
(London: British Standards Institution) (2005)
47 BS EN ISO 9241-307: 2008: Ergonomics of human-system interaction. Analysis and
compliance test methods for electronic visual displays (London: British Standards
Institution) (2010)
48 ISO 2603: 1998: Booths for simultaneous interpretation — General characteristics and
equipment (Geneva, Switzerland: International Organization for Standardization)
(1998)
49 Sports lighting SLL Lighting Guide LG4 (London: Society of Light and Lighting)
(2006)
50 Fotios S and Ramasoot T ‘Developing a model to predict user acceptability of display
screen reflections’ Proc. Conf. Lux Europa, Istanbul, 9–11 September 2009 513–520
(2009)
References
99
51 Industry SLL Lighting Guide LG1 (on Code for Lighting (CD-ROM)) (London: Society
of Light and Lighting) (2009)
52 BS EN 12464-2: 2007: Lighting of work places. Outdoor work places (London: British
Standards Institution) (2007)
53 BS 5489-1: 2003 + A2: 2008: Code of practice for the design of road lighting. Lighting of
roads and public amenity areas (London: British Standards Institution) (2003/2008)
54 BS EN 13201-2: 2003: Road lighting. Performance requirements (London: British
Standards Institution) (2003)
55 BS EN 13201-3: 2003: Road lighting. Calculation of performance (London: British
Standards Institution) (2003)
56 The Regulatory Reform (Fire Safety) Order 2005 Statutory Instruments No. 1541
2005 (London: The Stationery Office) (available at http://www.opsi.gov.uk/si/
si200515)(accessed October 2010)
57 BS 5499-4: 2000: Safety signs, including fire safety signs. Code of practice for escape route
signing (London: British Standards Institution) (2000)
58 BS 5499-1: 2002: Graphical symbols and signs. Safety signs, including fire safety signs.
Specification for geometric shapes, colours and layout (London: British Standards
Institution) (2002)
59 09/30197377 DC: BS ISO 3864-1: Graphical symbols. Safety colours and safety signs. Part
1. Design principles for safety signs and safety markings (draft for public comment)
(London: British Standards Institution) (2009)
60 BS EN 1838: 1999, BS 5266-7: 1999: Lighting applications. Emergency lighting (London:
British Standards Institution) (1999)
61 BS EN 50172: 2004, BS 5266-8: 2004: Emergency escape lighting systems (London:
British Standards Institution) (2004)
62 BS EN 62034: 2006: Automatic test systems for battery powered emergency escape lighting
(London: British Standards Institution) (2007)
63 ISO 30061: 2007 (CIE S 020/E:2007): Emergency lighting (Geneva, Switzerland:
International Organization for Standardization) (1998)
64 BS 4533-102: Luminaires. Particular requirements (4 sections) (London: British
Standards Institution) (1990)
65 BS EN 60598-1: 2008: Luminaires. General requirements and tests (London: British
Standards Institution) (2009)
66 BS 7671: 2008: Requirements for electrical installations. IEE Wiring Regulations.
Seventeenth edition (London: British Standards Institution) (2008)
67 BS EN 12665: 2002: Light and lighting. Basic terms and criteria for specifying lighting
requirements (London: British Standards Institution) (2002)
68 Glare and uniformity in road lighting installations CIE 31 (Vienna, Austria: International
Commission on Illumination) (2002)
69 Glare evaluation system for use within outdoor sports and area lighting CIE 112 (Vienna,
Austria: International Commission on Illumination) (1994)
70 Discomfort glare in interior lighting CIE 117 (Vienna, Austria: International Commission
on Illumination) (1995)
Contents
1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
2
Components of lighting design . . . . . . . . . . . . . . . . .1
3
4
5
2.1
Objectives and constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
2.2
Lighting for visual function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
2.3
Lighting for visual amenity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
2.4
Lighting and architectural integration . . . . . . . . . . . . . . . . . . . . . . .4
2.5
Lighting and energy efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
2.6
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
2.7
Lighting costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
2.8
Lighting for health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Lighting options . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3.1
Natural lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3.2
Electric lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
3.3
Integrated daylighting and electric lighting . . . . . . . . . . . . . . . . . .17
3.4
Lightness of the interior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
3.5
Room surface reflectance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
3.6
Lighting the interior space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
3.7
Mean cylindrical illuminance . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
3.8
Modelling index and directional light . . . . . . . . . . . . . . . . . . . . . . .22
Lighting design guidance . . . . . . . . . . . . . . . . . . . . .22
4.1
Daylighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
4.2
Electric lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
4.3
Integrated daylight and electric lighting . . . . . . . . . . . . . . . . . . . .35
4.4
Aids to lighting design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Lighting for particular applications . . . . . . . . . . . . .37
5.1
Classification of teaching and conference spaces . . . . . . . . . . . . .37
5.2
General performance requirements for learning spaces . . . . . . . . .37
5.3
Lecture theatres and lecture rooms . . . . . . . . . . . . . . . . . . . . . . . .39
5.4
Teaching rooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
5.5
Large conference rooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
5.6
Committee and meeting rooms . . . . . . . . . . . . . . . . . . . . . . . . . . .52
5.7
Multi-purpose rooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
5.8
Adjoining spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
5.9
Waiting areas and lobbies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
5.10
Areas with display screen equipment . . . . . . . . . . . . . . . . . . . . . . .57
5.11
Laboratories, work shops and other practical learning spaces . . . .59
5.12
Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
5.13
Sports halls and gymnasia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
5.14
General purpose halls, and drama and dance studios . . . . . . . . . .62
5.15
Lighting for whiteboards and projection screens . . . . . . . . . . . . . .63
5.16
Lighting and visual aids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
5.17
Lighting for pupils with visual and hearing impairments . . . . . . . .65
5.18
Local task lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
6
5.19
Exterior lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
5.20
Emergency lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70
Checklist for lighting design . . . . . . . . . . . . . . . . . .77
6.1
Task/activity lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77
6.2
Lighting and energy efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . .79
7
Lighting maintenance . . . . . . . . . . . . . . . . . . . . . . . .80
8
Management of lecture and conference spaces . . .81
9
10
11
8.1
Visual clutter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81
8.2
Lecture attendants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81
8.3
Communication between lecturer and projectionist or projector . .82
8.4
Projection rooms and booths . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82
8.5
Preparation and equipment rooms . . . . . . . . . . . . . . . . . . . . . . . .82
8.6
Problems for visiting lecturers . . . . . . . . . . . . . . . . . . . . . . . . . . . .82
8.7
Lectures involving demonstrations . . . . . . . . . . . . . . . . . . . . . . . . .83
Lighting costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83
9.1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83
9.2
Emergency lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83
Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83
10.1
Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83
10.2
Control gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83
10.3
Lighting controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
10.4
Disposal of used lighting equipment . . . . . . . . . . . . . . . . . . . . . . .88
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98
Appendix A1: luminance limits and . . . . . . . . . . .100
display screen equipment
Introduction
1
1
Introduction
Learning, whether by discussion, interaction, practical application or formal
lecture, requires sufficient light to enable the pupils to see the visible
information presented around them. Whether in a primary school classroom or
a professional lecture theatre, whether for young or old, the quality of light we
choose to provide in the learning environment will directly affect our learning
experience and indeed our motivation to learn. If we cannot see clearly what is
written on the board, identify true colours, or read the facial expression and
body language of our teacher, then our learning and our experience will fail to
meet our needs. Above all aspects we can create in a learning space, that of the
lighting affects us most. Harsh light creating aggressive facial modelling, or
excessive daylight urging the teacher to draw the blinds and use electric light,
impact upon us and our environment. More so now than at any other time in the
history of lighting, we have to create stimulating and sustainable learning
environments.
The function of this Lighting Guide is to offer advice on the lighting of
educational spaces (specifically those not covered elsewhere), lecture theatres,
teaching rooms, conference rooms and multi-purpose rooms, and on the visual
problems that may arise. It is therefore necessary to discuss other matters than
simply the lighting equipment and its positioning. The decoration and finishes
of such rooms, the sightlines, the positioning of lighting controls and access
doors all need to be taken into account. The lighting is a vital element in such
rooms and requirements of lighting should be taken into account from the first
stages of the planning.
This point cannot be too strongly emphasised. Light is so important to
the functioning of all the premises covered by this Lighting Guide that it must
be considered from the very outset of the planning process. As lighting design
is such a vital part of the success and performance of both space and student the
designer of such spaces must be able to demonstrate clearly their competence in
lighting design for such spaces either by qualification or experience.
By ‘lighting’ it is important to stress that we mean both natural and
electric lighting; experience shows that whilst much thought is given to natural
lighting, i.e. window design, planning for electric lighting is often left until far
too late in the design process. Equally, developments driving sustainable
buildings have often led to natural lighting schemes that introduce other
problems such as overheating, glare and so on.
That said, natural lighting should be used as far as possible as the primary
light source in all teaching environments. There will be exceptions where
daylight needs to be excluded but these are few and in most cases simple and
functional control of daylight ingress when required will suffice.
2
Components
of lighting
design
2.1
Objectives and
constraints
Lighting design can have many different objectives. Ideally, these objectives are
determined by the client and the lighting designer in collaboration and cover
both outcomes and costs (Figure 2.1). The most common objective for a lighting
installation is to allow the users of a space to carry out their work quickly and
accurately, without discomfort. However, this is a rather limited view of what a
lighting installation can achieve. For educational spaces, the objective of
lighting is to facilitate the learning of students by passing on information from
the teacher or lecturer and via other media. For these tasks the requirements of
the lecturer will often be different from those of the pupils. In lecture theatres
the task of presenting may require dimmed lighting to enable clear images on
the screen, but the need to take notes may require increased lighting levels,
particularly for those with impaired sight. Educational sport facilities are lit at
night to encourage their use in the wider community, but in doing so they may
impinge upon the residential areas surrounding the school. Most lighting
installations have to serve multiple functions. When designing lighting it is
always desirable at the outset of the project to identify all the functions that the
lighting is expected to fulfil.
Introduction
1
1
Introduction
Learning, whether by discussion, interaction, practical application or formal
lecture, requires sufficient light to enable the pupils to see the visible
information presented around them. Whether in a primary school classroom or
a professional lecture theatre, whether for young or old, the quality of light we
choose to provide in the learning environment will directly affect our learning
experience and indeed our motivation to learn. If we cannot see clearly what is
written on the board, identify true colours, or read the facial expression and
body language of our teacher, then our learning and our experience will fail to
meet our needs. Above all aspects we can create in a learning space, that of the
lighting affects us most. Harsh light creating aggressive facial modelling, or
excessive daylight urging the teacher to draw the blinds and use electric light,
impact upon us and our environment. More so now than at any other time in the
history of lighting, we have to create stimulating and sustainable learning
environments.
The function of this Lighting Guide is to offer advice on the lighting of
educational spaces (specifically those not covered elsewhere), lecture theatres,
teaching rooms, conference rooms and multi-purpose rooms, and on the visual
problems that may arise. It is therefore necessary to discuss other matters than
simply the lighting equipment and its positioning. The decoration and finishes
of such rooms, the sightlines, the positioning of lighting controls and access
doors all need to be taken into account. The lighting is a vital element in such
rooms and requirements of lighting should be taken into account from the first
stages of the planning.
This point cannot be too strongly emphasised. Light is so important to
the functioning of all the premises covered by this Lighting Guide that it must
be considered from the very outset of the planning process. As lighting design
is such a vital part of the success and performance of both space and student the
designer of such spaces must be able to demonstrate clearly their competence in
lighting design for such spaces either by qualification or experience.
By ‘lighting’ it is important to stress that we mean both natural and
electric lighting; experience shows that whilst much thought is given to natural
lighting, i.e. window design, planning for electric lighting is often left until far
too late in the design process. Equally, developments driving sustainable
buildings have often led to natural lighting schemes that introduce other
problems such as overheating, glare and so on.
That said, natural lighting should be used as far as possible as the primary
light source in all teaching environments. There will be exceptions where
daylight needs to be excluded but these are few and in most cases simple and
functional control of daylight ingress when required will suffice.
2
Components
of lighting
design
2.1
Objectives and
constraints
Lighting design can have many different objectives. Ideally, these objectives are
determined by the client and the lighting designer in collaboration and cover
both outcomes and costs (Figure 2.1). The most common objective for a lighting
installation is to allow the users of a space to carry out their work quickly and
accurately, without discomfort. However, this is a rather limited view of what a
lighting installation can achieve. For educational spaces, the objective of
lighting is to facilitate the learning of students by passing on information from
the teacher or lecturer and via other media. For these tasks the requirements of
the lecturer will often be different from those of the pupils. In lecture theatres
the task of presenting may require dimmed lighting to enable clear images on
the screen, but the need to take notes may require increased lighting levels,
particularly for those with impaired sight. Educational sport facilities are lit at
night to encourage their use in the wider community, but in doing so they may
impinge upon the residential areas surrounding the school. Most lighting
installations have to serve multiple functions. When designing lighting it is
always desirable at the outset of the project to identify all the functions that the
lighting is expected to fulfil.
2
Fig. 2.1
Lighting Guide 5: Lighting for education
Objectives, outcomes and
costs
Visual
function
Architectural
integration
Visual
amenity
Lighting
design
Costs
(capital and
operating)
Energy
efficiency
Installation
maintenance
As for constraints, an important aspect of lighting design is the need to
minimise the amount of electricity consumed, for both financial and
environmental reasons. It is also necessary to consider the sustainability of the
lighting equipment. This means using materials that can be easily replaced and
considering to what extent the equipment can be recycled at the end of its life.
The financial costs, particularly the capital cost, are always an important
constraint. No one wants to pay more for something than is absolutely necessary
so the lighting designer needs to be able to justify the proposal in terms of value
for money.
2.1.1
A holistic strategy
for lighting
A holistic strategy for lighting design is necessary because without it important
benefits will be lost, and money and human resources will be wasted. The
starting point is an in-depth conversation with the client and other members of
the design team to formulate a design brief. This from a ‘whole building’ design
perspective needs to branch out from natural and electric lighting to include the
effects on thermal loading, ventilation and acoustics.
At such a discussion, it will be necessary to address such fundamental
questions as: what do you want to see and what do you not want to see, what is
the function of the space, what is the proposed architectural style, and what is
the budget?
More formally, six distinct aspects of lighting need to be considered.
They are: legal requirements, visual function, visual amenity, architectural
integration, energy efficiency and sustainability
All these aspects will contribute to the success of a design, but they may
not all carry equal weight depending on the particular application and situation.
Also there is no particular order in which they should be considered. The
important issue is that all the elements are considered at the inception of the
project and again at each key stage of the design process, perhaps more than
once, for a satisfactory solution to emerge.
2.1.2
Legal requirements
There are a number of legal requirements that apply to all lighting installations.
Some are general, e.g. the Construction (Design and Management)
Regulations(1). Some are specific about the type and form the lighting that
should be provided, e.g. emergency lighting in buildings (see chapter 9). Others
influence lighting design by the limits they place on the type or amount of
equipment that can be used, e.g. Building Regulations(2–4). Details of the
requirements of the Construction (Design and Management) Regulations can be
obtained from Health and Safety Executive publications. It is essential that the
designer and the client are aware of the relevant legal requirements.
The Education (School Premises) Regulations(5) specify minimum
standards for the premises of all maintained schools in England and Wales. The
Components of lighting design
3
publication Standards for School Premises(6), provides guidance on the School
Premises Regulations.
Some of the provisions of the School Premises Regulations also apply to
independent schools. Guidance on legislation applying to independent schools
is included in the Department for Education’s Registration of Independent Schools
Information pack(7). As the UK devolves central government control to individual
countries there may be other Regulations under similar titles to be considered.
Schools are covered by the Building Regulations(2–4). In some cases, DfES
Building Bulletins are referred to in Building Regulations Approved
Documents. Except in these cases, or as otherwise stated, these publications are
non-statutory.
2.2
Lighting for
visual function
This aspect is related to the lighting required for doing tasks without discomfort. Recommended illuminance for different tasks is given in the Code for
Lighting(8) and the SLL Handbook(9), as well as in chapters 5 and 6 of this
Lighting Guide. These values apply to the task area and do not necessarily need
to apply to the whole working plane. Establishing which values apply to which
task needs to be done with knowledge of how the space will function both now
and in the future, where this information is available. Equally it is a decision
that needs to be made with cognisance of all other aspects of the lighting and
building design.
The traditional way of lighting a work place has been a regular array of
luminaires. For this approach, minimum task illuminance uniformity
(minimum/average task illuminance ≥ 0.7) is recommended. This approach has
the benefit that the tasks can be carried out on the horizontal plane anywhere in
the work place but does tend to over-light areas not used for the primary task
that happen to fall within an imaginary work plane. It should be noted that a
more visually appealing and stimulating space can be created with additional
energy saving benefits if the lighting is focused where it is needed. See sections
2.3 and 2.5.
In some cases the task will have a colour recognition element. In such
cases it will be necessary to use lamps with a high colour rendering index (CRI).
For such tasks it will is appropriate to use lamps with a CRI ≥ 80 but for tasks
with a requirement for very good colour discrimination, lamps with a CRI ≥ 90
will be necessary.
The human visual system can adapt to a wide range of luminance but it
can cope with only a limited luminance range at any single adaptation state.
When this range is exceeded, glare will occur. If a field of view contains bright
elements that cause glare it is likely that they will affect performance, or at least
cause stress and fatigue which, in turn, will cause problems. To avoid this will
mean using luminaires and windows that have limited luminance within the
normal fields of view relative to the adaptation level. Glare limits for different
tasks are given in the Code for Lighting(8) and the SLL Handbook(9), as well as in
chapters 5 and 6 of this Lighting Guide.
2.3
Lighting for
visual amenity
There is no doubt that lighting can add visual amenity to a space that can give
pleasure to the occupants but whether this provides a more tangible
performance benefit is uncertain(10). Studies have shown that people respond to
the lit appearance of a room on two independent dimensions, visual lightness
and visual interest(11–13). Visual lightness describes the overall lightness of the
space, which is related to the average luminance of vertical surfaces. Visual
interest refers to the non-uniformity of the illumination pattern or the degree of
‘light and shade’. People prefer some modulation in the light pattern rather than
an even pattern of illumination, the magnitude of the modulation depending on
the application. There is some evidence that visual lightness and visual interest
are inversely correlated (Figure 2.2).
4
Map showing the possible
locations of three
application areas on a
schematic diagram linking
subjective impressions of
visual interest and visual
lightness
High
Visual interest (degree of
light non-uniformity)
Fig. 2.2
Lighting Guide 5: Lighting for education
Leisure
Education and
commercial
Industrial
Low
Low
High
Visual lightness (brightness)
Although variation in the light pattern is desirable, it has to be seen as
meaningful in terms of the application and the architecture. To provide random
patches of light in an uncoordinated way for no reason other than to provide
light variation would be a poor design solution. Acceptable examples could be
highlighting displays within a retail outlet, or a floral display in a hotel lobby.
There remains one further area of visual amenity that needs to be
considered and that is the colour appearance of the light. A light source with a
correlated colour temperature (CCT) ≤ 3000 K will appear warm, and if it has a
CCT ≥ 5300 K it will appear cold (see the SLL Handbook(9), section 1.4.3). Where
on this scale from warm to cool the colour appearance should fall will depend on
the nature of and finishes in the space. In domestic situations a warm colour
appearance will be required but in educational interiors a CCT of around 4000 K
is appropriate as it blends reasonably well with daylight. The designer should be
wary of the names applied to light sources as these can be misleading and differ
between manufacturers. The best way to choose colour appearance is through
practical trials.
There is still much to learn about design for visual amenity but it would
be negligent to ignore it. The best way to develop an understanding of visual
amenity is though personal observations and trial installations.
2.4
Lighting and
architectural
integration
All elements of a lighting installation form part of the architecture or the
interior design of a building. Understanding the space will be important when
deciding what sort of lighting is to be employed. The dimensions, finishes,
texture, colour, materials and the atmosphere to be created are among some of
the attributes that should be considered.
The most appropriate place to start is with the daylighting, given the
positive impact that well designed sunlit and daylit learning spaces have on the
ability for individuals to learn and develop(14). The windows and roof lights are
a fundamental element of the fabric of the building. This means considering the
amount and pattern of daylight required for the particular application, and
hence the size and positions of windows and rooflights. But windows cannot be
designed on the basis of the daylighting alone and other visual, thermal, acoustic
and privacy issues need to be addressed. There is a clear hierarchy for successful
environmental design:
(1)
Daylight design.
(2)
Prevention of summertime overheating.
(3)
Design of ventilation.
(4)
Acoustic design.
Components of lighting design
5
This is an iterative process but daylight design must come first as it
affects the form of the building. More information on daylighting design can be
obtained from the SLL Lighting Guide LG10: Daylighting and window design(15),
section 6.3 of the SLL Handbook(9) and section 3.1 of this Lighting Guide.
Simple design tools for classroom design are also available, such as ClassCool
and ClassVent produced by the Department for Children, Schools and Families
and available from the teachernet website (www.teachernet.gov.uk/iaq).
Once the daylighting has been determined then the electric lighting can
be planned. To integrate electric lighting with the architecture means
considering not only its operation with respect to the daylighting, but the
appearance of the luminaires and controls and the way they are incorporated
into the fabric of the building, as well as the lighting effect produced. Such
integration may include other building services and could be incorporated into
acoustic raft type lighting systems where appropriate.
Just as the light pattern needs to be meaningful with respect to the
building use, the lighting scheme needs to be meaningful with respect to the
architecture and colour finishes. Profound effects are claimed in learning spaces
from colour choice, see section 3.5.
2.5
Lighting and
energy
efficiency
It is the responsibility of the lighting profession to use energy as efficiently as
possible but at the same time to provide lit environments that enable people to
operate effectively with comfort. The current estimate for the UK is that
approximately 19% of the electricity generated is consumed by lighting. This
amounts to around 64 TW·h/annum. In schools the lighting is responsible
currently for one third of carbon emissions in primary schools, and nearly half
in secondary premises, the figure rising significantly for educational
establishments operating outside of normal daylight hours.
Energy use involves two components: the power demand of the
equipment and its hours of use. The lighting industry has worked hard to
develop equipment that has reduced the demand for electricity for lighting by
producing more efficient light sources and their related control circuits as well
as more efficient luminaires. Then there are design options to be considered,
such as the use of task/ambient lighting rather than a blanket provision of light
by a regular array of ceiling mounted luminaires. The savings for the
task/ambient approach have been estimated to be up to 50 percent(16).
Good energy efficient lighting design is not just about equipment; it is
also about the use of lighting. Far too often whilst the initial building design
seeks to deliver well daylit spaces, as the design progresses other factors such as
thermal design, acoustics, cost and ‘buildability’ dominate the solution and
reduce the available access to sunlight and daylight. Given the positive impact
sunlight and daylight have on the learning environment, and its ability to allow
the electric lighting to be switched off, designing for daylight needs to be
promoted more vigorously throughout the design process. There are also many
examples where lighting is left on when it is not required. This may be because
there is adequate lighting through daylighting or because people are not present
and therefore the lighting is unnecessary. This aspect of lighting design needs a
dramatic change in attitude to improve the energy efficiency of all lighting
installations. This requires changes to how the lighting is controlled, both
manually and automatically, as well as how lighting is provided in terms of the
distribution of light, particularly with respect to the daylighting.
It is also necessary to use equipment that is sustainable. This means that
wherever possible the materials used should be from renewable sources,
provided by ethical and environmentally sustainable methods, and that at the
end of its life the redundant equipment is capable of being disposed of safely
with most of the base materials being recycled. Equipment should also be ‘ecodesigned’, allowing for designs that make recycling simple and energy efficient,
that minimise material waste and that minimise maintenance and lamp
requirements through life. Over the next decade legislation such as the Energy-
6
Lighting Guide 5: Lighting for education
using Products Directive(17) will drive lamp, gear and luminaire choice and the
designer should specify in advance lighting that will meet or exceed
requirements.
The most efficient lighting solutions should be procured.
Lamp–luminaire combinations are now available that easily exceed the
minimum targets required by the Building Regulations(2–4), even considering
the 2010 levels. Designers should recognise the need to use the most efficient
lighting solutions that exceed current energy efficiency targets in documents
such as Approved Document L(18) (for England and Wales), Part F(19) (for
Northern Ireland) and Part J(20) (for Scotland) and also the Energy Performance
in Buildings Directive(21).
Where the usage profile of the building is not known, suitable minimum
targets for luminaire efficacy are given in Table 2.1.
Table 2.1 Energy compliance targets where building usage profiles are not available
Energy efficiency
grade
Luminaire efficacy for stated type of space*
(luminaire lumens per circuit watt)
Teaching spaces, office,
industrial, storage
Other spaces
Display lighting
Pass
55
55
22
Good
55
55
22
Excellent
55
55
22
* Averaged for all these spaces in the building
Note: ‘Good’ = a minimum of 60% of the installed lighting load must be under daylight control;
‘Excellent’ = a minimum of 60% of the installed lighting load must be under daylight and
absence control
Where a new educational building is being provided to replace an existing
building, or buildings, it is not acceptable to use the above method except as a
rough guide. Measurement of the existing building should be taken in order to
provide data for the likely use of the new building and this should be used for
the calculation of the lighting energy numeric indicator (LENI) as a measure of
the new designs energy efficiency.
The above targets are based on the Building Regulations and include
targets that recognise the important energy savings available from sensible
automatic control of lighting, but they do not include an overall measure of the
efficiency of the luminaires in all applications, so as the preferred method the
designer should utilise the Energy Performance in Buildings Directive(21)
(EPBD) as a target assessment.
As the targets and methodology in BS EN 15193(22) are subject to change
the designer should consider the British Standard. Generally, as schools should
utilise good daylighting, constant illuminance controls make sense and should
be combined with automatic absence detection to most spaces. A sensible ‘pass’
grade for the LENI in educational buildings would be taken from Table 2.1 in
Annex 5 of BS EN 15193 (see Table 2.2) but the designer should try and improve
on these levels (see Tables 2.3 and 2.4).
Whilst it is possible to achieve a LENI of near 10 kW·h/m2 per annum in
classrooms, the same may not be so easy across a whole building. Similarly, it
may be easy to simply achieve 55 luminaire lumens per circuit watt, either with
current or emerging light sources, gear and optical design (based on proposed
targets for England and Wales of 55 luminaire lumens per circuit watt from
October 2010) but this ignores significant savings in use. Hence, the designer
must consider the careful use of controls, utilising daylight, absence and
constant illuminance measures to limit the use of lighting as well as aspiring to
use the best available luminaire designs.
Quality
class
*
**
***
Parasitic
Parasitic
Pn
energy, Pem energy, Ppc (W/m2)
(kW·h/m2 (kW·h/m2
per year) per year)
1
1
1
5
5
5
15
20
25
tD
(h)
1800
1800
1800
tN
(h)
200
200
200
FC
FO
No constant Constant
illuminance illuminance
1
1
1
0.9
0.9
0.9
Manual
control
FD
Auto
control
1
1
1
0.9
0.9
0.9
Manual
control
LENI (limiting value)
Auto
control
1
1
1
0.8
0.8
0.8
No constant
illuminance
Constant
illuminance
Manual
control
Auto
control
Manual
control
Auto
control
34.9
44.9
54.9
27.0
34.4
41.8
31.9
40.9
49.9
24.8
31.4
38.1
Components of lighting design
Table 2.2 ‘Pass’ targets for lighting energy numeric indicator (LENI) for educational buildings (extract from BS EN 15193(22), Annex F, Table F.1, reproduced by permission of the British Standards
Institution)
Table 2.3 ‘Good’ targets for lighting energy numeric indicator (LENI) for educational buildings
Quality
class
*
**
***
Parasitic
Parasitic
Pn
energy, Pem energy, Ppc (W/m2)
(kW·h/m2 (kW·h/m2
per year) per year)
1
1
1
5
5
5
10.5
14
17.5
tD
(h)
1800
1800
1800
tN
(h)
200
200
200
FC
FO
No constant Constant
illuminance illuminance
1
1
1
0.9
0.9
0.9
Manual
control
FD
Auto
control
1
1
1
0.9
0.9
0.9
Manual
control
LENI (limiting value)
Auto
control
1
1
1
0.8
0.8
0.8
No constant
illuminance
Constant
illuminance
Manual
control
Auto
control
Manual
control
Auto
control
25.9
32.9
39.9
20.4
25.5
30.7
23.8
30.1
36.4
18.8
23.5
28.1
Table 2.4 ‘Excellent’ targets for lighting energy numeric indicator (LENI) for educational buildings
Quality
class
*
**
***
Parasitic
Parasitic
Pn
energy, Pem energy, Ppc (W/m2)
(kW·h/m2 (kW·h/m2
per year) per year)
1
1
1
5
5
5
6
8
10
tD
(h)
1800
1800
1800
tN
(h)
200
200
200
FC
FO
No constant Constant
illuminance illuminance
1
1
1
0.9
0.9
0.9
Manual
control
1
1
1
FD
Auto
control
0.9
0.9
0.9
Manual
control
1
1
1
LENI (limiting value)
Auto
control
0.8
0.8
0.8
No constant
illuminance
Constant
illuminance
Manual
control
Auto
control
Manual
control
Auto
control
16.9
20.9
24.9
13.7
16.7
19.6
15.7
19.3
22.9
12.8
15.5
18.1
7
8
Lighting Guide 5: Lighting for education
Table 2.5 Lighting design criteria class for use with Tables 2.2 to 2.4 (reproduced from BS
EN 15193(22) by permission of the British Standards Institution)
Criterion
Lighting design
criteria class
*
**
***
Maintained illuminance on horizontal visual tasks (Em horizontal)
✓
✓
✓
Appropriate control of discomfort glare (UGR)
✓
✓
✓
Avoidance of flicker and stroboscopic effects
✓
✓
✓
Appropriate control of veiling reflections and reflected glare
✓
✓
Improved colour rendering
✓
✓
Avoidance of harsh shadows or too diffuse light in order to provide
good modelling
✓
✓
Proper luminance distribution in the room (Evertical)
✓
✓
Special attention of visual communication in
lighting faces (modelling index, Ecylindrical)
✓
Special attention to health issues (see note)
✓ Must comply with required values from Table 5.3 in BS EN 12464-1
✓ Must conform to verbally described requirements from BS EN 12464-1
Note: health issues may even require higher illuminances and therefore higher W/m2
✓
To achieve such an improvement, coupled with much higher requirements for daylight contribution, the designer will need to consider
automatically controlled and/or dimmable luminaires for at least 60% of the
building space.
The targets set by the Building Regulations are considered to be
minimum standards of performance but these measures do not reflect the actual
use of the space and in some way makes no sense as it allows for efficient lamps
and gear in an inefficient luminaire. The designer should use practical control
along with efficient luminaires to provide best efficacy.
2.6
Maintenance
It must be recognised that both daylight and electric light within a building will
depreciate with time. To minimise the effect of this a maintenance programme
will need to be designed and implemented. The maintenance programme will
also affect the lighting design and the designer will need to state the maintenance programme on which the design has been based, otherwise there could
be problems when a client is comparing different design proposals. It is essential
for the client to be provided with a maintenance schedule so that they know
what will need to be done. Section 7 of this Lighting Guide discusses the various
factors that need to be considered when developing a maintenance program.
2.7
Lighting costs
Cost is always a major concern for any project and it is of course important to
consider these before any work is undertaken. Both the capital cost and the
running or operational costs must be considered at the outset. If the two cost
elements are not considered together in terms of life cycle costing, then a
solution which has a low capital cost but a high operational cost could prove
significantly more costly overall than an installation with a more expensive
capital cost but a low operating cost. A conflict of interests may arise if the two
cost elements are paid for from different budgets or organisations. Here the
Components of lighting design
9
designer needs to present a balanced view of the options to enable the client(s)
to decide on the best approach.
The capital costs include the cost of the design process, the equipment
and the installation process, both physical and electrical. It should also include
the commissioning and testing of the installation and training for the building
occupier/owner. Allowance must also be made for any builders’ work that forms
part of the lighting installation and any other costs that are particular to the
lighting design need to be included. It is important that the capital cost is agreed
at an early stage if a lot of time is not to be wasted. The capital cost should be
challenged if the client’s expectations seem to be unrealistic.
The operational costs include the cost of the electricity consumed, which
comprises items such as standing charges, maximum demand charges and
electricity unit costs. They will also include the cost of maintenance, which
includes cleaning and relamping throughout the life of the installation. In some
cases charges may have to be budgeted for the disposal of redundant equipment
although this may be borne by the supplier. Note that all electrical equipment
suppliers must be registered as part of the Waste Electrical and Electronic
Equipment Directive(25) (WEEE) and the designer should provide proof of this
for any electrical equipment supplied as part of their design.
The designer should consider the full and true life cycle costs, so called
‘cradle-to-grave’. This includes elements of the luminaires and other building
materials from the point their raw materials are sourced, to the point they are
recycled into reusable materials. Figure 2.3 shows the elements a design should
consider. These include:
Fig. 2.3
—
Materials: what material is used from the point it is dug out of
the ground to the point it is used in a product? For instance, the
creation of plastic from crude oil to the point they are moulded
into a diffuser whether their type and use makes recycling easy
in the future.
—
Ecology: the impact on sourcing raw materials and processing it
into a product on the environment, flora and fauna, plus the
impact of the product’s use on the environment.
—
Life cycle cost: the financial cost of the product from the point of
raw material to fully recycled, including any manufacture,
transport, use and recycling costs.
Considerations for
sustainable lighting design
Ecology
Materials
Lifecycle
cost
Transport
Sustainable
lighting
design
Health and
wellbeing
Passive
integration
Recycling
10
Lighting Guide 5: Lighting for education
—
Health and wellbeing: the impact of the lighting on both end
users and those close by who may inadvertently come into
contact with the scheme, for example those using a school sports
field and those residents nearby who may suffer light nuisance
from the pitch lighting.
—
Recycling: the impact of collecting and treating any waste created
by the lighting and luminaires, including the possibility that the
product may not be suited for complete recycling but may only
be down-cycled into other uses.
—
Passive integration: the impact of luminaires and the energy they
use on other services such as heating, cooling and ventilation of
a space. For instance adding electric lighting will reduce the
heating load required during winter, but may add to the cooling
load during hotter periods.
—
Transport: the impact the product has by transporting it in terms
of raw materials and by getting it to site, for instance raw
materials made in South America, manufactured into product in
the Far East and then installed in the UK would have a high
transport impact. Similarly, transport to another country or
continent for recycling.
Only by considering the true impact of the use of a product can its true cost be
understood.
2.8
Lighting and
health
Continuing research into the effects of light on health has revealed stronger
links between access to daylight and effects on both the psychological and
physiological well-being of building occupants. These impacts are not yet
sufficiently well understood to safely use electric light to mimic daylight,
therefore the designer should be careful when applying colour and intensity
change for all but entertainment.
In all teaching spaces the use of natural light, regulated only by the season,
weather and time of day is essential, as it the control of this light when blackout or glare reduction is required.
2.8.1
Regulation of the
circadian system
The role of the circadian system (which controls daily and seasonal body
rhythms) is to link the functions of the body (e.g. the sleep/wake cycle, and
changes in core body temperature and in hormone secretion) with the external
day/night cycle. Disruption to this system from lack of light can cause problems
such as depression and poor sleep quality, which could lead to more serious
problems. Therefore, it is important that occupants of buildings are given access
to high levels of daylight, particularly in the mornings, to reinforce circadian
rhythms.
2.8.2
Mood
2.8.3
Seasonal affective
disorder
Mood can be modified by lighting. Daylighting is dynamic and variable and is
strongly favoured by building occupants. Adequate access to daylight can have
a positive impact on mood especially in situations where people are static for
long periods of time.
A small percentage of people suffer a seasonal mood disorder known as seasonal
affective disorder (SAD) with a further number suffering a mild form known as
sub-syndromal SAD (S-SAD). Symptoms include depression, lack of energy,
increased need for sleep and increased appetite and weight gain, occurring in the
winter when there is little daylight. Such symptoms can be reduced by exposure
to daylight.
The ultraviolet (UV) radiation in sunlight can be damaging to the skin.
However, with people spending many daylight hours behind glass in buildings,
there is the danger of insufficient exposure to UV radiation to maintain healthy
levels of vitamin D. A vitamin D deficiency leads to rickets in children and
softening of the bones in adults. The daylight strategy of educational facilities
Lighting options
11
should include periods of outdoor learning throughout the year to counteract
this.
Exposure to sunlight, even through glass, can kill many types of viruses and
bacteria and so can be of great value in winter when there is a high incidence of
respiratory infections.
Recently links have been made between the UV output of some light sources
and damage to skin or sight as a result. Designers should note that the
luminaires they specify must take due account of these risks in their design,
either by use of safe light sources or by other measures that remove any harmful
UV component or limit possible exposure to it. In most cases, for instance
exposure to UV from a conventional fluorescent lamp, there is less risk than
spending a similar amount of time exposed to daylight outdoors, so the user and
designer should not be overly concerned.
3
Lighting
options
3.1
Natural lighting
Fig. 3.1
High level skylights and
windows restrict direct
glare in this daylit atrium
at Brunel University
(photograph courtesy of MID
Lighting)
Evidence from research clearly shows increased learning rates, concentration
and comfort amongst students where there is good daylight within the learning
environment.
Hathaway(26) found significant improvements in health and academic
achievement under full spectrum fluorescent lighting, compared to under cool
white fluorescent or high pressure sodium lighting, in a study of 327 school
children. Mass et al.(27) found that university students doing homework tasks
indicated less fatigue and better visual acuity under a daylight simulating lamp
than under a ‘cool white’ fluorescent lamp.
Two further studies have investigated the effects of daylighting on
children, using primary level schools as the children tend to spend all year in the
same classroom. Küller and Lindsten(28) examined 83 children in four Swedish
classrooms, two with and two without windows. The study measured cortisol,
behaviour, body growth and sick leave over a year, and concluded that
windowless classrooms should be avoided.
Heschong(29) surveyed 8000 to 9000 students in each of three districts
within the US, and reported that students in classrooms with the most daylight
showed a 21% improvement in learning rates (e.g. the change in maths and
reading test scores) compared to students in classrooms with the least daylight.
Lighting options
11
should include periods of outdoor learning throughout the year to counteract
this.
Exposure to sunlight, even through glass, can kill many types of viruses and
bacteria and so can be of great value in winter when there is a high incidence of
respiratory infections.
Recently links have been made between the UV output of some light sources
and damage to skin or sight as a result. Designers should note that the
luminaires they specify must take due account of these risks in their design,
either by use of safe light sources or by other measures that remove any harmful
UV component or limit possible exposure to it. In most cases, for instance
exposure to UV from a conventional fluorescent lamp, there is less risk than
spending a similar amount of time exposed to daylight outdoors, so the user and
designer should not be overly concerned.
3
Lighting
options
3.1
Natural lighting
Fig. 3.1
High level skylights and
windows restrict direct
glare in this daylit atrium
at Brunel University
(photograph courtesy of MID
Lighting)
Evidence from research clearly shows increased learning rates, concentration
and comfort amongst students where there is good daylight within the learning
environment.
Hathaway(26) found significant improvements in health and academic
achievement under full spectrum fluorescent lighting, compared to under cool
white fluorescent or high pressure sodium lighting, in a study of 327 school
children. Mass et al.(27) found that university students doing homework tasks
indicated less fatigue and better visual acuity under a daylight simulating lamp
than under a ‘cool white’ fluorescent lamp.
Two further studies have investigated the effects of daylighting on
children, using primary level schools as the children tend to spend all year in the
same classroom. Küller and Lindsten(28) examined 83 children in four Swedish
classrooms, two with and two without windows. The study measured cortisol,
behaviour, body growth and sick leave over a year, and concluded that
windowless classrooms should be avoided.
Heschong(29) surveyed 8000 to 9000 students in each of three districts
within the US, and reported that students in classrooms with the most daylight
showed a 21% improvement in learning rates (e.g. the change in maths and
reading test scores) compared to students in classrooms with the least daylight.
12
Lighting Guide 5: Lighting for education
They also found no connection between physical classroom characteristics such
as daylight and student health, although this was measured by recording student
attendance, which is not the best indicator of student health.
With this in mind and with the essential drive to design low, or zero
carbon buildings, the strategy for all schools and colleges must be to use daylight
as the primary light source and the building design process should be informed
from the outset as to how that can be achieved. Control of daylight ingress
should be minimised, such that it is reduced or removed from a space only where
privacy, or at specific times when glare or heat gain are issues. In addition where
it is necessary to have dark for experimentation or presentation then daylight
may need to be completely excluded but only for appropriate periods or time.
This of course must be co-ordinated with use of lighting controls and the heating
and cooling design for the building form and early stage in the design.
3.1.1
Design
considerations
Fig. 3.2
Common factors to
consider in daylight
design
Providing a well daylit learning environment requires a design balance between
many factors. As such the daylight and lighting strategy must be developed early
in the design process, where the lighting designer works closely with the
architect and other design team members. Figure 3.2 shows the common factors
that must be considered such that the daylighting strategy delivers the required
solution without negatively impacting on other functional and aesthetic
requirements of the building. Whilst the considerations apply to both new-build
and refurbishment, some design elements will be more difficult to achieve with
refurbishment projects due to existing building orientation and form. However
this does not exclude the designer from reviewing every aspect of the building
and creating the best learning environment achievable.
Legal and
planning
Building
orientation
Building
form
External
building
obstructions
Acoustics
Room
function
Thermal
design
Designing
for daylight
Internal
blinds and
control
End
user
Sunlight
redirection
system
Building
fabric
Shading
systems
Surface
reflectance
Glazing
type
Lighting options
13
3.1.1.1 Building orientation
Understanding the site and the building orientation on the site allows the
placement of room types where the lighting requirements are different, e.g. art
rooms that require a higher level of light as opposed lecture theatres or dance
studios. The façade design can also progress as the availability of daylight is
established and is matched to the requirement of the rooms. Preferred views out
and sight lines can also be established. Refer to the BRE Digest 209: Site layout
and planning for daylight and sunlight(30).
3.1.1.2 Building form
Understanding the form and continuing to progress the façade design allows
more detailed examination of the quality and quantity of daylight that penetrates
the building and individual rooms. A review of both the light and shadows is
required to establish the quality of the light within the building.
3.1.1.3 External building
obstructions
In city centre locations or on more compact sites, external buildings will reduce
the availability of daylight and views. Understanding the quality and quantity of
daylight throughout the building will enable one to advise on adjusting the room
positions, window dimensions, window angles and furniture arrangements to
improve views and daylight levels. The façades of external obstructions also need
to be reviewed to identify if a potential reflection discomfort could occur or if
there is an opportunity to improve the brightness of the building to improve the
view.
3.1.1.4 Room function
Typically, art rooms require more daylight and dance studios or lecture theatres
require less daylight. Equally, some spaces will require balanced light with little
modelling suggesting a northern aspect is preferred. Computer rooms with high
heat loads and high density occupancy could occupy areas within the building
that have limited daylight as this would reduce external heat gains.
3.1.1.5 End users
Different learning environments with their individual types of users will have
some specific requirements from the daylight design. A ‘special education needs’
(SEN) school for example will require that some rooms have few distractions and,
as such, views may be permanently or temporarily omitted. Higher education
students who have more flexibility in their own schedules and travel through a
building will manage their own visual comfort based on their own preferences
and glare from sunlight will likely be less of an issue, although should not be
ignored.
3.1.1.6 Building fabric
The thermal design of the building will drive some elements of the building
fabric and therefore the wall thickness. The wall thickness will affect the
quantity of light which enters the internal space; however it could also act as a
shade to reduce heat gains. Where the building fabric creates a wall thickness of
more than 300 mm then the lighting designer and architect should consider how
to make use of the horizontal element as this could effectively be a light shelf.
3.1.1.7 Glazing
The glass is a critical element in delivering daylight to the internal spaces. As the
façade solution is progressed to satisfy the architectural intent, the daylight and
the thermal requirements of the building, the selection of the glass will be fixed
to achieve a required light transmittance, thermal and solar transmittance. Care
should be taken to ensure the glazing specification is maintained throughout the
design process as value engineering can often deliver alternatives that satisfy, say,
the thermal performance, but significantly reduce the light transmittance. In
selecting the glazing consideration should also be given to the frame
arrangement. Some glazing systems are well designed and utilise small frames
that lead to reduced visual and light obstruction.
The quantity of glazing and the arrangement of glazing will have an
impact both on the quantity and quality of daylight. The sill and head heights
designed to accommodate the end users will deliver good views out and satisfy a
key element in delivering good quality daylight spaces. Figure 3.3 shows the
14
Fig. 3.3
Lighting Guide 5: Lighting for education
Main window types and
daylight distribution
systems
(e) (ii)
(d)
(iii)
(i)
(a)
(iv)
(g)
(f)
(v)
(b)
(c)
main window types and daylight distribution systems employed. These are
described below.
3.1.1.8 Surface reflectance
(a)
Full height glazing: provides very good views out and the maximum level of daylight available through the facade. The high
level glazing delivers light deep into the space thus creating a
visually balanced light distribution. Consideration should be
given to visual security for the lower section of the glazing. Also
if the furniture is placed adjacent to the glazing then the lower
level of glazing will not contribute to the useful daylight within
the space, therefore any analysis should not include the lower
section of glazing.
(b)
Traditional glazing: a solid section of wall makes up the lower
portion of the wall, typically just over desk height, with a solid
upper section downstand element. The glazing is horizontal and
can be full width or broken by solid sections. The downstand
element can impact on light reaching the full depth of the room.
(c)
Internal glazing (‘borrowed light’): internal glazing will provide
views into the atrium as well as secondary daylight via the
atrium. Consideration should be given to the potential
requirement for privacy into the room or to reduce distraction
for some end users.
(d)
Rooflights: the atrium rooflight can provide the quality and
quantity of daylight, both within the atrium and within the
adjacent rooms. The design of the rooflight and any required
shading is critical in achieving the quantity and quality of
daylight.
(e)
Clerestory: clerestory windows provide light from the highest and
brightest part of the sky and will not generally be affected by
external obstructions. They allow a view of the sky but not
typically a view of the immediate outside area. In allowing a view
of the brightest part of the sky the contrast between the inside
and outside is likely to be higher than other window types, thus
likely to cause glare. They will provide light deep into the space.
(f)
Lightwell rooflight: where site constraints limit external facades
and views, secondary light to a space can be provided via a
lightwell. Depending on the depth of the lightwell, the light will
typically be diffuse and glare free. The glazing must be
acoustically sound to avoid noise transfer to adjacent rooms.
(g)
Lightwell window: Semi-translucent glazing can provide a sense
a brightness of rooms via the lightwell daylight.
This is discussed in more detail in section 3.5. The more reflective the surfaces
the more light will be distributed around a space. Selecting which surfaces and
colours requires care to ensure that a balance and visual quality exists within the
space. Window walls should always be light to reduce contrast and thus reduce
the risk of glare.
Lighting options
3.1.1.9 Shading systems
Fig. 3.4
Vertical exterior shading
in use at Cardinal Hume
Catholic School
(photograph courtesy of
Cundall Light4)
15
Many types of shading systems exist and are constructed using a variety of
materials such as wood, metal, glass, mirrors or a combination of these
materials. The units are arranged either as vertical elements or horizontal
elements and fixed to the outside of the building façade. A study of the sun path
across the facades of the building at midsummer, midwinter and the equinox
will show where shading may be required to support other thermal control
devices. The shading devices will typically reduce the quantity of light available
within a space but, designed appropriately for their orientation to the sun, they
will provide a high quality of light within the space. The material selection
should be appropriate to reflect as much light into the space without creating
glare due to high luminance. The devices illustrated in Figure 3.3 are as follows:
(i)
Atria shading: with any large glazed roof, at some period of the
day and year the sun will penetrate the space and, without
appropriate shading, this could be a source of glare (depending
on the use of the space and areas adjacent to the atrium). The
solution could be motorised or manual blinds fixed within the
roof glazing panels, external motorised louvres or internal
louvres. If internal louvres are used these could be combined
acoustic/shading louvres. The orientation, depth, width and
spacing of the louvres will depend on the factors already
discussed in this section, such as building orientation and form.
(ii)
Vertical shading: the shading system comprises vertical ‘planks’
fixed either perpendicular to the façade or at an angle, depending on the design and requirement of the system. The
orientation, depth, width and spacing of the louvres will depend
on the factors already discussed in this section such as building
orientation and form. Vertical louvres are typically used on the
east and west facades of a building to manage the low angle sun
that occurs on these facades. Motorised louvres provide the ideal
control scenario, closing to cut out thermal heat gains when
present and then opening to allow daylight into the space when
the thermal gain no longer exists.
(iii)
Vertically stacked shading: the shading system comprises
horizontal ‘planks’ stacked one on top of another. This
arrangement provides a shading system which sits close to the
building façade. The view out is partially obstructed, depending
on the detail of the shading system. The orientation, depth,
width and spacing of the louvres will depend on the factors
already discussed in this section, such as building orientation
and form. This type of shading system is typically found on the
south façade to manage the high angle sun.
(iv)
Horizontally stacked shading: the shading system comprises
horizontal ‘planks’ stacked one in front of another. This
arrangement provides a shading system which is clear of the
window itself leaving good views out, however it extends out
from the façade making a much more prominent architectural
statement. The orientation, depth, width and spacing of the
louvres will depend on the factors already discussed in this
section such as building orientation and form. This type of
shading system is typically found on the south façade to manage
the high angle sun.
(v)
Lightshelf: the function of a lightshelf is twofold; the first is to
reflect light onto the ceiling and deep into the space, thus
balancing the level of light between the façade and the back of
the room. Secondly, as a large solid component, the lightshelf
affects the thermal properties of a room. The scale of the
lightshelf and materials of which it is composed will depend on
the façade, building orientation and room dimensions.
16
3.1.1.10 Sunlight redirection
system
Lighting Guide 5: Lighting for education
Building components that reflect and direct the daylight can be used both to
provide a visually brighter space and a numerically brighter learning environment. These systems are typically used where there exists difficulty achieving
the appropriate lighting quantity and quality.
—
Fibre optic light distribution: these system use a series of light
collectors either mounted on the roof or walls that feed the light
into fibre optic cables that are routed through the building
fabric to the room in which the light is required.
—
Light pipes: these comprise a highly reflective tube with an
external and internal lens creating a sealed system. The sunlight
enters the top of the unit and reflects multiple times before
being emitted into the room. The greater the diameter of the
light pipe the greater the quantity of daylight that will be
distributed into the room and the greater the length of light pipe
feasible. Bends in the light pipe should be avoided as they
introduce losses.
—
Reflective surfaces: semi-specular material can be used for ceiling
tiles and wall coverings to create areas of higher brightness or
reflect more light into another zone, e.g. on the inside of the
lightwell, the walls can be lined with a semi-specular material to
increase the quantity of reflected light arriving at the ground
floor.
—
Microstructure prismatic materials: this type of material is
manufactured with small prismatic patterns on the surface of a
blind or within a glazing unit, to redirect the daylight to reduce
or eliminate glare. A common use of these materials is in the
upper element of the window system to redirect light onto the
ceiling and thus to the back of the room.
3.1.1.11 Internal blinds and
control
Internal blinds will be required on nearly all external windows and the majority
of internal windows. This will allow control of the daylight to allow viewing of
presentations and videos. The blinds will also offer privacy when required. The
selection of internal blinds is critical as too often they are closed to control glare
and then left closed when, if opened, they would provide a higher quality,
naturally lit, environment and allow the electric lights to be turned off. Blinds
that are easy to control and reliable are more likely to be used. Motorised blinds
are expensive and unlikely to be suitable for general use although may be
appropriate for high level windows in lecture theatres, halls or drama studios.
The transmittance of the blind material should be no more than 10% such that
the sky brightness and sunlight luminance is reduced to a comfortable level.
Some blinds are classed as ‘retro-reflective’, which means they are designed to
reflect some heat gain whilst allowing reflected light through and allowing a
view out. They may be appropriate for some areas where the heat gain is not so
great as to require an external louvre system.
3.1.1.12 Thermal design
Almost all of the components of the building design that affect the daylight
design will also affect the thermal design. It is therefore essential at the earliest
stage of the project to ensure sufficient time is spent examining the most likely
solutions for the site, the building and the spaces within the building. Only
through early discussion between the lighting designer, architect and other
design team members will all of the opportunities to deliver high quality daylit
spaces and energy efficiency be realised.
3.1.1.13 Acoustics
Depending on the building design and selection of building materials,
additional acoustic control may be required within the classrooms and lecture
theatres etc. The position of the acoustic panels/baffles/ceiling tiles must be coordinated with the lighting designer to ensure the installation of the equipment
Lighting options
17
does not interrupt the distribution of the daylight. Typically, if acoustic panels
are to be suspended in a room then an orientation perpendicular to the façade
will have less impact than installation parallel to the façade.
3.1.1.14 Legal and planning
The architect must develop accurate elevation drawings as part of the planning
submission. It is therefore essential to conclude the daylight strategy, assessment
and analysis early in the design process to ensure all window dimensions, frame
details, shading systems and roof lights are shown on the elevation details and
that the building height is fixed. Changes can be costly and may not be feasible
in some circumstances.
3.2
Electric
lighting
There will be times of the year and times of the day when daylight is insufficient, e.g. on a winters evening for adult education. At such times, or where
daylighting is specifically excluded, electric light will need to be introduced.
Designers should consider carefully the provision of electric lighting levels
according to the tables contained in this Lighting Guide (see Table 5.1). Overprovision should be restricted by careful design and by use of suitable lighting
controls that provide for constant illuminance. The addition of electric light to
top-up the daylight should be done carefully, minimising energy use as much as
practical.
Electric light should also be added according to task and, for the major
tasks specifically, it would for instance be sensible to light a standard children’s
classroom to only 300 lux given that it is in use for over 35 hours per week to
teach children, rather than light it to 500 lux simply because it is used for adult
education for one or two hours in the evenings. It should also be remembered
that in most teaching spaces the working plane is rarely simply a horizontal
table surface. The design will have to take into account many vertical and other
non-horizontal surfaces and balance carefully the direction or flow of light. Use
of measures such as cylindrical and cubic illuminance may provide better
indicators of good lighting than conventional horizontal and vertical illuminance or illuminance ratios between a horizontal work plane and other building
surfaces.
3.3
Integrated
daylighting
and electric
lighting
Without doubt, the best lighting designs take account of natural and electric
lighting, balancing one carefully with the other throughout the working day.
Careful design should include electric lighting that reacts to daylight at different
depths into the room and tries to maximise the penetration of daylight into the
space. The designer would do well to think about minimum and average
daylight factors in their design and to relate these appropriately to location and
orientation of the building, or to use alternative sunlight and daylight metrics
such as useful daylight illuminance (UDI). In either case designers must allow for
suitable daylight sensing and dimming luminaires throughout with simple user
friendly controls.
Education buildings are designed to accommodate many diverse
activities in different interior spaces. The successful interior space design
requires that the designer takes into consideration all the requirements and
constraints. Good lighting is an essential part of the interior space design and
without it student and staff activity will be seriously impaired and valuable
energy will be wasted. Good lighting ensures that students, teachers and other
staff can see to carry out their various tasks safely, efficiently and in comfort. It
is important to note that the lighting should not only illuminate the tasks but
must light beyond the horizontal plane and contribute to the quality of the
visual environment and the well-being of the occupants. This needs a holistic or
integrated approach to lighting design considering all criteria and bringing
together daylight and electric lighting solutions in a well-managed operation.
3.3.1
Climate-based
modelling
Climate-based daylight modelling is the prediction of various radiant or
luminous quantities (e.g. irradiance, illuminance, radiance and luminance)
18
Lighting Guide 5: Lighting for education
using sun and sky conditions that are derived from standardised annual
meteorological datasets. Climate-based modelling delivers predictions of
absolute quantities (e.g. illuminance) that are dependent both on the locale (i.e.
geographically-specific climate data is used) and the fenestration orientation
(i.e. accounting for solar position and non-uniform sky conditions), in addition
to the space’s geometry and material properties. The operation of the space can
also be modelled to varying degrees of precision depending on the type of device
(e.g. luminaire, venetian blinds etc.) and its assumed control strategy (e.g.
automatic, by occupant, or some combination). The term ‘climate-based
daylight modelling’ is generally taken to mean any evaluation that is founded on
the totality (i.e. sun and sky components) of time-series daylight data
appropriate to the locale over the course of a year. In practice, this means sun
and sky parameters found in, or derived from, the standard meteorological data
files which contain 8760 hourly values for a full year. Given the self-evident
nature of the seasonal pattern in sunlight availability, a function of both the sun
position and the seasonal patterns of cloudiness, an evaluation period of twelve
months is needed to capture all of the naturally occurring variation in
conditions that is represented in the climate dataset. Standard climate data for a
large number of locales across the world are available for download from several
on-line repositories.
There are a number of possible ways to use climate-based daylight
modelling. The two principal analysis methods are cumulative and time-series.
A cumulative analysis is the prediction of some aggregate measure of daylight
(e.g. total annual illuminance) founded on the cumulative luminance (or
radiance) effect of (hourly) sky and the sun conditions derived from the climate
dataset. It is usually determined over a period of a full year, or on a seasonal or
monthly basis, i.e. predicting a cumulative measure for each season or month in
turn. Evaluating cumulative measures for periods shorter than one month is not
recommended since the output will tend to be more revealing of the unique
pattern in the climate dataset than of ‘typical’ conditions for that period. The
cumulative method can be used for predicting the micro-climate and solar
access in urban environments, the long-term exposure of art works to daylight,
and quick assessments of seasonal daylight availability and/or solar shading at
the early design stage. Time-series analysis involves predicting instantaneous
measures (e.g. illuminance) based on each of the hourly (or sub-hourly) values
in the annual climate dataset. These predictions are used to evaluate, for
example, the overall daylighting potential of the building, the occurrence of
excessive illuminances or luminances as inputs to behavioural models for light
switching and/or blinds usage, and the potential of daylight responsive lighting
controls to reduce building energy usage.
A daylight performance metric would need to be based on a time-series
of instantaneously occurring daylight illuminances because it is important to
capture the full range of illumination conditions to reliably characterise the
daylighting potential of the space. Whilst the practicalities of climate-based
daylight modelling are fairly well understood, it remains to be seen which of the
handful of candidate metrics will be deemed most suitable for compliance
purposes. One of the metrics under consideration is called ‘useful daylight
illuminance’ (UDI). The useful daylight illuminance scheme was devised to
reduce and make readily intelligible the output from a climate-based simulation
without sacrificing the vital performance-revealing content of the raw data.
Rather than analyse the vast amount of simulated illuminance data using
traditional means, e.g. frequency histograms, cumulative plots etc., the rationale
behind UDI was to approach the data first from a ‘human factors’ perspective,
and then reduce it to compact metrics.
Put simply, achieved UDI is defined as the annual occurrence of
illuminances across the work plane that are within a range considered ‘useful’ by
occupants. The range considered useful is based on a survey of reports of
occupant preferences and behaviour in daylit offices with user-operated shading
Lighting options
19
devices. Daylight illuminances from 100 lux to the design level value, say
350 lux, are considered effective, either as the sole source of illumination or in
conjunction with electric lighting. Daylight illuminances from the design level
value up to around 2500 lux are often perceived either as desirable or at least
tolerable.
UDI achieved therefore is the defined as the annual occurrence of daylight
illuminances that are between 100 and 2500 lux. The UDI range is further
subdivided into two ranges called UDI-supplementary (or UDI-s) and UDIautonomous (or UDI-a), taking the design level illuminance as the boundary
between the two ranges. UDI-supplementary gives the occurrence of daylight
illuminances in the range 100 to 350 lux (depending of the design level
illuminance). For these levels of illuminance, additional electric lighting may be
needed to supplement the daylight for common tasks such as reading. UDIautonomous gives the occurrence of daylight illuminances in the range 350 to
2500 lux where additional electric lighting will most likely not be needed. The
UDI scheme is applied by determining at each calculation point the occurrence
of daylight levels where:
—
the illuminance is less than 100 lux, i.e.
(or UDI-f)
—
the illuminance is greater than 100 lux and less than
300–500 lux, i.e. UDI-supplementary (UDI-s)
—
the illuminance is greater than 300–500 lux and less than
2500 lux, i.e. UDI-autonomous (UDI-a)
—
the illuminance is greater than 2500 lux, i.e.
(UDI-e).
UDI
‘fell-short’
UDI-exceeded
For those cases where solar gain in summer must be controlled to minimise
overheating/cooling, careful attention should be paid to the degree of occurrence
of the UDI-e metric.
3.4
Lightness of
the interior
When glancing around a room, people take more notice of vertical or near
vertical planes than of working surfaces. The appearance of an interior is
affected by its general brightness, which depends on the distribution of light in
the room and the lightness of room surfaces. The way in which the space is
illuminated will affect the environment and character of the space and
appearance of objects within. This lighting sets the tone or mood of the space
and gives it atmosphere and prestige, and provides comfort and stimulation for
the occupants. To create a feeling of visual lightness it is necessary to direct light
onto room surfaces, particularly those surfaces that are prominent in the normal
field of view. Often these will be the walls but the ceiling may also be included,
especially in large rooms. Where workstations are employed using vertical
partitions, some light on the partitions will be beneficial and without which the
room can appear gloomy and under-lit. Table 3.1 below gives the range of
illuminance that should be provided on the major surfaces. They will produce
acceptable conditions in most situations. For example bright walls will make a
room appear large and spacious whilst dark walls make it appear small and
cramped.
Table 3.1 Recommended reflectance and illuminance values within an educational space
Room surface
Reflectance
range
Illuminance
Ceiling
Walls
Task area
Floor
0.7
0.5
0.2
0.2
30–90% of task Illuminance or Eh min > 50 lux; Uo > 0.1
50–60% of task Illuminance or Ev min > 100 lux; Uo > 0.1
According to task requirement
Maintained value of 30–50 lux
to
to
to
to
0.9
0.8
0.6
0.4
20
3.5
Lighting Guide 5: Lighting for education
Room surface
reflectance
Room surface reflectance is the ability of the surface to reflect light that falls on
it. The colour appearance of a surface is a function of the surface itself and the
type of light source. It is rare that a lighting designer is allowed to select the
room surface finishes. But when the opportunity arises the designer should
choose the hue (or colour), its lightness or darkness and chroma (or saturation).
Subdued colours are often chosen where a restful or dignified atmosphere is
required, whilst strong colours and high contrast are normally used to create
lively and exciting effects. The recommended reflectance values together with
the preferred range of illuminance are shown in Table 3.1. These values not only
provide for balanced appearance but also help to generate inter-reflected light
making the scheme more energy efficient. Experienced designers will of course
be able to achieve desirable results outside of these limits.
The primary presentation wall, containing the whiteboard, should be of
a different complementary colour and darker hue than the other walls. This
helps to reduce eye strain as the viewer looks from desk to board-based tasks and
back again. Whilst it may be desirable for lighting efficiency to provide higher
reflectance surfaces, a deep tone on one wall will provide visual form to the space
and reduce glare. If the presentation wall is not chosen for the different shade, a
side wall (not the main window wall) should have the complementary or darker
hue.
3.6
Lighting the
interior space
In addition to lighting the task and room surfaces it is important to fill the
volume of space occupied by people with light. It should be remembered that we
see the reflected light from surfaces and hence the choice of colour scheme can
significantly affect the overall impression of the room. The light will need to
illuminate or highlight people and objects, reveal textures and improve the
appearance of people within the space. The preferred lighting conditions can be
described by the terms ‘mean cylindrical illuminance’, ‘modelling index’ and
‘directional lighting’.
3.7
Mean
cylindrical
illuminance
Good visual communication and recognition of all solid objects and especially
people’s faces requires adequate brightness. The objects require light to reach
them from many directions, see Figure 3.5. In essence, the volume of space in
which people move should be filled with light. The requirement can be met by
providing sufficient mean cylindrical illuminance in the space at head height.
In teaching and circulation areas the recommended maintained mean
cylindrical illuminance (Ez) should be at least 150 lux at 1.2 m above floor level
with uniformity of 0.1. Checks should also be made at 0.8 m and 1.6 m above
floor level to ensure adequate coverage for all ages of the educational staff and
students.
3.7.1
Calculation of mean
cylindrical
illuminance
The cylindrical illuminance in a space can be calculated using proprietary
software, often just by selecting the right option so that the calculation surface
or grid calculates cylindrical rather than horizontal illuminance. The grid size
is defined in BS EN 12464-1(31) (due for updating) and also BS EN 12193(32).
Grids approximating a square are preferred; the ratio of length to width
of a grid cell should be between 0.5 and 2. The maximum grid size should be:
p = 0.2 × 5 log d
(3.1)
where p ≤ 10 and is the maximum grid cell size (m), d is the longer dimension
of the area (m) if the ratio of the longer to the shorter side is less than 2
(otherwise d is the shorter dimension of the area).
Lighting options
21
The number of points in the longer dimension is given by the nearest odd
whole number of d/p.
The resulting spacing between the grid points is used to calculate the
nearest odd whole number of grid points in the shorter dimension. This will
give a ratio of length to width of a grid cell near to 1.
A border of 0.5 m from the walls is excluded from the calculation area
except for task areas that are defined and near the wall.
For the immediate surround area the same grid spacing as for the task
area should be applied. For the background the whole room with a border of
0.5 m from the walls, the grid spacing should be in accordance to the room size.
Fig. 3.5
Light falling on the face
from all sides rather than
just horizontally is a
better measure of how
well lit the face will be,
viewed from any direction
This calculation grid should be applied at 1.2 m above floor level,
effectively the seated head height of a typical person. Where the calculation is
applied in rooms predominantly designed for small children, and where
furniture is such that it specifically designed to suit them, it would be wise to
check the corresponding mean cylindrical illuminance at about 800 mm.
Similarly, where the space is designed for teaching where head height is more
commonly at around 1.5–1.8 m, such as for a formal teaching layout with
teaching mainly from a lectern or board, then the mean cylindrical illuminance
at these positions and height should also be calculated.
Approximation of the mean cylindrical illuminance can be made by
calculation the average vertical illuminance at the specified position and height
for each of the four main vertical planes. In this case:
Ez = 0.25 (Ev1+ Ev2 + Ev3 + Ev4 )
3.7.2
Measurement of
mean cylindrical
illuminance
(3.2)
On-site measurement should be carried out at the correct height and to the
method in the Code for Lighting(8) using the grid point spacing as calculated
above and with the use of a cylindrical illuminance photocell mounted and
calibrated against a suitable light meter, see Figure 3.6.
Where there is no possibility of obtaining such a photocell the user
should measure each of the four main orthogonal vertical planes and average the
readings using the formula for Ez above.
3.8
Fig. 3.6
Modelling
index and
directional
light
A typical cylindrical
illuminance measuring
photocell
People, and almost everything else in an interior, are three dimensional and
need to be illuminated all around. Modelling describes the ability of light to
reveal solid form. Modelling may be harsh or flat and the relative strength of
modelling is influenced by the directions from which the light comes and the
direction from which the object is viewed. Fairly strong and coherent modelling
helps to reveal three-dimensional shapes as, for example, in display lighting.
Good modelling is essential to sculpture display and similar purposes, and can
help to reveal the detail of many textured tasks. The effectiveness of the light for
modelling can be defined by the ratio between mean-cylindrical and horizontal
illuminance at the point of interest, see Figure 3.7. A ratio > 0.3 will provide for
adequate modelling; this may be closer to 0.5 for teaching spaces used by
children.
For good modelling there is a need for preferential light to come from one
direction. This directional ‘flow of light’, as produced by daylight through side
windows or asymmetric and batwing distributions of electric light, can create
pleasant highlights and shadows to model objects, texture and people. The flow
of light determines where shadows will be cast and how dense they will be. The
lighting should not be too directional or it will produce harsh shadows, neither
should it be too diffuse or the modelling effect will be lost entirely, resulting in
a very dull luminous environment.
22
Fig. 3.7
Lighting Guide 5: Lighting for education
Examples of modelling
index (photographs courtesy
of Thorn Lighting)
(a) Modelling index = 0.1; highly directional
downlight creates harsh shadows
(b) Modelling index = 0.3; the limit of
acceptable modelling in spaces where good
communication is required and still too harsh
for some children with special educational
needs
(c) Modelling index = 0.5; more appropriate
for children’s classrooms
(d) Modelling index = 1.0; except for theatre
lighting, it is difficult to get an index much
greater than 1.0 and values higher than this
would provide modelling of the face making it
difficult to lip read, for example
4
Lighting
design
guidance
Without doubt natural light should be our primary source of light whenever it
is available in suitable quantity. The links in research to user performance and
comfort and the obvious link to energy saving of electric light are strong and
building designers and architects must include daylight design from the initial
building concept right through to completion and post occupancy evaluation.
However it is difficult to accurately predict daylight contribution using current
metrics such as daylight factor, which does not take into account direct sunlight
components. Those involved in building design should include in their
conceptual design team an expert in daylight design and consider the latest
design tools and metrics to include and predict excellent daylight contribution
throughout all learning spaces. Failure to do so at the earliest stages of design
will result in daylight exploitation being very difficult later on.
Once daylight has been incorporated into the building shape and
orientation then it should be possible to include electric lighting to complete the
overall lighting and lighting controls strategy to ensure learning spaces perform
for both the user and the environment.
4.1
Daylighting
The use of daylight as the main means of lighting is recommended and should
not be compromised in a learning environment, except in circumstances outside
the designer’s control. Sometimes site constraints such as adjacent buildings or
trees will mean electric lighting will be the main source, but the designer should
strive to avoid this. Daylight provides a less stressful environment for pupils and
teachers, improves learning rates and saves energy.
Where we refer to providing daylight within a space we are referring to
both a quality of light and a quantity of light to perform the tasks. The quality
of the light relates to both the direct component (sunlight) and the diffuse
22
Fig. 3.7
Lighting Guide 5: Lighting for education
Examples of modelling
index (photographs courtesy
of Thorn Lighting)
(a) Modelling index = 0.1; highly directional
downlight creates harsh shadows
(b) Modelling index = 0.3; the limit of
acceptable modelling in spaces where good
communication is required and still too harsh
for some children with special educational
needs
(c) Modelling index = 0.5; more appropriate
for children’s classrooms
(d) Modelling index = 1.0; except for theatre
lighting, it is difficult to get an index much
greater than 1.0 and values higher than this
would provide modelling of the face making it
difficult to lip read, for example
4
Lighting
design
guidance
Without doubt natural light should be our primary source of light whenever it
is available in suitable quantity. The links in research to user performance and
comfort and the obvious link to energy saving of electric light are strong and
building designers and architects must include daylight design from the initial
building concept right through to completion and post occupancy evaluation.
However it is difficult to accurately predict daylight contribution using current
metrics such as daylight factor, which does not take into account direct sunlight
components. Those involved in building design should include in their
conceptual design team an expert in daylight design and consider the latest
design tools and metrics to include and predict excellent daylight contribution
throughout all learning spaces. Failure to do so at the earliest stages of design
will result in daylight exploitation being very difficult later on.
Once daylight has been incorporated into the building shape and
orientation then it should be possible to include electric lighting to complete the
overall lighting and lighting controls strategy to ensure learning spaces perform
for both the user and the environment.
4.1
Daylighting
The use of daylight as the main means of lighting is recommended and should
not be compromised in a learning environment, except in circumstances outside
the designer’s control. Sometimes site constraints such as adjacent buildings or
trees will mean electric lighting will be the main source, but the designer should
strive to avoid this. Daylight provides a less stressful environment for pupils and
teachers, improves learning rates and saves energy.
Where we refer to providing daylight within a space we are referring to
both a quality of light and a quantity of light to perform the tasks. The quality
of the light relates to both the direct component (sunlight) and the diffuse
Lighting design guidance
Figure 4.1 Simple rectangular
building designs offer
little scope to temper
daylight (illustration
courtesy of J Mardaljevic)
23
component (skylight). Equally we need to review the quality of the view out of
the space. In providing a view, most people prefer a view of the natural
environment or where this is not possible, e.g. in built-up areas, then a dynamic
view is preferred.
Natural light is very variable and in the past the direct component has
been excluded from the assessment of daylight quality and quantity. The
common measure of daylight has been the daylight factor (an expression of how
much outside light on an overcast day arrives at a particular place in the room),
where the defined luminance distribution of a CIE (Commission Internationale
de l’Eclairage) overcast sky is used in the calculation. Within BS 8206-2: 2008:
Lighting for buildings, Code of practice for daylighting(33), the principle of climatebased modelling is introduced in section 3.3.1
As discussed in BS 8206-2: 2008, climate-based modelling is currently
being developed and, as such, at this time the daylight factor approach to
measuring daylight quantity must be used. However to deliver the best quality
of spaces, the designer should have studied and have experience in designing
spaces utilising sunlight and skylight and controlling these mediums to deliver
bright and well lit spaces. In designing a space with appropriate daylight we are
providing a space that allows the reduction in use electric lighting during
daylight hours. The savings from automatic dimming controls are directly
related to daylight factor. As discussed previously, the building form, materials,
glazing, façade etc. will affect the daylight factor.
As far as space planning is concerned, natural lighting and natural
ventilation are in sympathy. The maximum depths of spaces for natural
ventilation are comparable to the maximum depths for effective daylighting.
The depths of individual classrooms should generally be limited to
around 7 m. Beyond this, greater ceiling heights (>2.7 m), skylights, light wells,
clerestory windows etc. will need to be employed to improve daylight
penetration. To ensure the focus on daylight as the primary source of light in all
educational spaces it will be preferable to include the above elements in all
possible cases.
A ‘well tempered’ daylit environment is one where the fixed architectural
form provides both good daylighting and effective solar protection. Thus
minimising — though in practice rarely eliminating — the need for occupants
to close blinds/shades.
The potential for the fixed form to temper the daylighting of the space
depends on the building type, specifically on the richness/variety of the fixed
architectural form. For simple rectangular office blocks (Figure 4.1), the scope
to temper the daylit environment is limited to a few basic building parameters
such as glazing ratio, window transmissivity etc. Optimisation of these will have
some beneficial effect, but the occupants will still have to resort to frequent use
of the blinds/shades to prevent undue ingress of daylight and to prevent glare.
The greater the richness and variety in the architectural form (e.g. brise soleil,
atria, self-shading etc.) the greater the opportunity for tempering the daylit
environment through an integrated design approach that combines effective
solar control with good daylight practice. Often the more successful daylighting
designs are those that offer a combination of daylighting strategies. Low-rise
buildings such as schools (Figure 4.2) offer the greatest opportunity to realise a
‘well tempered’ daylit environment because the designs can, in principle,
accommodate various daylighting features/devices. In addition to the brise soleil
and atria noted above, imaginative low-rise building designs can also feature
skylights, clerestory windows, light-wells, re-entrant sections, overhangs, deep
self-shading reveals etc.
Window areas and ceiling heights should be chosen to achieve high
daylight factors because the benefit of carbon savings is so significant that the
extra cost of larger windows and high ceilings may be effective in terms of cost
of carbon abatement compared to renewables. They will also aid natural
ventilation.
24
Lighting Guide 5: Lighting for education
Figure 4.2 Lower level architectural
forms can combine
effective solar control
with good daylight
practice (illustration
courtesy of J Mardaljevic)
In all cases where daylight introduces a high thermal load the designer
should consider carefully the options. The inclusion of interior and exterior sun
control is an option that should be considered, carefully linked to all the other
factors. Its removal on cost grounds is not acceptable if that decision makes the
use of daylight impractical because of its implications for ventilation design and
acoustics. In urban and rural locations where noise and air pollution are not
significant, daylight design must take priority with a higher degree of natural
ventilation used to offset heat gains. In city locations where noise and air
pollution may be considerable, the daylight quantity may have to be reduced to
allow suitable ventilation strategies. However it should be remembered that
often in built-up locations daylight itself will be restricted by surrounding
buildings and the designer should take this into account.
4.1.1
Daylight quantity
Fig. 4.3
Deep central atrium
providing daylight to first
floor classrooms with ICT
break-out class on lower
floor (photograph courtesy
of Corby Academy; Foster &
Partners)
Fig. 4.4
Average and minimum
daylight factor should be
calculated up to 0.5 m
from each wall
The average daylight factor is used as the measure of general illumination from
skylights. To achieve the appearance that a room is predominantly daylit the
average daylight factor should be at least 2%. If the average daylight factor in a
space is at least 5% then electric lighting is not normally needed during the
daytime, provided the uniformity is satisfactory. If the average daylight factor in
a space is between 2% and 5% supplementary electric lighting is usually
required.
The strategy should be to create spaces that are daylit to improve learning
rates and reduce energy consumption. Therefore good practice would be to
achieve 5% average daylight factor and a minimum point daylight factor of 2%.
When measuring the average and minimum values it is recognised that
directly adjacent to walls the daylight level will be at its minimum and if used
will disproportionally represent the daylight distribution within the space.
Therefore it is recommended to leave a 0.5 m zone around the perimeter of the
space to eliminate these values (see Figure 4.4). As with all calculations, due
consideration has to be given to furniture layouts. For example, if it is known
(and the question should be asked) that desks or task areas will be positioned
directly against the walls of the room, then the 0.5 m zone should not apply.
The various types of spaces within a school, college or university will
require different lighting strategies, e.g. a drama space, sports hall, art room or
lecture theatre etc. will have specific needs such as mirrored walls, solid walls
and north lights, blackout etc. As such, the 5% average and 2% minimum good
practice design must be balanced against these specific needs. However, for
general teaching spaces, as discussed previously, only external factors outside
0·5 m
0·5 m
0·5 m
L
H
0·5 m
W
Lighting design guidance
25
the designer’s control would justify daylight factors less than the good practice
figures.
The importance of the uniformity cannot be underestimated. Too high a
contrast and a space will look gloomy from some positions and viewpoints and
be visually uncomfortable or distracting. Controlling uniformity requires the
access of daylight and distribution of daylight within the room to be balanced.
Measures that easily identify if this will be achieved include the ‘no sky line’ and
room depth criteria. Calculating the daylight factors throughout the space,
either manually or by computer, is also appropriate. These methods are
discussed below.
The figures recommended here aim to improve the learning spaces that
are currently constructed in the UK and, as such, aim to push design forward
and ensure designers recognise the value of daylight to the staff and pupils
within the learning environment.
A procedure for calculating the average daylight factors is given in BS
8206-2: 2008(33) and can be used to calculate the average daylight factor targets
given above.
4.1.1.1 Calculating daylight
factor for windows
and rooflights with
continuous
obstructions of
uniform height
When external obstructions can be defined adequately by two horizontal lines,
i.e. the upper and lower limits of the visible sky, the average daylight factor on
––
the working plane ( D), expressed as a percentage, is:
T Aw θ
––
D = ————–
A (1 – R 2 )
(4.1)
––
where D is the average daylight factor on the working plane (%), T is the diffuse
light transmittance of the glazing including the effects of dirt (see BS 8206-2:
2008(33), section A.1.2 for typical figures), Aw is the net glazed area of the window
(m2 ), θ is the angle subtended by the visible sky (degrees) (measured in a vertical
plane normal to the glass, from the window reference point, see Figure 4.5), A is
the total area of the ceiling, floor and walls, including windows (m2) and R is the
area-weighted average reflectance of the interior surfaces (in initial calculations
for rooms with white ceilings and mid-reflectance walls, this may be taken as
0.5).
Fig. 4.5
Angle of visible sky
Window
reference
point
0°
When two or more windows in a room face different obstructions, or
differ in transmittance, the average daylight factor should be found separately for
each window, and the results summed.
To find the window area above the working plane, in square metres,
needed to achieve a given average daylight factor, the equation may be inverted,
as follows:
––
D A (1 – R 2 )
Aw = ————–––
Tθ
(4.2)
26
Lighting Guide 5: Lighting for education
Note that the window area below the working plane does not significantly
increase the amount of daylight falling onto the working plane. This is because
the light from the lower part of the windows has to bounce off at least two room
surfaces before it reaches the working plane, and it is also common for there to
be obstructions below the working plane. A study has shown that the area of the
window below the working plane is only about 15% as effective at letting light
onto the working plane as an equivalent area above the working plane.
Limitations of the formula: Equations 4.1 and 4.2 should not be applied where
external obstructions cannot be represented by a single angle of elevation, for
example where a window faces into a courtyard. For further information, see
BRE Report: Site layout planning for daylight and sunlight: a guide to good
practice(34) and Modification of the split-flux formulae for mean daylight factor and
internal reflected component with large external obstructions(35).
4.1.1.2 Room depth criteria
This section recommends a procedure for calculating the maximum depth of a
side-lit room.
In a room with windows in one wall only, the following inequality should
be satisfied:
L
L
2
—+—<
———
–
–
W H
1 – Rb
(4.3)
where L is the depth of the room from window to back wall (m) (see Figure 4.6),
W is the width of the room, measured parallel to the window (m) (see Figure
4.6), H is the height of the window head above floor level (m) (see Figure 4.6)
and Rb is the area-weighted average reflectance of the interior surfaces (walls,
floor and ceiling) in the half of the room remote from the window.
Fig. 4.6
Limiting depth of a side-lit
room
L
H
W
4.1.1.3 No-sky line
The no-sky line divides those areas of the working plane which can receive
direct skylight from those which cannot. If a significant area of the working
plane lies beyond the no-sky line (i.e. it receives no direct skylight), then the
distribution of daylight in the room will look poor and supplementary electric
lighting will be required. The working plane height is relative to the tasks being
undertaken, e.g. desk height. At least 80% of the working plane should have a
view of the sky.
4.1.2
The view through a window, or how we perceive the world outside, is a dynamic
experience associated with changes in skylight, sunlight and season. At its lowest
level, a view satisfies the physiological need of the eye for a change of focus, and
provides an awareness of the environment beyond the building.
View will depend on the location, size, shape and detailing of the window.
However stimulating the exterior may be, windows that are too small, break up
the view, or are at a height that inhibits view from normal positions are less
desirable. There are some spaces where external view may be considered
Daylight quality and
view
Lighting design guidance
27
inappropriate as, for example, in a lecture room or theatre where the aim is to
encourage occupants to concentrate solely on the task in hand. Nevertheless,
there is a general presumption that a view through a window is good, and a
daylight strategy that denies a view in any building needs to be questioned. In
buildings comprising very large spaces, internal views to other daylit areas may
suffice. However in all classrooms a view to the outside should be considered
mandatory.
The view out must be balanced by privacy and the need to keep the
students’ attention. Low level glazing may require privacy glass, and rooms for
teaching that look out onto particularly busy environments may need careful
view control to remove visual distraction (see Figure 4.7).
The question of privacy can be addressed by using curtains or blinds that
have the benefit of avoiding the ‘black hole’ appearance of the window at night.
They also provide a means of reflecting electric light back into the room rather
than losing it to the outside, but this will require a moderately high reflectance
of the inside surface and will dramatically affect daylight contribution. Care
should be taken to specify materials that reduce daylight glare where needed or
eliminate it if complete darkness is required. This need for control for purposes
such as interactive whiteboard or image projection should be balanced carefully
with the benefits of having some daylight and view present during daytime
hours.
Fig. 4.7
Top: the classroom shown
uses a radiant heating
panel to provide privacy
but this also reduces
slightly the daylight
contribution from the
windows
Bottom: in this classroom
desperate measures have
been taken either to
reduce glare or view at
the rear window, where
blinds are not available
28
Lighting Guide 5: Lighting for education
Fig. 4.8
Variability of daylight
across the room is
desirable (photograph
courtesy of Thorn Lighting)
Fig. 4.9
Internally glazed walls
allow daylight
contribution, a link to the
outside conditions and a
distant view (photograph
courtesy of Philip Smith)
4.1.3
Glare and sunlight
control
Care should also be taken in specifying blinds that do not disrupt the
ventilation strategy. For opening windows, a common strategy is to fix the blind
to each window such that the window can be opened and the blind move with
the window, thus allowing the required air flow.
The quality of the view is clearly of importance. Some views are of
exceptional beauty and provide pleasure in themselves, and any experience of
the world beyond the window that extends our perception of space should be
considered good. In addition to providing the right quantity of light, daylight
gives an interior a particular unique character. Some of this is due to the
variability of the daylight including sunlight; also, the distribution of the light
enhances the visual field. The directional properties of light from side windows
(the ‘flow of light’ across the room) are a significant attribute contributing to the
modelling of the interior, including objects within it and surface textures, and
providing brightness to vertical surfaces, the amount depending on the reflectance. Some variability across room surfaces is also important (see Figure 4.8).
Wherever possible, the shape, size and disposition of the windows should
be related to the view, and avoid any deprivation or curtailment of it by their
position, height or width. A minimum glazed area of 20% of the internal
elevation of the exterior wall is recommended for a view. Any serious
obstruction to the view can be annoying and appropriate sill and head heights
are important (see Figure 4.7).
While the view out should preferably have close, middle and distant
components, and contain some natural elements, frequently this is not possible
and a popular alternative is the use of courtyards. For these to be successful, they
must be well maintained, preferably with suitable landscaping and some views
of the sky, and have an adequate view dimension across the courtyard of not less
than 10 m.
In some instances, a reasonable view of the exterior may not be feasible,
and in these cases a long internal view is a useful addition — within a large space
or possibly through glazed partitions. However, it is preferable to have a feeling
of ‘daylight contact’ maybe from roof lights and including atria (see Figure 4.9).
On some occasions, a view out can be a disadvantage and cause distraction, and
in these circumstances, blinds or curtains should be provided. In addition, there
are situations where there is a need for privacy and here the view into the
building needs to be considered.
External shading such as blinds or brise soleil are particularly effective in
reducing solar gain. Mid-pane blinds are also very effective. Internal shades or
blinds will reduce internal gains but are less effective because once solar
radiation has penetrated the glass it will cause some heating of the interior of the
building. The blind finish is important; reflective blinds may (with clear glass)
reflect heat back out, while absorbing blinds and curtains will become warm
quickly.
Fixed devices require careful design for the site to avoid reducing
daylight which could lead to increased use of electric light. Adjustable devices
have the advantage of allowing maximum daylight penetration while providing
sun shading when required. They can be controlled manually or automatically.
Manually adjusted blinds or shades can be set by the occupant as required, but
there is a tendency for them to be left down which results in unnecessary use of
electric light (see Figure 4.10). Automatic blinds overcome this problem, but
special attention needs to be given to their control to avoid user annoyance with
frequent movement of the blinds. They also need to be silent in operation, and
particular attention needs to be paid to automatic blinds where maintenance is
concerned.
With internal blinds, it is important to take into account potential
problems that could undermine their effectiveness. Such problems include
interference with the open window, restricting natural ventilation air flow, blind
rattle or sway in the airflow, blinds positioned too far back from the pane
Lighting design guidance
Fig. 4.10
Blinds closed to reduce
glare requiring electric
lighting though the class
is empty (photograph
courtesy of Thorn Lighting)
Fig. 4.11
Types of external
(numbers 1–10) and
internal (numbers 11–15)
shading devices
29
allowing sunlight to fall on the interior window ledge or poor, inaccessible or
inconvenient user controls.
Figure 4.11 shows various types of external and internal shading devices.
Detailed descriptions and application advice for each of these shading devices
can be found in SLL Lighting Guide LG10: Daylighting and window design(15).
Designers should be careful in the selection of interior shading devices
and the colouration/pattern of the materials used. In recent research the
provision of blinds in 23% of classrooms had spatial characteristics appropriate
for inducing pattern glare(36) which can be a particular problem to those who
suffer from dyslexia and migraine headaches.
One of the most important aspects of obtaining a satisfactory interior
environment is to provide a balanced luminance distribution — some contrast
but not excessive. If the luminance of the sky seen through a window is very
high and close to the line of sight of a visual task of much lower luminance,
disability glare can occur due to a reduction in the perceived contrast, making
details impossible to see and thus reducing task performance.
Disability glare will occur where there is a window in a wall on which
there is a whiteboard and this must be avoided.
Discomfort glare is experienced when some parts of an interior have a
much higher luminance than the general surroundings and this may take some
time to become apparent. Discomfort glare from daylight can be a more
common occurrence than disability glare, and under most circumstances its
degree will depend not on the window size or shape, but on the luminance of the
sky seen in the general direction of view. Data suggest that, for the UK, an
unprotected window will produce uncomfortable glare over a significant period
of the year. It has been predicted that skies with an average luminance exceeding
8900 cd/m2 (corresponding to a whole-sky illuminance of 28 000 lux) will cause
discomfort glare, and in the UK these are experienced for about 25% of the
working year. Teachers recognise that discomfort glare from daylight and
windows impinges directly on student concentration citing the phrase ‘when the
lighting is bad the students stop listening’, hence designers should take great
care to control overall window luminance.
1 Horizontal
projection
2 Fixed vertical
projection
6 Pivoted non7 Vertical nonretractable louvre
retractable
woven mesh
11 Venetian
blind
12 Vertical louvred
retractable blind
3 Fixed vertical
screen
8 Retractable
louvred blind
13 Fabric roller
blind
4 Fixed louvre
system
9 Projecting
awning or
sun blind
14 Fabric
curtain
5 Fixed
horizontal
10 Vertical roller
blind
15 Venetian blind
in double window
30
Lighting Guide 5: Lighting for education
Some reduction in the sky glare can be achieved by reducing the contrast
between the window and its surroundings, for example by the use of splayed
light-coloured reveals or increasing the brightness of the window wall by
increasing its reflectance, or lighting it from a window in an adjacent wall.
Window frames should be as light in colour as possible, whether stained or
painted timber, or painted or integrally coloured metal or plastic. However, the
reduction of the sky luminance is the major consideration, and where this is
likely to be a problem provision should be made for blinds (e.g. horizontal or
vertical louvre blinds) or curtains (which can be translucent or opaque, and
internal or external), or retractable screens, canopies or awnings. Permanent
features such as roof overhangs may also assist in this matter. However, it has
been shown that in the UK, overhangs of more than 300 mm over windows
serve little purpose in terms of shading or improved daylighting(37). If the
underside of the overhang is light in colour, the penetration will be improved
and excessive contrast with the sky can be avoided.
Rooflights can cause discomfort glare for most of the working year if the
glazing can be seen directly from normal viewing positions at angles of less than
35° above the horizontal (see Figure 4.12). The glare can be ameliorated by using
measures similar to those for vertical windows (see Figure 4.13).
Fig. 4.12
Skylight panels in the
field of view can cause
discomfort glare
0<35°
Fig. 4.13
Shading styles similar
vertical glazing can be
used to reduce glare
0<35°
Contrast between the glazing and its surroundings can be reduced by
using coffers with high reflectance sides which also cut off the view of the direct
sky and by setting the rooflight in a light-coloured ceiling. The luminance of the
sky seen can be reduced by adjustable blinds, shades or louvres. The use of a
permanent diffusing panel to close in a coffer at ceiling level can provide
unsatisfactory conditions; it may become difficult to appreciate that the source
of light is natural and the feeling of ‘daylight contact’ may be lost, particularly if
the exterior glazing material is also diffusing. Further, on dull days, there will be
a noticeable reduction in the amount of contributed light.
While most of the time sunlight is considered to be an amenity in this
country, there are occasions particularly in the summer months when it is
necessary to provide some protection from its inconveniences, such as excessive
direct heat and glare, and shading devices are required. These can usually be
designed in conjunction with the devices considered for the reduction of sky
glare.
Lighting design guidance
31
It may be undesirable, depending on the climate, to design permanently
fixed features because they will reduce the amount of daylight entering the room
at all times and this could be particularly undesirable in the winter months.
The protection can be provided by adjustable screening devices such as
curtains and blinds including louvre blinds (Figure 4.11, types 11–15). For
optimum sun protection, the solar control devices should be placed outside the
window; retractable screens, canopies or awnings can be used here (Figure 4.11
types 1–10). In designing a sunlight control system, it is important that it takes
into account the extent of the use of the school during the summer months.
4.2
Electric
lighting
4.2.1
Glare
α
Fig. 4.14
Lamp shielding angle, α
Emphasis on glare from electric lighting has for a number of years been focused
on the requirements of Lighting Guides LG3(38) and LG7(39), where designers
have focused on reducing glare in computer display screens. Technological
advances have made some of these recommendations obsolete and designers
would be well advised to absorb the most recent guidance and research before
reaching a definition of suitable glare limits.
The design should also consider that the majority of learning is
supported by computers, but not taught via computers; hence the reduction of
glare to computer screens whilst growing in importance is not an over-riding
factor in most classrooms or lecture theatres. Use of computers will undoubtedly
increase over the next decade but their use in the majority of cases will be
limited, interrupted by other styles of learning, conventional teaching, and for
limited periods. Whilst considering glare to display screens, designers should
focus on providing glare control that improves the modelling and lit appearance
of the true teaching surface: the face (teacher, lecturer, student or pupil), text,
wall displays and presentation board.
Long established calculations for unified glare rating (UGR) may provide
the designer with a numerical method for calculating glare, but the designer
would do well to consider the issues rather than meet a minimum number. Glare
calculated at the mid-position of each wall looking from a seated position may
indicate a worst case but does not apply well to users who are standing, users of
different ages and heights, flexible class or teaching layouts or other teaching
spaces outside the norm such as raked lecture theatres. Current research is
looking to offer alternative measures for glare using high dynamic range
imaging converted to luminance maps, though this is still some way from
providing useful metrics.
Light sources of high luminance and smaller sizes, including smaller,
more intense optics, will need careful consideration so that the light source
luminance is not so intense that even at a small size it impinges on a clear and
comfortable view of the users. This can be achieved by specifying the minimum
shielding angles in the field of vision given in BS EN 12464(31) for the specified
lamp luminance, see Figure 4.14. Minimum shading angles for a range of lamp
luminance values are given in Table 4.1.
The values given in Table 4.1 do not apply to uplighters or to luminaires
mounted below normal eye level.
Table 4.1 Lamp shielding angle limits
Lamp luminance
(kcd/m–2)
Minimum
shielding
angle, α
20 to < 50
50 to < 500
–> 500
15°
20°
30°
32
Lighting Guide 5: Lighting for education
4.2.2
Flicker and high
frequency operation
Research clearly shows flicker from fluorescent and discharge light sources
powered by switch start or wire-wound gear does influence the comfort of a
significant proportion of the population. To avoid discomfort and hence increase
concentration and learning rates, the designer should specify high frequency
(HF) unless there is a specific special educational need for other systems. Care
should be taken that all control gear should conform to the targets set by the
Energy-using Products Directive(17) and, in the UK, by the Ecodesign for
Energy-Using Products Regulations(40).
Advances in high intensity discharge gear mean that HF gear is becoming
more readily available for these light sources. Where practical and efficient, HF
gear should also be used in these applications.
Where the room being lit contains high speed machinery, such as
machine rooms for engineering, industrial technology, or design technology
spaces in schools, then HF equipment must be specified on grounds of safety.
Here the fast moving machines combined with switch start gear can create
stroboscopic effects that may make the work appear stationary. HF gear operating
at above 30 kHz should minimize this risk. Even so, the designer should carry
out a risk assessment of the processes concerned to ensure that the lighting will
not add to any inherent danger.
Care must be taken with the specification and use of LED light sources
and associated drivers where some poorly designed units have been seen to
introduce an over-riding 100 Hz ripple onto the mains, which may be visible to
some users.
4.2.3
Veiling reflections
Veiling reflections are high luminance reflections that overlay the detail of the
task. Such reflections may be sharp-edged or vague in outline but, regardless of
form, they may affect the ability to see the task and cause discomfort. Task
performance will be affected because veiling reflections usually reduce the
contrast of a task, making task details difficult to see.
The two contributors to veiling reflections are any part of the task that is
glossy to some degree, and parts of the interior that have a high luminance, such
as windows or luminaires. Generally methods of avoiding veiling reflections are
to use matt finishes or to arrange the geometry of the view so that high
luminance is restricted, for example by using curtains or blinds on windows.
Gloss finishes should be used with care as they can cause veiling
reflections and glare and often when least expected, for instance the use of a
gloss whiteboard, designed for written presentation but used as a projection
screen. Here the lamp from the projector itself can become a major source of
veiling reflection and discomfort glare to students seated at many positions
within the room.
This is less of a problem in most indoor spaces but small intense light
sources such as computer projectors or uncontrolled luminaires such as
spotlights can give problems. Such glare will manifest itself in veiling reflections
on whiteboards, glossy computer screens and glossy pages in books.
The primary complaint in classrooms about visual conditions is that of
reflections in display screens(41). This extends to a wider range of media than
just computer screens. Modern classrooms have for some time used gloss
finished whiteboards rather than chalk-based black or green boards. Inherently
the gloss finish is susceptible to veiling reflections that make it difficult to see
the writing on the board from certain angles. While this problem can be
controlled by the electric lighting, daylight plays a much larger role and suitable
control of the luminance from a window will be necessary. Extending this to
current technology, it is necessary to include interactive whiteboards dealing not
just with the written message, but projected images as well.
Whiteboards, like green and blackboards before them, require careful
lighting. Luminaires placed in the offending zone may cause veiling reflections
for pupils, so position and control is important. Windows should not be
provided in either the front wall or back wall of a lecture theatre or lecture room.
Lighting design guidance
33
The former would produce intolerable glare to the audience and the latter would
cause serious veiling reflections on the board.
4.2.4
Luminance
distribution
Fig. 4.15
Classroom exploiting the
use of colour (photograph
courtesy of Concord (Havells
Sylvania) and Redshift
Photography)
The luminance distribution in the field of view controls the adaptation level of
the eyes, which affects task visibility. A well balanced adaptation luminance is
needed to increase the visual acuity (sharpness of vision), the contrast sensitivity
(discrimination of small relative luminance differences), and the efficiency of
the ocular functions (such as accommodation, convergence, pupillary
contraction, eye movements etc.).
The luminance distribution in the field of view also affects visual comfort
and there are a number of problems to be aware of. Too high luminance may give
rise to glare; too high luminance contrasts will cause fatigue because of constant
re-adaptation of the eyes. Too low luminance and too low luminance contrasts
will result in a dull and non-stimulating working environment. This can be as
much an effect of the light distribution in a space as the choice of colours used
on the major surfaces.
Figure 4.15 shows a typical classroom where colour is used in the field of
view to add interest to an otherwise bland space. Light surfaces, even the floor
contribute to the overall brightness of the room.
The luminance of all surfaces is important to create a well balanced
luminance distribution, and will be determined by the reflectance and the
illuminance on the surfaces. Recommended reflectance for the major interior
surfaces are discussed in section 3.5. In addition, the reflectance of major objects
(e.g. furniture, machinery etc.) should be in the range of 0.2 to 0.7.
The surfaces within the room should be effectively lit. For spaces where
communication is less important the maintained illuminance on the walls
should be ≥50 lux with uniformity >0.1; maintained illuminance on the ceiling
should be ≥ 30 lux with uniformity of 0.1.
Applications or activity areas such as offices and teaching areas, where
facial recognition and communication are much more important, need brighter
surfaces. Here the recommended maintained illuminance for walls should be
≥ 100 lx and for ceilings ≥ 50 lx.
The designer should consider that illuminance over the complete wall
surface will contribute to the illuminance in the field of view and should be
considered carefully as a whole.
34
4.2.5
Lighting Guide 5: Lighting for education
Choice of lamp and
luminaire
It is impossible using known technologies to match artificially the properties of
daylight. Given the fixed spectrum of all light sources it is not possible to match
the change in sky colour through the day or at different locations with the
movement of the sun in azimuth and elevation.
Even the latest red, green, blue colour mixing techniques using LEDs
cannot match the colour content in terms of spectrum; the best that can be
achieved is to fool the psyche into thinking that the artificial solution comes
close. The appearance of a lighting solution or lamp with a colour temperature
close to that of light from a clear sky at midday may seem excessively blue as
evening approaches. The light is also coloured by the materials outdoors from
which the light it reflects before entering through the window.
Discrepancies between the colour of electric light and that of daylight can
be reduced by:
(a)
using lamps of cool or intermediate correlated colour
temperature (CCT) class of about 4000 K, or
(b)
by screening the lamps from the view of occupants.
Caution: research is continuing into the effects of biodynamic lighting on people
and, until firm research suggests no long-term risk, the lighting designer should
be wary of unsubstantiated claims.
4.2.6
Lighting control
It becomes apparent to anyone who walks around educational buildings that
lights are often switched on in places that have more than adequate daylight.
Were lighting to be turned off, the occupants would often not notice the
difference. In considering dimming and controls the reasons for switching
lights on must be understood. This may be for a number of reasons such as:
—
All lights are turned on because the row of seats furthest from
the windows is at a lower level of illumination than the window
seats, and the lights are turned on to equalise the illumination.
—
The lights were turned on first thing in the morning and, as the
day brightens up, the teacher has not noticed they are still on.
—
Clouds passing have caused brief interludes of dimness that have
prompted the teacher to turn lights on.
—
Glare from the windows has caused the shades or curtains to be
drawn
—
Daylit spaces adjacent to classrooms (e.g. corridors) are brightly
illuminated and the classroom appears relatively dim on
entering.
Lighting design should make the maximum use of daylight and be
divided into zones of control relative to the amount of daylight present. Using
electric light to complement daylight should be considered only when daylight
is insufficient, and designers should ensure energy efficient electric lighting that
only operates when it is required (see Figure 4.16). This last point can be
covered by the positions of the control devices, by the organisation of the
lighting circuits to relate to the daylight distribution and to the function of the
space.
Automatic controls can provide significant energy savings but it is
essential that any controls are ‘user friendly’, and should be based around
automatic daylight harvesting where daylight is sufficient and absence control
to spaces where lighting is likely to be left on. Absence control requires the user
to make the decision to turn on lighting locally and switching circuits and
positions should be included with this in mind. Careful design here will reap
maximum energy savings, minimise control circuit power losses and provide the
user with consistent functionality.
Lighting design guidance
Fig. 4.16
35
Daylight sensing controls
barely visible in the
ceiling centre hold off the
artificial lighting during
times when sufficient
daylight is available.
(photograph courtesy of
Thorn Lighting)
There is extensive evidence that users do not like or use complex control
systems, hence the designer should keep it simple, avoiding complex building
management linked systems (that may be beyond the comprehension of staff
and pupils) and use controls that are intuitive in operation and easy to learn.
‘Scene setting’ controls should be used only where absolutely necessary,
for instance in conference facilities and lecture theatres, but even here should be
limited where possible to a number of simple, practical scenes operated by clear
and practically located control panels.
In all cases lighting controls should be commissioned (see CIBSE
Commissioning Code L: Lighting(42)) by a suitably qualified person and adequate
training given to users.
4.3
Integrated
daylight and
electric
lighting
In educational buildings most of the spaces should be predominantly daylit,
with electric lighting taking over on dull days and at night. There may however
be some spaces that have some daylight, but not always sufficient over the whole
area. In these cases, it will be necessary to employ a system combining both
daylight and electric lighting, which is used as and when required. It is
necessary to consider the distribution of daylight together with the complementary electric lighting distribution to ensure they enhance one another.
However, it will not be sufficient to provide a combined lighting system that
gives only a uniform horizontal plane illuminance. It will also be necessary for
the electric lighting installation to create the sensation of brightness in the areas
remote from the windows. For this it will be necessary to highlight surfaces,
particularly the walls.
When the daylight recommendations cannot be achieved throughout the
space, a supplement of electric lighting should be provided, but it is usual to
require the space to appear predominantly daylit.
The first requirement is for the electric lighting to supplement the
daylight so that the combined illuminance is suitable for the task or activities
being undertaken, and an effective use of controls is necessary to limit the
electric light to no more than is required.
To achieve a satisfactory appearance the luminance of surfaces should be
balanced throughout the space so that surfaces in parts remote from the
windows do not seem dim and gloomy. An appearance that is visually acceptable
can be achieved by preferentially lighting the wall remote from the windows
with lighting that is separate to that required for the task. This wall lighting can
be more effective when some variety is incorporated, as described in section
4.2.4. The ceiling will also need to be well lit to avoid a gloomy appearance. Care
should be taken when this wall is partly glazed and open to an atrium or
corridor.
36
Lighting Guide 5: Lighting for education
Bare lamps should, wherever possible, be screened from direct view (see
Table 4.1) to reduce glare and to limit the variation that can occur in the colour
appearance of daylight. With regard to discomfort glare for combined
installations, and to ensure the degree of glare from the two installations
operating together is acceptable, it is advised that independently each
installation should be designed to be within acceptable limits.
4.4
Aids to
lighting design
Whilst designing with numbers has its place in quantifying the performance or
efficiency of a space, quantifying the lit appearance, the comfort factor is much
more difficult. As an aid to developing this aspect of design, the designer should
use a number of techniques enabling the design possibilities to be iteratively
explored and proved. These methods could include computer-based modelling
and architectural models, particularly for daylight and sunlight studies, but also
to understand the play of electric light in a space.
Architectural models were commonly used to explore daylighting
designs, but are often expensive and difficult to achieve given the demands on
specialist equipment and model making; further iterations of models may make
this impractical. However they do render daylight as perceived and viewed by
the eye and therefore are easy to interpret. Computer visualisation (see Figure
4.17), whilst easier to achieve given current technology, is more difficult to
interpret, the results being only as good as the software algorithms and the
display ability. For example, in order for the screen to render the difference
between two joined white surfaces, software is forced to render two versions of
grey, where as the eye would actually see two whites of differing luminance.
For this purpose it is advised that a scale of not less than 1:20 be used and
that models are made from materials that are opaque and have the appropriate
surface reflectance and colour. It is obviously important that models are dimensionally correct and that any external obstructions are included. The depth of
detail that should be modelled will depend on the purpose of the modelling
study and it may or may not be necessary to model, for example, glazing bars.
However, where measurements are to be taken, then items such as glazing bars
must be taken into account. It is important to include any permanent shading
devices including roof overhangs. Using the correct material finishes, and in
particular for any shading device, is critical where measurements will be taken.
Also external obstructions and their reflectance should be modelled.
The model can be used in three ways: to appraise the appearance of the
lit space, to measure the daylight distribution and to examine the direct sunlight
penetration. For appearance appraisal it will be necessary to provide viewing
slots. These need to be placed at a normal head position and can be used under
real or artificial sky conditions. It is of course important that no stray light
enters the model through the viewing slot. It is often easier and more convenient
to use a camera.
When the model is to be used for measuring the daylight distribution,
usually under an overcast sky condition, it will be necessary to provide entry
positions for small photocells, but it must be possible to seal these openings
when the measurements are being made to avoid errors due to light leakage.
It is useful to measure not only the inside values but also an outside,
unobstructed, sky value, which will enable the measurements to be quoted in
terms of daylight factor. The measurements can be made under a real overcast
sky, but it is more convenient to use an artificial sky to overcome the problem
of light level variability.
Models can also be used to test sun penetration. In this case the model can
be used in conjunction with a spotlamp to represent the sun and a sundial to
enable the correct relationship between the model and the spotlight (artificial
sun) to be established. With this equipment a range of sun positions can be
explored. An alternative is to use the model in conjunction with a heliodon,
which enables the sun/site/building relationship to be explored more easily.
Lighting for particular applications
Fig. 4.17
37
Virtual daylight model
created in IES Virtual
Environment (images
courtesy of A Bissell, Cundell
LLP.)
Whilst few design practices have their own artificial sky or heliodon,
these pieces of equipment are commonly available in schools of architecture,
university building departments and research establishments.
Calculations for the determination of point daylight factor, illuminance
and luminance are described in the SLL Code for Lighting(8) (2009 edition) and
Lighting Guide LG10: Daylighting and window design(43), and therefore are not
included here.
38
Lighting Guide 5: Lighting for education
5
Lighting for
particular
applications
5.1
Classification
of teaching
and conference
spaces
5.2
General
performance
requirements
for learning
spaces
In the last decade a better understanding of learning and changes in teaching
methods, plus the increased demand for sustainable building design, has led to
some innovative educational buildings that provide stimulating and adaptable
places to learn for children and adults. Some school sites combine school and
community use with, for example, an ‘early years’ centre, enhanced sports
provision, a public library or health centre. Other recent design developments
include the use of innovative glazed facades incorporating sun shading.
Educational spaces need to be designed for present and future learning
and teaching styles and organisation; a difficult task given that a school may last
for over 40 years. But learning spaces should be suitable, safe and secure as well
as attractive and inclusive places in which to learn and work.
Lighting, both electric and natural, plays a key part in the performance of
all these buildings and research suggests that it plays a key part in the learning
rates of students. Some of the recent design ideas include: classroom shapes
other than rectangular; use of innovative facades including sun shading, glazing
and modern construction methods; combined buildings that are suitable for
pupils and public inside and outside of school hours (and that may incorporate
early years care); public library spaces; health centres, extending sports
community use and so on, in some cases creating multi-use ground floors with
more specialist restricted use upper floors.
Modern learning spaces need to have the flexibility to accommodate
different activities and teaching methods. This may be by rearranging furniture
or by merging spaces (e.g. for two or three classes to work together or for
community use after school hours). Some large spaces may be multi-functional,
each activity requiring different lighting (for example a space used for both
drama performances and exams). There may be large open-plan spaces where
more than one teaching activity, formal or informal, takes place at the same time.
Lighting, both electric and natural, plays a key part in making these spaces
function well; it can also benefit students and other users with a sensory
impairment. Lighting or lighting controls need to be functional in every
scenario.
As teaching experts advocate new methods of interactive learning,
perhaps with multi-disciplinary spaces catering for two or three classes and
many teaching staff, we may see so-called flexible learning and teaching spaces,
a wider range of spaces, more multi-use of spaces, increased community use (and
therefore a wider range of activities), increased inclusion (and therefore more
with students and users with sensory impairment). Lighting plays a key part in
making these spaces function well. Importantly these spaces recognise the
benefits teachers and students can gain in having staff close and from being able
to adapt the space for the best learning style and interaction. Each learning and
teaching method will create different lighting requirements for the space in
which they happen.
Table 5.1(44) indicates just some of the lighting measures required for learning
spaces. However the designer must not take these in isolation from the other
measures such as cylindrical illuminance (see section 3.7) and modelling index
(see section 3.8) and requirements for children with special educational needs
(SEN) (see section 5.17), and will need to consult actively members of the design
team dealing with thermal performance, ventilation and acoustics in particular.
The illuminance uniformity in the task area should not be less than the
minimum uniformity values provided in Table 5.2. The illuminance uniformity
in the immediate surrounding and in the background area should not be less
than 0.4.
Daylighting performance for educational buildings is given in Table 5.3.
Lighting for particular applications
39
Table 5.1 Lighting performance for educational premises (reproduced from BS EN 12464-1(31) Tables 5.29, 5.35 and 5.36 by permission of
the British Standards Institution)
Ref.
Type of interior, task or activity
Em (lx)
UGRL
Uo
Ra
Remarks
1 Nursery school, play school:
1.1
Play room
300
19
0.4
80
1.2
Nursery
300
19
0.4
80
1.3
Handicraft room
300
19
0.6
80
300
19
0.6
80
2 Educational buildings:
2.1
Classrooms, tutorial rooms
Lighting should be dimmable
General: maintained illuminances on the wall
should be 50% of the task area illuminance or
Ev = 100 lux, and on the ceiling should be a
minimum of 30% of the task illuminance or
Eh = 50 lux
2.2
Classroom for evening classes
and adults education
500
19
0.6
80
Lighting should be dimmable. The designer
should consider very carefully whether an
elevated illuminance of 500 lux will offer any
benefit or simply be misused when the space is
used to teach children
General: illuminances on the wall should be
50% of the task area illuminance or
Evmin = 100 lux and on the ceiling should be
30% of the task illuminance or Ehmin = 50 lux
2.3
Auditorium, lecture halls
500
19
0.6
80
Lighting should be dimmable to suit various
audio visual needs
2.4.
Blackboards (see remarks for
other colours)
500
19
0.7
80
White and green boards should require less
light due to higher reflectance, a luminance of
80–160 cd/m2 is recommended
Prevent veiling reflections
The teacher should be illuminated with suitable
vertical illuminance
Where used for projection the surface finish
should be carefully considered and lighting
should be dimmable
2.5
Demonstration table
500
19
0.7
80
2.6
Art rooms
500
19
0.6
80
2.7
Art rooms in art schools
750
19
0.7
90
2.8
Technical drawing rooms
750
16
0.7
80
2.9
Practical rooms and laboratories
500
19
0.6
80
2.10
Handicraft rooms
500
19
0.6
80
2.11
Teaching workshop
500
19
0.6
80
2.12
Music practice rooms
300
19
0.6
80
2.13
Information technology (IT) rooms
300
19
0.6
80
2.14
Language laboratory
300
19
0.6
80
2.15
Preparation rooms and workshops
500
22
0.6
80
2.16
Entrance halls
200
22
0.4
80
2.17
Circulation areas, corridors
100
25
0.4
80
2.18
Stairs
150
25
0.4
80
2.19
Student common rooms and
assembly halls
200
22
0.4
80
2.20
Staff room/office
300
19
0.6
80
2.21
Library: bookshelves
200
19
0.6
80
2.22
Library: reading areas
500
19
0.6
80
2.23
Stock rooms for teaching materials
100
25
0.4
80
In lecture halls 750 lx
Colour temperature ≥5000 K
For specific industry based teaching in further or
higher education additional advice may be
sought from Lighting Guide LG1: Lighting for
Industry(51)
Artificial and natural lighting should comply
with the guidance in Lighting Guide LG7: Office
lighting(39)
200 lux on the vertical face of the bookshelf
Table continues
40
Lighting Guide 5: Lighting for education
Table 5.1 Lighting performance for educational premises (continued)
Ref.
Type of interior, task or activity
Em (lx)
UGRL
Uo
Ra
Remarks
Sports lighting performance requirements are
detailed in BS EN 12193(32)
2 Educational buildings (continued):
2.24
Sports halls, gymnasiums,
swimming pools
2.25
School/college canteens
2.26
Kitchen
300
22
0.6
80
200
500
22
22
0.4
0.6
80
80
3 Conference and meeting rooms:
3.5
Conference and meeting rooms
500
19
0.6
80
These may be classed as high risk tasks for
emergency lighting
Lighting should be dimmable
Table 5.2 Relationship of illuminances of immediate surrounding and background areas
to task area (adapted from BS EN 12464-1(31) Table 1 by permission of the British Standards
Institution)
Illuminance on the
task area (lx)
Illuminance on immediate
surrounding areas (lx)
Illuminance on
background area (lx)
≥750
500
300
200
150
≤100
500
300
200
Etask
Etask
Etask
100
100
100
100
100
Etask
Table 5.3 Daylighting performance for educational premises
Ref
Type of interior
Daylight factor (%)
Average
Minimum point
1
Entrance, Reception
10%
4%
2
Atrium
5–10%
2–4%
3
5%
2%
4
Classrooms, including standard,
science, food preparation, craft
and art rooms
SEN classroom
5%
2%
5
Lecture theatres
2–4%
1%
6
Libraries
2–5%
1–2%
7
Sports halls
5%
2%
8
Dining hall
4–5%
1–2%
9
Offices and meeting rooms
5%
2%
Remarks
This area serves as a transition from the external
environment to the internal environment and
needs to provide a lighting level to allow the eye
to adapt. Glare for any permanent staff working
in this area must be considered.
Classrooms often look into the atria space and
as such borrow daylight from the space and use
the brightness of the space as part of the view.
Glare into classrooms needs to be considered
carefully as does privacy.
Daylight should be the predominant lighting
component for the majority of the day.
Due to the nature of SEN children the daylight
and view should be considered together, some
rooms with daylight and views and some rooms
with good daylight but more limited visual
stimulation will be required to suit the different
needs of the children.
Daylight keeps people alert and therefore it is
essential for all learning environments. However
in a lecture theatre the daylight must be able to
be eliminated to suit the presentation style and
projection equipment.
Delivering good levels of daylight between the
shelves is typically difficult; however the reading
areas should have good levels of daylight.
As sports halls are often used for exams then
providing good levels of daylight to keep the
students alert is essential. Control of the
daylight will be required for some sports.
Lighting for particular applications
5.3
Lecture
theatres and
lecture rooms
41
The choice between a lecture room (basically flat, see Figure 5.1) and a lecture
theatre (raked, see Figure 5.2) will be determined by the audience size. If it is
less than 60 there is little point in providing a raked room. If it is more than 80,
raked seating is essential, unless the lecturer is raised on a stage or podium.
Fig. 5.1
Flat seating arrangement using
hidden light sources indirectly
to audience, speaker and the
walls (photograph courtesy of
NDYLight)
Fig. 5.2
Raked seating arrangements
with differing approaches to
audience and presenter stage
area lighting; harsh downlight
is softened by vertical elements
to the side of the stage
(photograph NDYLight)
5.3.1
Lighting and visual
needs
The lighting in a lecture space must reveal the lecturer to the audience and the
audience to the lecturer, and also provide for the other visual tasks involved.
These include observing demonstrations, reading what is projected onto the
screen, or written on the whiteboard, and the taking of notes. Note-taking has to
continue when presentations, video or interactive presentations are used.
The lighting in a lecture theatre may conveniently be thought of in terms
of that for the audience area and that for the presentation area (see Figure 5.2)
though this distinction should not be pushed too far; in many lecture theatres,
especially smaller ones, the audience area lighting may well function as ambient
lighting and provide much of the illumination in the demonstration area as well.
5.3.2
Lecture theatres
These are rooms used for the delivery of formal lectures with raked floors and/or
balconies or galleries and with fixed seating.
5.3.2.1 Lighting the audience
For the audience area the basic choice is between incandescent, LED and
fluorescent lighting. Incandescent light is readily controllable in intensity and
direction, is often preferred on aesthetic grounds, and may have some benefits in
terms of reduced noise. However, even in its best form it is inefficient in terms
of energy usage and the heat that it introduces to the building has to be removed.
Modern fluorescent lamps, with good colour rendering, are very much more
energy efficient and offer considerable benefits in lamp life, and in those theatres
which are heavily used, e.g. in schools and colleges, maintenance and energy
economics will usually dictate their use.
LEDs offer the designer a further choice, though at the time of writing the
technology is just entering the mainstream. Issues of colour rendering, light
source life and efficacy are still inconsistent across the industry and the designer
would do well to consider these issues carefully before specifying LED
luminaires; further advice can be found in Guidelines for specification of LED
lighting products(45), issued in August 2009. That said, there appear to be many
manufacturers offering good quality luminaires containing efficient LED sources
and this technology may offer a long life and fully controllable solution for many
lecture theatres, especially where access may be difficult.
Other types of discharge lamp, such as high pressure sodium, are not
suitable due to poor colour rendering, run-up and re-strike times, and flicker.
42
Lighting Guide 5: Lighting for education
Metal halide sources may offer some benefits when dimming technology is fully
developed, but at present still cause problems with re-strike times and lamp life.
Whatever type of lighting is used, the luminaires must be positioned so
as not to create glare problems either for the audience or the speaker, as shown
in Figure 5.3. This means that, unless the ceiling is exceptionally high, the
luminaires must be mounted on, or recessed into the ceiling. Figure 5.4 shows
that when the ceiling is not a flat horizontal surface, it may be possible to make
use of its shape to conceal the luminaires from the direct sight line of the
audience provided that they do not become bad glare sources for the lecturer.
The UGR at any point of the audience area should not exceed 19.
Fig. 5.3
Luminaires at positions
such as A and B are close
to eye level for back row
students and may cause
significant discomfort
glare
Fig. 5.4
Luminaires hidden behind
elements of the structure
or acoustic treatment will
cause less glare to
students but may still be a
problem to the lecturer
A
B
When incandescent, LED or compact discharge/fluorescent lighting is
used, high direct ratio luminaires with a tight beam angle should be avoided.
Although these are often used in theatres and concert halls, they produce poor
modelling of peoples’ faces, with the result that the lecturer cannot clearly see or
interpret the reactions of the audience. When surface mounted luminaires are
used, they should not produce a harsh distracting halo on the ceiling around
them that may itself become a glare source. Care should also be taken with
luminaires mounted close to the walls to avoid high luminance on the wall,
which can also be distracting.
When fluorescent lighting is used, ceiling mounted luminaires of the
recessed or semi-recessed type may be used. The latter are preferred to prevent
the ceiling appearing too dark. In order to avoid note-taking shadows, the
luminaires should be mounted with their long axis parallel to the rows of seats
(see Figure 5.5), though it is not usually practicable to correlate the rows of
luminaires with the rows of seats beneath. The average illuminance on the
working plane (usually 0.85 m above the floor) should be 500 lux, but should also
be controllable to suit the needs of the audience. Bare fluorescent tubes should
not be used if they are visible either to the audience or lecturer.
If the ceiling is white or of a light colour and is of uncluttered design, pure
indirect lighting may be used for the audience area, but the energy costs will be
higher. This method produces illumination that is quite free of glare, but is felt
by some to produce a soporific effect. In practice the light sources usually have
to be concealed in the cornices. Traditional uplighters may cause obstruction to
some of the sight lines and psychologically provide a barrier between the lecturer
and some parts of the audience and perhaps are best avoided.
Lighting for particular applications
Fig. 5.5
43
Luminaires orientated
with their long axis
parallel to the seating
with separate lighting
oriented perpendicular to
the boards to light the
demonstration area and
speaker (photograph
courtesy of Thorn Lighting)
Lamps used should be of colour rendering greater than Ra = 80. The
common ‘white’ and ‘warm white’ fluorescent tubes do not meet this requirement and under the provisions of the Energy-using Products Directive will be
withdrawn from sale in coming years. An efficient solution is offered by
triphosphor T26 or T16 fluorescent lamps.
5.3.2.2 Lighting the
demonstration area
In small lecture theatres and any theatres that have an unbroken horizontal
ceiling, it is a good plan to carry the general lighting forward to serve the whole
area and to add additional lighting as described below. This technique does not
emphasise any division between the demonstration and audience areas. In very
large lecture theatres (see Figure 5.5), and especially those where the ceiling
height is reduced at the front, it is advisable to use quite separate lighting
systems for the demonstration and audience areas. The demonstration area
lighting needs to be carefully directionally controlled.
In small lecture theatres luminaires designed for display use should be
used. In larger theatres luminaires designed for stage lighting may be more
appropriate. The lamps or luminaires should preferably be concealed from the
view of the audience. They may otherwise become very obtrusive and give the
room a theatrical look.
The position and angling of luminaires in the demonstration area is
critical. The best alignment for ceiling mounted luminaires is about 45° to the
vertical, and between 30° and 45° to the side. If the angle is near the vertical it
may produce grotesque shadows on the lecturer’s face, and if it is near the
horizontal the lecturer may be dazzled when attempting to address the audience.
Similar considerations apply to luminaires mounted on the side walls.
Illuminance at table-top height in the demonstration area should be higher, but
not more than double those of the audience area. The recommended values are
500–750 lux for the demonstration area and 300–500 lux for the audience area.
Lighting provided specifically for the lecturer to read notes while the
theatre is darkened for the purpose of computer projection needs careful
attention. The problems are that light direct from the source, or light reflected
from the notes and desk, may fall on the screen and spoil the appearance of the
projection; it takes very little stray light to affect the projected image. The best
solution is to incorporate carefully shielded low power light sources in the
lectern itself. The illuminance of the notes should be kept as low as possible,
5–15 lux is sufficient.
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Lighting Guide 5: Lighting for education
In most modern lecture theatres the speaker will primarily use a screen or
laptop computer, which is self-lit. In these cases the lectern is almost always
without an in-built light, or it may be desirable to switch off the lectern lighting
altogether. However, to enable all members of the audience to see the lecturer
clearly and be able to discern body language and facial expression, including
importantly lip reading for those with hearing impediment, there should be
sufficient light on the speaker. This can be achieved either with theatre lighting
positioned specifically for the task or by additional linear fluorescent lamps or
LEDs simply controlled with a dimmer and mounted within the lectern itself.
5.3.2.3 Sight lines
Fig. 5.6
The first requirements of a lecture space are that the audience shall see the
lecturer easily and that the lecturer shall see the audience easily. Lecture
theatres should not be raked too steeply, see Figure 5.6, as this makes the
audience feel uncomfortable and can present problems with image projection.
The seating layout is important in raked theatres; if straight rows are used the
seats at the ends of the front rows offer a very oblique view.
Steeply raked lecture
theatres can cause
problems with projection
and make the audience
feel uncomfortable
There can be little social contact between different members of the
audience, and this is disadvantageous from two points of view: (a) it discourages
audience participation and (b) it does not facilitate or encourage discussion and
questions after a lecture.
For these reasons, the curved rows in Figure 5.7 are to be preferred using
a fan shaped plan. This arrangement has the disadvantage that if the room is only
two-thirds filled all the audience may be in the back half. Figure 5.8 shows a
good design compromise with at least half the length of the side walls parallel so
as to limit the length of rows at the back. It is most important in any lecture
theatre that there is an adequate space in the demonstration area. In practical
terms, this means that there should be at least 3 m between the front wall and the
feet of people sitting in the front row.
This not only allows an adequate area for demonstration purposes and
improves the sight lines, but it gives the theatre a spacious quality, see Figure 5.9.
If the front wall is too close to the seats the theatre will look cramped, and have
a claustrophobic atmosphere.
Demonstration
area
Demonstration area
Fig. 5.7
Fan shaped lecture theatre
Fig. 5.8
Modified fan shape with more
practical straight rows
Lighting for particular applications
Fig. 5.9
Layout of the theatre
creates a feeling of space
(photograph courtesy of
NDYLight)
5.3.3
Lecture rooms
Lecture
area
Fig. 5.10
‘X’ marks possible
positions for spotlights in
a small lecture room on
ceiling or side walls
5.3.3.1 Lines of sight and glare
Fig. 5.11
A good lecture room
layout
45
These are rooms used mainly for the delivery of formal lectures, generally with
level floors and often with fixed seating. This category includes rooms with a
raised step or podium for the lecturer, and rooms with one or two raised steps
towards the rear of the seating.
Because of the smaller dimensions, the audience area lighting in lecture
rooms will usually serve the demonstration area as well. It is desirable that the
lecturer and the immediate surroundings are a little brighter than the rest of the
room and this can usually be effected by the use of a few spot type luminaires
directed towards the lecturer. However they must be carefully positioned so as
to avoid glare to the lecturer. Usually this will mean that they have to be
mounted either on the side walls, or on the ceiling adjacent to the side walls; the
positions are shown in Figure 5.10
If a fixed lecture bench is installed luminaires should not be mounted
directly over it for demonstration purposes. In this position they may cause
specular reflections from demonstration equipment which makes it very
difficult to see what is going on. Lighting from the side is equally effective and
spotlights may be mounted in the same position as those to light the lecturer.
The general lighting should be arranged to produce an illuminance above
500 lux at desk level in the audience area. It should be reasonably uniform and
if fixed seats are installed right up to the walls the illuminance at desk level at
the wall should not be below 70% of the average illuminance. If there is an aisle
next to the wall this does not apply. The lamps used should be of better than
Ra = 80. In order that members of the audience may take notes whilst projected
images are shown, a much lower level of general illuminance in the range of
15–30 lux is needed, achieved by dimming.
Lecture rooms are usually rectangular in plan and experience shows that the
best seating plan is that with the lecturing area at one end of the room with rows
of seating parallel to the short dimension as shown in Figure 5.11.
Figures 5.12 to 5.14 show sightlines for typical layouts of lecture rooms.
In the case of a lecture room that is basically flat the sight lines may be greatly
improved by raising the rear half of the audience on one or two steps and raising
the lecturer on a step. Lecture rooms in general have a much lower ceiling than
lecture theatres, and in the absence of raked seating the sightlines become
critical. The lighting equipment should be arranged so that the luminaires do
not cause serious glare to the occupants of the rear row of seats, as shown in
Figure 5.15, or to the lecturer as shown in Figure 5.16. When fluorescent
lighting is used the luminaires should be of the recessed or semi-recessed types;
if this is not possible they may be provided with the glare shields illustrated in
Figure 5.16. It may sometimes be possible to use ceiling ribs as glare shields. On
no account should bare fluorescent tubes be visible to the audience.
The UGR at any seat should be less than 19. It should also be remembered
that avoiding glare for the audience may create glare for the lecturer; in
particular, the lecturer must not be subjected to disability glare.
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Lighting Guide 5: Lighting for education
Fig. 5.12
Sight lines in a lecture
theatre with a flat floor
Fig. 5.13
Sight lines may be
improved by raising the
lecturer on a step
Fig. 5.14
Sight lines can be
improved further by
raising the rear seats
Fig. 5.15
Back row glare in a
lecture room; luminaires
at A and B are very close
to the students’ sight
lines, and will cause
intolerable glare
Fig. 5.16
Glare shields or louvres
will overcome the
problem of back row
glare
5.3.3.2 Provision of daylight
A
B
Cut off
angle
Almost all presentations will require controlled lighting. For that reason, lecture
theatres and rooms are often built with little or no access to daylight. Equally,
people do not like to feel shut in, especially when lectures are given during
daylight hours, and there are many who have a preference for working under
natural light. In rooms the size of lecture theatres, the provision of natural light
in sufficient quantities for working purposes requires very large areas of glazing.
This is not only expensive from the point of view of heat loss, but makes it
difficult to achieve a good blackout. Furthermore, unless the windows are north
facing, or sufficiently shaded externally, there may be severe problems with solar
heat gain in summer.
Lighting for particular applications
47
The only way in which an adequate blackout can be achieved in such
rooms is by the use of completely opaque blinds, running in grooves at the sides
to provide a light trap. Curtains or venetian blinds are not adequate. Blinds
should be of light colour on the inside, so as not to present a large black area
when down, and should be motor operated due to the area of window involved
and the need for frequent opening and closing. Blinds should also be of a light
colour on the outside, to prevent excessive solar heat gain.
It may be desirable to provide occupants a view of the outside world in
order to provide some visual escape rather than to provide lighting. The lecture
theatre shown in Figure 5.5 illustrates that very much smaller areas of window
can be used, and the problems associated with them are consequently much
reduced. However, the need for a perfect blackout remains and groove-enclosed
blinds are needed, though in such cases they may be hand-operated.
Windows should not be provided in either the front wall or back wall of
a lecture theatre or lecture room. The former would produce intolerable glare to
the audience and the latter would cause serious veiling reflections on the board.
Skylights should be provided with care; they require elaborate blackout
arrangements and are very difficult to keep clean.
From the point of view of presentation, it may be better for lecture
theatres and rooms to be windowless as this provides less problem controlling
glare from sunlight. Since the occupants rarely have to remain in them for more
than an hour without a break, problems of claustrophobia do not arise, although
they may well do so in small teaching rooms. Many institutions have made
extensive use of windowless lecture rooms with considerable success. However
windowless lecture theatres and rooms require forced ventilation that may lead
to noise problems, but it should be noted that large theatres with extensive
glazing also require forced ventilation. It is preferable, however, that all teaching
spaces should allow daylight so the user can retain a link to the time of day and
weather. A lack of daylight may adversely affect occupants’ circadian rhythms
and hormone production (though further research is needed), as well as increase
the electrical load in the space due to electric lighting being used when daylight
could be utilised. As with skylights careful and complete blackout blinds should
be provided if daylight is permitted.
Light traps (e.g. two sets of doors or other effective means for excluding
daylight) should be provided in all lecture theatres and rooms to prevent
unwanted light getting in when the theatre is darkened for presentation. This is
particularly so in the case of entrances at the rear of the theatre, which when
opened suddenly by a latecomer may allow full daylight to fall on the projection
screen. These light traps should also function as sound traps.
Such doors should not be provided with windows, unless essential for fire
safety, if it is not possible to provide proper light traps. If automatic door closers
are installed they should be of a design that allows the door to be closed quickly
and silently.
5.3.3.3 What the audience
sees
The audience should be able to concentrate on the lecturer, screen or board, and
the decoration, furnishings and equipment should not be competing with the
lecturer for attention. The lecturer’s desk, board and screen must be so placed
that they do not obstruct the view of the audience. If a computer projector is
used, great care must be taken to see that it does not obstruct either the
audience’s view of the lecturer or the lecturer’s view of the audience. Care
should be taken to avoid intense glare to the lecturer from projectors that may
lead to eye complaints later in life.
Specular reflections of light sources and windows on the board, sounding
boards and glazed portraits should be avoided. Also avoid backgrounds with
disturbing patterns, and backgrounds full of fussy details. The audience’s view
of the front of the lecture room or lecture theatre should be clear and free from
visual clutter; in particular the front wall should be kept clear of pipework,
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Lighting Guide 5: Lighting for education
conduits, and ventilation trunking. In some cases the luminaires themselves
may provide visual clutter and should be carefully chosen and positioned.
5.3.3.4 Decoration and
furnishings
It is the decoration and furnishings within a lecture theatre or room which, in
combination with the lighting determine its appearance and contribute to that
indefinable quality that is usually called ‘atmosphere’ or ‘character’.
The choice of colours and finishes should be made at an early stage in
conjunction with other decorative finishes and furniture. The use of darker
colours on the side walls of theatres will help concentration. The surfaces of the
side walls should have some degree of texture, such as that provided by timber
panelling, textile covered panels, slightly textured plastics or recessed-pointing
brickwork.
Shuttered concrete is not recommended as it soon gets dirty and is not
easy to clean. In a lecture room without fixed seating it may not be desirable to
treat the side walls as a feature, but darker-toned colour can be used behind the
lecturer. Ceilings should be white. Care should be taken to provide some light
either directly or indirectly onto the ceiling. Walls should be of a different
colour from the ceiling in order to define the boundaries of the interior space
and avoid a feeling of claustrophobia.
Matt or semi-matt surfaces are desirable as high gloss areas will cause
specular reflection and be distracting.
Colour contrasts of a modest nature are desirable since a bland interior
scheme, combined with dim lighting, tends to cause drowsiness amongst the
audience. These contrasts can usually be obtained by careful choice of the
colours of the seating as this presents a large area of colour; mid-toned colours
are best in a definite but not too strong hue. The flooring colour does not
contribute a great deal to the scheme in a lecture theatre. Whether carpet or hard
finish a neutral colour is the most practical choice.
5.3.3.5 Switches, dimmers and
controls
In any lecture space the lighting controls need to be as simple and
comprehensible as possible — lecturers should be more concerned with their
subject matter than light switches. In the main, the only lighting settings
needed in a lecture theatre are:
(a)
full lighting, to about 500 lux, for adult use
(b)
reduced lighting, to be considered the primary setting, to about
300 lux for child and young adult use
(c)
audience area lighting reduced to a low level and demonstration
area lighting off for the purpose of image/video projection, but
allowing enough light for the audience to take notes
(d)
all lighting off for the projection of specific content, and for the
purposes of visual demonstrations.
Abrupt changes in the lighting are disturbing to the audience, and
lighting controls should enable gradual changes to be made in preference to
plain switches. A good system is that in which the only controls are four
pushbuttons, corresponding to the states above. On pushing the appropriate
buttons the lighting assumes the appropriate scene. In such installations the
time taken to go from full-on (a) to full-off (d) should not be too long; about four
seconds is sufficient. A lighting scene selection panel should be situated
conveniently for the lecturer and any support staff, with some form of override
at each entrance, suited to entry and exit from the space. Whilst it may be
attractive to include absence detection to ensure lighting is switched off when
the theatre is empty, the design should take care to ensure any sensor used
covers the space sufficiently and with a suitable level of sensitivity.
All lecture theatres should be arranged for one-person operation, as
circumstances inevitably arise where a lecturer has to speak without the services
of an attendant.
Lighting for particular applications
49
5.3.3.6 Audio-visual
considerations
As most modern lecture spaces use computer based projection, the theatre
should be laid out with sufficient consideration for the use of the projector and
accompanying laptop computer. Inadvertent spill light onto the screen should
be avoided especially where older, less powerful projectors are in use. Similarly
the lecturer should have sufficient illuminance onto the computer to enable
keyboard detail to be discerned and to ensure that minimal adaption change is
required between the view of the audience and the screen in all scenes.
5.3.3.7 Access and movement
Access doors should not be in the front wall of the lecture theatre or room,
where they add to the visual clutter, and distract attention. The same applies to
the doors of preparations rooms, lecturers’ rooms and stores.
All lecture theatres and lecture rooms sooner or later become used for
purposes other than that to which they were originally dedicated. Consequently
all items in the demonstration area should be movable and removable. Hence
the lighting and control of the lighting to these spaces should be easy to re-aim
or re-commission.
Experience shows that when demonstrations are mounted, services other
than electricity are rarely, if ever, called for and there is little point in installing
a fixed bench simply to provide terminal points for water, gas, and other outlets.
If such services are needed, they are much better installed in wall cupboards
where they can be kept both locked and out of sight until they are wanted.
When members of the public may be present, all exits to a lecture
theatre/room be marked with permanently illuminated exit signs, and all exit
routes must have sufficient emergency lighting. Light from such signs falling on
a projection screen can ruin the effect of presentations or demonstrations, they
should therefore be aligned so as to be visible to the audience, but not to throw
light onto the projection screen.
Additional lighting at low level may also be beneficial to aid access and
egress during presentations. The glare from such luminaires must be carefully
controlled to avoid presenting problems to the lecturer.
5.3.3.8 Use for theatrical
presentations
Possibly because they resemble legitimate theatres in shape, and because they
often constitute the largest auditorium in a particular institution, lecture
theatres are sometimes chosen as the venue for theatrical presentations.
Such presentations can be greatly helped by the provision of further
special facilities for lighting such as theatre lighting supports and controls. The
following paragraphs describe the additional provisions that should be made if
the room is to be easily adaptable for these purposes. It is stressed that these are
additional, and it is necessary that the requirements of the previous sections are
met first.
When such rooms are used for theatrical purposes, they will almost
certainly be subject to additional legislation such as additional requirements for
emergency lighting; the designer should consult local authorities on such
matters. Relevant publications and general advice are available from the
Association of British Theatre Technicians (www.abtt.org.uk), and detailed
advice and planning from members of the Society of Theatre Consultants
(www.theatreconsultant.co.uk).
The additional provisions needed in the audience area are:
—
The lighting must be dimmable smoothly and without flicker to
1% of its maximum level.
—
Exit signs as required by BS EN 5266(46). Luminance and spill
light should be restricted to avoid glare and interference with
stage lighting effects.
—
Light and sound traps on all entrance doors (or at least those
used by latecomers and for access to toilets). Lighting within a
light trap should be primarily from the dimmed house lighting
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Lighting Guide 5: Lighting for education
system, but a low power light from the external system may also
be needed, and a maintained emergency light.
—
Provision for theatrical lighting installation using professional
spotlights rigged on standard 48 mm diameter scaffold tube and
connected using industry standard theatre plugs and sockets.
Essential locations are above the seating parallel to the front
curtain at approximately 45° elevation from 1.8 m above the
front of the stage. Steeper and shallower positions will also be
useful as will positions on the side walls at 45° in plan to centre
stage. Safe access for adjustment and relamping must be
anticipated. Each socket should be wired suitably for the chosen
power and dimming control systems.
Additional provisions needed in the stage area:
—
At least 2 m wing space either side of the stage
—
Adequate headroom to allow overhead stage lighting to be
hidden from sight, i.e. at least 1 m from the upper sightline
—
Access to both sides of the stage, not through the auditorium,
with sound and light traps and silent closing doors
—
Access to dressing rooms
—
Access to the auditorium, not via the stage
—
Access for scenery from delivery vans
—
Provision for front curtain with winch mechanism
—
Provision for side and rear masking curtains to hide performers
awaiting entrance
—
Over-stage rigging for hanging scenery and top masking. This
can be basic exposed rolled steel joists (RSJs) and scaffold pipes,
with manual or motorised winches, or fully counterweighted
flying systems requiring two to three times the visible stage
height.
—
Work-lights at both sides, rear and over main stage for setting
and changing scenery with local switching and master switch at
stage manager position. Fluorescent battens with protective
trough reflectors and wire guards are usually used for worklights. Instant operation is essential. Dim, shielded lights are
also required for used during performance but these can be
rigged as required if full theatrical standards are not specified.
—
Provision for theatrical lighting installation using professional
spotlights rigged on standard 48 mm diameter scaffold tube and
connected using theatre lighting industry standard plugs and
sockets. Essential locations are above the stage parallel to the
front curtain immediately behind the curtain line, 1 m in front
of rear wall and between at 1 m to 1.5 m intervals. Each socket
should be wired suitably for the chosen power and dimming
control systems.
Control of the lighting and sound systems may be effected from the
projection room or separate lighting and sound control rooms. The lighting in
those rooms should be similar to that for a projection room and the rooms
should be sound-proofed. A good view of the stage is essential in each case.
Loudspeaker reproduction of platform sound is essential, and if a headset
communication system is used appropriate wiring should be provided.
All systems should be arranged so that they can be operated by a single
person if necessary. The control rooms should be of sufficient size to cater for
dimmer circuits that may be involved. The sound control room should have
connections to tie-lines for microphones and loudspeakers both on stage and in
Lighting for particular applications
51
the audience area, and also be connected to the headset communication system,
the dressing room sound system and the audience hearing aid induction loop
system if one is installed.
5.4
Teaching
rooms
These are rooms used mainly for class teaching purposes, with flat floors and little
fixed furniture except, possibly, cupboards, whiteboards and projection screens.
Such rooms will usually have a seating capacity of around 30, but may extend in
modern educational buildings for multiple classes with up to 90 occupants.
5.4.1
Lighting and visual
needs
Lighting for students with sight problems need careful design and suitable aids
to reading will need to be considered. Bear in mind that for some impairments
higher illuminance, in itself, may not be the solution. More detail is given in
section 5.17.
5.4.2
Rooms intended for
presentation
The designer should still consider the phrase ‘Light the teacher, light the board,
light the desk’ but must above all light the face, at whatever height and whatever
location in the class. Teaching is a mobile interactive activity even in classrooms
designed around formal instruction, and the student should be able to clearly
see the teacher’s face, and vice versa, from any position. Well applied measures
such as modelling index (section 3.8) and mean cylindrical illuminance (section
3.7) as well as more traditional horizontal task illuminance should be considered
throughout the class and at appropriate facial heights.
5.4.3
Rooms intended for
interactive learning
In learning spaces where there is intended to be a high proportion of use of
interactive whiteboards or display screens with touch sensitive surfaces, the
designer needs to consider carefully the capabilities of this equipment. Where it
is unclear what quality of equipment is to be provided, the designer should
assume that equipment will be relatively new and capable of good performance.
This is acceptable due to the high rate of change in the technology available for
display screens and the slower rate of update of lighting in most buildings.
In cases of fully interactive whiteboards, where lit by close offset front
projection, it is likely that the screen can cope with significant luminance and
lighting, except perhaps display spotlights, should not be considered a concern.
For self-lit interactive displays such as plasma or LCD monitors with a touch
sensitive front surface, the designer may have to consider limiting the luminaire
or daylight luminance to as low as 200 cd/m2. In most cases, based on the use for
self-lit screens, the designer should apply luminance limits from BS EN ISO
9241-307(47). Generally, as interactive screens will use positive polarity software,
the application of Case A, see section 5.10.1 (Table 5.4), is sensible.
Where possible, the specifiers of projection equipment should consider
the health and well-being of the presenter or teacher as the glare from poorly
placed projectors can cause considerable discomfort, and perhaps long-term eye
problems to those using them. Certainly the projector can affect the presenter’s
ability to interact with an audience and the layout of any teaching space should
give a lecturer room to present without standing in the way of the screen.
5.4.4
Rooms used for
practical work
These are rooms used regularly for class teaching purposes, without large
permanent pieces of apparatus set up. Such rooms will usually have a seating
capacity of about 30. This category will include many teaching laboratories.
5.5
Large
conference
rooms
These are rooms used mainly for conferences and meetings at which people may
address the audience from almost any point in the room. Such rooms will
usually have a capacity of about 60–120.
5.5.1
Basic lighting and
visual needs
The basic visual needs in a large conference room are that all members of the
audience can see the chairman and central officers clearly, and that all persons
present should be able to see each other reasonably well in order that a proper
dialogue may take place. Many presentations in conference rooms, e.g. the
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Lighting Guide 5: Lighting for education
reading of scientific papers, are essentially formal lectures, and the lighting
needs are similar to those of lecture theatres. However conference rooms are also
often used as cinemas or theatres and the lighting must be capable of meeting
those purposes also. Specifically the lighting must provide adequate
illumination for reading or taking notes at any point, good but not excessive
modelling and good colour rendering.
It must also be flexible and controllable from a single point, must be
absolutely silent and produce no thermal discomfort. Careful co-ordination of
the lighting design with the interior decoration and with the heating and
ventilating system is essential. Absolute blackout facilities will be needed.
Large conference rooms have a good deal in common with large lecture
theatres, and much of the information in the previous section applies.
Conference rooms usually have a clearly defined presentation area,
corresponding to the demonstration area of a lecture theatre, and a clearly
defined audience area. But the activities in a conference room differ from those
in a lecture theatre in these ways:
(a)
The audience may be present for long periods, often on several
successive days.
(b)
The proceedings although of a formal nature involve interaction
between members of the audience and they must be able to see
each other clearly.
(c)
Conference participants must be able to move easily between the
demonstration area and the audience area.
(d)
Simultaneous interpretation facilities may be required.
Item (a) above requires that participants should be able to move in and
out of the room whilst proceedings are in progress with the minimum of
disturbance and the seating should be arranged accordingly, with a greater ratio
of gangway space to seating space than is the case in lecture theatres. It is
important that participants can both get in and out without disturbing the
projector beam if one is in use.
In the UK it has always been the custom that those who contribute to a
discussion should do so from their seats, but in many countries this is not so. A
person wishing to speak must seek the chairman’s approval and then get up from
his seat and go to a central podium to speak.
The points made in the previous sections relating to the layout of the
seating apply equally here.
5.5.2
Lighting systems
and controls
The lighting requirements of the demonstration area of a large conference room
will be similar to those of a lecture theatre and all luminaires should be
controllable. Large conference rooms may be used for theatrical performances
or entertainment, consequently provision should be made for easily rigging
additional lighting equipment. The particular requirement is that appropriate
wiring be provided in the form of numerous circuits terminating in socket
outlets at the points where additional spotlights are likely to be wanted. These
circuits may be controlled from a stage lighting control system operated local to
the stage, or from the rear of the room. If it is known that a large conference
room will be used for theatrical presentations further special facilities may be
advisable. These are described in section 10.3.
The lighting of the audience area and the appearance of the whole are
crucial in a conference room. The audience must not only be able to see each
other clearly, but should not appear grotesque. For that reason downlighters are
not recommended as they produce shadows under the eyes, nose and chin which
are unacceptable, see Figure 3.7(a). If the ceiling is plain white, then recessed or
cornice lighting may be used, provided that there is sufficient direct lighting in
the demonstration area to provide a modest degree of ‘sparkle’. If this is not the
case, it is worthwhile introducing a few small luminaires for this purpose. The
Lighting for particular applications
53
furnishing and decoration should not be too dark, as light reflected from the
floor and furniture will significantly improve the modelling of participants'
faces. The points made about visual clutter in section 5.3.3.3 apply equally to
conference rooms.
5.5.3
Simultaneous
interpretation
booths
Strict specifications are laid down for the lighting of interpretation booths, see
ISO 2603(48). Care must be taken that light from them does not cause a nuisance
to the audience or speaker, glare or spill onto the projection screen.
5.6
Committee
and meetings
rooms
These are rooms used for meetings capable of seating up to roughly 30 persons.
5.6.1
Visual and lighting
needs
The basic functions of the lighting, be it daylight or electric are:
—
to enable the committee members to see each other clearly and
without glare
—
to enable members to read their papers and make notes
—
to enable committee members to see wall mounted displays.
It should be remembered that committees sometimes have to work under some
stress, especially when unpleasant or unpopular decisions have to be made. The
luminaires should be unobtrusive, and glare kept to a minimum.
5.6.2
Daylight
Committee rooms should always have some natural lighting; windowless rooms
are unacceptable for committee purposes. The essential problem of natural
lighting in a side-lit committee room lies in the fact that occupants on different
sides of a table are likely to be exposed to different forms of inconvenience.
Those facing a window may suffer glare, and see their colleagues opposite with
features in shadow silhouetted against a bright sky. Those with their backs to a
window may cast a shadow on their own papers. One possible approach is to
ensure that the chairman faces the window and can control both the blinds and
the electric lighting. This arrangement ensures that the chairman’s face is
clearly revealed, that there is no visual discomfort, and that the faces of other
participants can be seen comfortably. If this can be achieved, it is unlikely that
others will have difficulty in seeing one or another.
Whiteboards and flipcharts should not be placed next to a window since
disability glare will make them harder to read, even when discomfort glare is
acceptable. They should also not be placed where they may reflect an image of
the window. The prescription above, with the chairman facing the window, also
deals with these problems. Daylight quantity may need to be strictly limited for
computer-projected presentations and video conferencing. In the case of the
latter the designer must consider carefully the camera position(s), the modelling
of the facial features and the contrast between face and background in both
colour and luminance terms
5.6.3
Electric lighting
The geometry of lighting should correspond to the geometry of the conference
table, defining it as the focus of activity within the room. This does not
necessarily mean that the table should be the brightest surface; downlights are
particularly unsuitable as they cast harsh shadows, generate shiny reflections in
a polished table-top and tend to leave walls and ceilings in relative darkness.
The illuminance on the table should be about 500 lux, and the UGR at any point
of the room should be below 19.
The light distribution should produce a modelling index within the
limits recommended in the BS EN 12464-1(44), with suitable cylindrical
illuminance at all positions around the meeting table and presentation space.
Supplementary display lighting will be required for wall-mounted displays etc.
This is governed by the same geometrical constraints as whiteboard lighting.
The display lighting should be dimmable. Careful design of a committee room
54
Lighting Guide 5: Lighting for education
will remove the need for portable projection screens, and for ad-hoc
arrangements of computer projectors and blackout facilities.
5.6.4
Surface finishes
The background luminance should ideally be slightly lower than the luminance
of the occupants’ faces. A few small pictures or ornaments can do much to
improve a committee room, but large and complicated features may distract the
attention or affect the exposure of video conference equipment and should be
avoided.
5.7
Multi-purpose
rooms
These are rooms used for a wide variety of purposes, such as school halls, some
sports halls, assembly rooms, function rooms, community and church halls.
5.7.1
Lighting needs
The lighting designer should be involved with the architect and interior
designer from the start of the planning process. In attempting to design a
suitable installation for a multi-purpose room the first requirement is for the
designer, in consultation with the client, to draw-up a list of the purposes
envisaged for the room and an order of priorities of use. The prime lighting
needs in terms of illuminance and the controls needed for each separate activity
can thus be tabulated and if any common patterns exist they will be evident;
thus the lighting can be designed accordingly. However, in many cases no
common pattern will emerge and the designer will have to produce a
compromise design.
Fig. 5.17
Ambient lighting provides
for the needs of access,
maintenance and some
teaching with projector
and screen and also with
stage lighting for music
recital, drama and
theatrical shows
(photograph courtesy of
Thorn Lighting)
There are a few basic points, discussed below, that should be considered
at the start of the design process. These are the exclusion of daylight, the stage
lighting, and accommodating large chandeliers or other lighting supports. The
next requirement is for the lighting designer to determine what maximum value
of illuminance is required and for how long. This will determine the nature of
the main light sources. The designer may also have to consider whether a direct
or indirect lighting system is used.
Daylight may sometimes be excluded depending on the function of the
space. If the multi-purpose room requires lighting that is flexible and
controllable to a high degree then daylight may need to be excluded completely.
However, given the imperative to utilise minimal energy in lighting all spaces, if
windows, roof lights or skylights are to be provided they should be fitted with
light-tight blackout blinds of the type described for lecture theatres in section
5.3.3.2. This is particularly so in the case of skylights.
If the room has a definable stage area, then the lighting for it should be
regarded as stage lighting and designed accordingly. This may include the need
for ambient lighting to enable set building and general set-up or cleaning of the
stage.
Lighting for particular applications
Fig. 5.18
55
Sports halls are often
design for a multitude of
different activities; this
may include regimented
desk layouts during
examination time
(photograph courtesy of
Thorn Lighting)
If large luminaires such as chandeliers are to be used, they should be
positioned carefully as they can very easily obstruct both sightlines and the
beams of spotlights. Dimming is essential to provide sufficient flexibility in the
lit scene.
In the case of rooms whose primary use is for sports (see Figure 5.18) the
designer may need to consider over-lighting the space for other activities, such
as examinations, along with the associated limitations to uniformity, cylindrical
illuminance and modelling posed by these different requirements.
5.7.2
General lighting
Fig. 5.19
Flexibility in open plan
allows the space to be
used for any number of
tasks; the lighting and
controls needs to account
for all of these needs and
so may be a compromise,
in this case perhaps glare.
(photograph courtesy of
Thorn Lighting)
The function of the general lighting in a multi-purpose room is to provide an
overall uniform illuminance of acceptable colour rendering that is free from
glare, and which may be dimmed. The designer should research and indicate the
illuminance needed at working plane height, e.g. 0.85 m above the floor for desk
based tasks or floor level for some sports. If no such survey can be made the
designer should aim for a value of about 150 lux. If it is known that the room
will be used regularly for examinations then the provision should be for 500 lux.
The colour rendering should be of R ≥ 80.
56
Lighting Guide 5: Lighting for education
With the variety of activities that may take place, sightlines may be
anywhere, and it is important to avoid glare. This point is very well met if the
general lighting is indirect. If a direct system is to be used the luminaires should
preferably be fully recessed. If surface mounted fittings are used they should
have opaque or diffusing side surfaces, and in no circumstances should bare
lamps be visible. Suspended luminaires should not be used to provide general
lighting unless they are suited to the worst case use such as ball sports. Care
should be taken in avoiding glare not to overdo it; recessed downlighters in
particular give no glare at all but produce both a modelling effect on faces, which
is the reverse of what is wanted for a social occasion, and a gloomy atmosphere.
The illuminance produced by the general lighting should have a uniformity
ratio of a least 0.6 at working plane height, and this may be difficult to achieve
with downlighters if the ceiling is low.
5.7.3
Suitable light
sources
The main lighting will almost certainly be fluorescent. In a few cases high
pressure metal halide may be used where less control over illuminance is
required.
Fluorescent lighting may readily be dimmed but, by the nature of the
source, is less flexible. The term fluorescent lighting includes compact source
fluorescent lamps that can be used in relatively small luminaires. Fluorescent
lamps can be used to advantage in an indirect lighting system, especially where
the tubes can be concealed in cornices, coves, or in the structure of a ribbed
ceiling.
High pressure metal halide lighting has a relatively long warm-up time
and is thus of restricted value in multi-purpose rooms. However, for some
functions, e.g. exhibitions, it may be useful, especially if used to provide indirect
lighting.
If used for direct lighting the mounting height should be at least 3.5 m.
In those rooms that may be used for sports, especially badminton, care should
be taken to see that light sources chosen will not cause flicker or stroboscopic
effects; and in most cases HF control gear is essential. Luminaires should be
suitably rated for impact resistance with suitable protection of the lamp should
it become broken. Lighting Guide LG4: Sports lighting(49) should be consulted
for sports applications.
5.7.4
Suspension points
and wiring
It may be necessary to mount temporary spotlights for many functions and
appropriate suspension points should be provided; a space frame ceiling is ideal
for this purpose. If the room has a definable stage area then provision should be
made for mounting front-of-house spotlights in the shape of wall brackets or
spot bars mounted below the ceiling and in smaller rooms that may suffice for
all spotlight mounting. Since wall lighting is often needed for exhibition and
display purposes, a ceiling track round the entire room 1.2 m in from the wall
may be a wise provision if ceiling height is less than 4 m.
Where provision is made for spotlight mounting for stage purposes,
appropriate wiring runs back to the control point/switchboard must be provided
with separate circuits for each outlet point and provision of cables for a suitable
control circuit such as DMX512.
5.7.5
Controls
Multi-purpose rooms will generally be regarded as places of public use and thus
may be subject to specific requirements under legislation such as the Building
Regulations. These may require that the lighting controls be placed such that
they can only be operated by competent staff, which may prove awkward for the
user.
All of the lighting controls should be grouped together so that one
individual can have charge of all; the controls are best placed in an adjacent
room with a window or CCTV monitor into the multi-purpose room.
A multiple scene setting control system should be used if possible with a
number of scenes suited to the multitude of uses. This allows complete
Lighting for particular applications
57
flexibility of control, but also enables pre-set lighting arrangements to be set-up
at the push of a button so that it can be used by inexperienced users, such as a
simple on/off control for initial entry to the space.
5.8
Adjoining
spaces
This category includes foyers, ante-rooms, lobbies and corridors immediately
adjoining those spaces listed above.
5.8.1
Lighting objectives
The functions of the lighting in spaces adjoining teaching and conference spaces
are as follows:
—
to provide for the entrance and exit of the users, bearing in mind
that many people may need to get in and out in a short time
—
to put users, as they approach, in an appropriate frame of mind
for the activity in which they are about to take part
—
in some cases, especially ante-rooms, to provide a social
atmosphere (such spaces are often used as tea and coffee spaces)
—
in some cases, to indicate to visitors the route they should take
to reach their destination, e.g. the lecture theatre in a museum;
in other cases, e.g. a suite of teaching rooms in a college, this may
not be appropriate
—
finally, in many schools there are ‘heart’ or ‘breakout’ areas for
group interaction or project work.
The lighting of an adjoining space should therefore be designed in
parallel with that of the lecture, teaching or conference spaces which they serve.
However, this does not necessarily mean that they should be in the same style,
or have the same illuminance values.
5.8.2
Circulation
Fig. 5.20
Breakout spaces opening
off a central circulation
space and stairwell
(photograph courtesy of
Thorn Lighting)
The circulation routes in a school are its main arteries taking pupils, staff and
visitors from the main gate through to the particular rooms of interest. They
need to be functional in that people need to find their way easily and safely
through the building, even when they are unfamiliar with it. Circulation zones
are often used for chance or ad hoc meetings or as breakout learning spaces (see
Figure 5.20) so these routes also need to incorporate daylight and should be lit
so that good face to face communication can take place.
They will in most cases need to provide means of escape and this will
require emergency lighting according to time of availability and user awareness.
As school and college use is not restricted to daylight hours, a careful risk
assessment should be carried out to determine which access routes are available
for use during hours of darkness and, therefore, whether they require emergency
lighting.
Lighting can provide guidance for the visitor from entrance to
destination, that may be done in two ways. First, the geometry of the luminaires
can imply a direction. Secondly, by the phototropic effect whereby people are
attracted to bright lights. A lighting designer can exploit this tendency by
leading visitors towards brightly-lit areas.
Lighting in corridors must provide for safe movement, and should
provide an illuminance of at least 100 lux at floor level, with a UGR below 25.
There must be appropriate lighting for hazards to be visible; special
consideration should be given to those with visual impairment, where colour
can be used to provide visual contrast. A particular hazard in corridors with
shiny floors is that of water on the floor, which may be present due to spillage,
roof leakage, or from melted snow carried in occupants’ shoes.
The rule for staircase illumination is to light the treads and not the risers.
A lighting level of 150 lux is appropriate and should be provided by positioning
luminaires carefully to avoid distraction. The type and position of luminaires
over stairs may be determined primarily by the requirements of emergency
lighting and thereafter by the proposed installation and aesthetic requirements.
58
Lighting Guide 5: Lighting for education
Fig. 5.21
Circulation spaces often double
up as informal learning or
meeting spaces (photograph
courtesy of Thorn Lighting)
Fig. 5.22
Adequate illuminance provided
in such a way as to cause a
maintenance access problem at
a later date (photograph courtesy
of Thorn Lighting)
However, consideration needs to be given to maintenance access where
luminaires are mounted at height or over the stairs themselves (see Figure 5.22).
Waiting areas
and lobbies
Waiting areas and lobbies immediately adjoining lecture or conference spaces
should be kept tidy and free of visual clutter. As they may be used as social areas,
the illuminance should be about 200 lux and lamps of Ra ≥ 80 should be used.
Unless the height is greater than 4 m above the floor, downlighters should be
avoided as the harsh modelling they create can hinder face to face
communication.
Because activities of this kind may go on at the same time as lectures or
conference proceedings, there should be two sets of doors at the entrance to the
teaching or conference space, to act as both light and sound traps. The designer
should consider that latecomers may be entering a much darker environment
and the entrance lobby and walkways to the seating should be lit with care to
allow for the adaption of the eye to the new illuminance level.
There should be a rear entrance for latecomers to lecture theatres/rooms
and it should be clearly signposted from the main entrance — preferably with a
sign illuminated when lectures are in progress.
If an ante-room for the lecturer is provided its lighting should be of a
standard comparable with a laboratory, office or workshop as appropriate to
allow preparation by the presenter.
5.10 Areas with
display screen
equipment
The lighting for the display screen equipment (DSE) in educational and
conference spaces needs to be appropriate for all tasks performed at that location
and for the duration of the task, e.g. reading from screen or printed text, writing
on paper, keyboard work.
For these spaces the lighting criteria and system should be chosen in
accordance with activity area, task type and type of interior from the schedule in
section 5.2.
The display screen (whether desk mounted, on the speaker’s lectern, or
part of the wall display for interactive teaching) and, in some circumstances, the
keyboard may suffer from reflections causing discomfort glare. It is therefore
5.9
Lighting for particular applications
59
necessary to select, locate and arrange the luminaires, and to control daylight so
as to avoid high brightness reflections.
The designer will need to determine the offending mounting zone and
choose equipment with suitable mounting positions or distributions which will
cause no disturbing reflections.
5.10.1 Luminaire
luminance limits
with downward flux
Lighting can lower the contrast of the presentation on display screens by either
causing veiling reflection by the illuminance incident on the displays surface or
by luminance from luminaires, windows and bright surfaces reflected in the
display. Based on the intended context of use BS EN ISO 9241-307(47) gives
requirements for the visual qualities of displays concerning unwanted
reflections. This paragraph describes luminance limits for luminaires that may
be reflected in display screen equipment for normal viewing directions.
Table 5.4 gives the limits of the average luminaire luminance at elevation
angles of 65° and above from the downward vertical, radially around the
luminaires for work places where display screens, which are vertical or inclined
up to 15° tilt angle, are used.
The effect of higher luminance on the display screen is determined in
part by the display usage. In Table 5.4, ‘Case A’ refers to positive polarity and
normal requirements concerning colour and details of the displayed
information (e.g. when used in office, school etc.) and ‘Case B’ applies to
negative polarity and/or higher requirements concerning colour and details of
the displayed information (e.g. when used for computer aided design (CAD),
colour inspection etc.).
Some tasks or activities may require different lighting treatment such as
lower luminance limits, special shading, individual dimming and so, according
to the task.
Table 5.4 Average luminance limits of luminaires that can be
reflected in flat screens (adapted from BS EN 12464-1(44), Table 4)
Display screen
type
Luminaire luminance limit for stated
screen ‘high state’ luminance
High (> 200 cd/m²)
Medium (< 200 cd/m²)
Case A
≤ 3000 cd/ m²
≤ 1500 cd/ m²
Case B
≤ 1500 cd/m²
≤ 1000 cd/m²
Note: for old type CRT screens luminaire luminance limits are
200 cd/m² for negative and 500 cd/m² for positive polarity
5.10.2 Selection of the
appropriate limit
To help establish whether the correct choice of luminance limit has been made
the designer can use the methodology(50) below and the flowcharts given in
Appendix A1.
First the designer will need to determine the size of the offending light
source (luminaire or window, see Figure 5.23. The visual size of the light source
or the subtended angle (θ ) can be calculated using the equation:
(
d/2
θ = 2 arctan ———
s1 + s2
)
(5.1)
where θ is the subtended angle or visual size of light source (°), d is the distance
of the light source in the direction of the display screen (m), s1 is the viewing
distance (m) and s2 is the distance between the light source and the display
screen.
Then the solid angle (Ω ) delimited by a cone of apex angle θ can be
calculated using the equation:
Ω = 2 π (1 – cos (θ /2))
where Ω is the solid angle in steradians.
(5.2)
60
Fig. 5.23
Lighting Guide 5: Lighting for education
Calculation of visual size
in degrees (the luminaire
and distance are not to
scale but enlarged to
show the angle clearly)
Luminaire
d
s2
θ
s1
Display screen
The visual size of a luminaire is highly dependent on the luminaire, the
direction of viewing and the distances between the luminaire, the screen and the
viewer. A 1° source is about the size of a circular downlight or a fluorescent
troffer viewed crosswise. Other luminaires may be nearer to 3–5°.
The visual size of a window is also variable. Studies of student positions
in typical classrooms indicate window sizes of, typically, 10° and 15°.
The tables given in Appendix A1 use a 95% satisfaction criterion, that is
to say by this method of calculation and luminance limit, 95% of users would not
experience problems with display screen equipment veiling reflections.
5.10.3 An alternative
approach
As screen technology is developing at a faster rate than that of conventional
lighting it is far more appropriate to define the performance of the screen that is
required, rather than compromise the lighting comfort of the user of a space by
restricting the available light. Given that in most learning spaces the computer
screen is not the main disseminator of knowledge, it seems inappropriate to
limit the lighting designer’s choices for lighting the speaker, teacher or pupil
simply due to poor application of display screen technology. To do so would recreate the ‘cave’ effect inadvertently produced in many offices and classrooms of
the 1980s and 1990s.
Most luminaire manufacturers issue accurate information on the
luminance of their equipment at angles above 65° from the downward vertical.
Once the lighting designer has reached a lighting solution that provides for the
performance, efficiency and comfort of the users of a learning space, the screen
brightness limitations suited for use in that space should be defined. For
instance, it should be possible to require suppliers of laptop or desktop
computers screens for classroom use to provide screens capable of a minimum
of 3000 cd/m2 with a matt finish and available tilt of not more than 35°, rather
than limit the luminaires to 200 cd/m2, based on an inadequate knowledge at the
time of the lighting design as to what display screens may be used. Given also
that, on average, screens are replaced every 5 years, whereas luminaires may last
in excess of 15 years, this approach makes sense in both economic and
sustainability terms in order to provide a good quality lit environment. Lighting
control for both the electric lighting and daylighting should still be provided.
5.11 Laboratories,
workshops and
other practical
learning spaces
Rooms used for practical work, i.e. laboratories, workshops, art rooms, food
technology/catering, electronics, craft rooms and similar applied learning
spaces, involve visual needs and tasks that are the same as those found in
industry. This is particularly so if the room contains fixed equipment, e.g. a
workshop with lathes and other machine tools.
Lighting for particular applications
61
The reader should consult the Code for Lighting(8) for advice on
laboratories, workshops and textiles rooms. However, many rooms used for
practical work have to serve a wide variety of purposes and the visual needs may
be different for each.
In recent years there have been considerable changes in the way
traditional subjects have been taught. Teaching spaces are increasingly
becoming more flexible in use with functions ranging from industrial to office
environments. The computer is no longer confined to special rooms — personal
and laptop computers may be used almost anywhere.
A very large range of activities are to be found in design and technology
departments and they may change throughout the course of a year. The
illuminance over the working plane (0.85 m above the floor) should be above
500 lux, and UGR 19. The UGR may be raised to 22 for preparation areas and the
illuminance should be raised to 750 lux for art rooms in specialist art colleges. If
work involving accurate judgement of colour (e.g. art, dyeing etc.) is to be done,
the lamps should be of Ra = 80 or better in most educational buildings, but in
specialist art and textile colleges/faculties Ra = 90 would be more appropriate.
Visual tasks such as sewing will require local task lighting.
In all these spaces the teacher occupies no fixed position but spends time
at the benches, machines and worktables as needed. The main requirement is for
good supervision with the ability to determine detail and texture being
important in most subjects, hence good modelling is required with some
flexibility to control the direction of light and to reduce or omit daylight when
necessary. In most rooms there may be a teaching wall from where more formal
presentations will take place with the students sitting or standing by their
machines, benches or tables, but in some establishments presentations and
discussions take place in separate spaces with only practical work carried out in
specialist rooms. These separate spaces may be lecture rooms, classrooms,
seminar rooms or small group rooms, and the design of these spaces should
follow the advice given in earlier chapters.
Laboratories in tertiary education and research will generally have fixed
furniture (see Figure 5.24) but in schools and colleges may take a less formal
arrangement with movable tables and fixed wall benches or service pillars so
that a variety of layouts can be provided. In both cases, as with design and
technology, there is usually a teaching wall. As with other teaching rooms in
schools, it is a requirement that they are primarily daylit, but here it is more
important that sunlight can be excluded because of disability glare and the
danger of rendering experimental flames invisible.
Fig. 5.24
A typical laboratory
showing a fixed
arrangement, teaching
wall and workstations
situated close to daylight
(photograph courtesy of
Thorn Lighting)
62
Lighting Guide 5: Lighting for education
Where fast moving machinery is in use care should be taken to avoid
stroboscopic effects by use of high frequency control gear. Where dust or
moisture risk exists the lighting should be a minimum of IP44. In specialist
laboratories in higher education it may be necessary to provide luminaires of
IP65 with a clean room classification. In this case advice should be sought in line
with good practice in the clean room/pharmaceutical industries covered in SLL
Lighting Guide LG1: Industry(51).
In laboratories some processes may need terminating before evacuation.
It is therefore necessary to have adequate high risk emergency task lighting in
those specific locations where a visual task must be performed prior to
evacuation. Lighting to the escape routes, or open areas from laboratories and
workshops will be required to ensure safe passage past any risks from machinery
or other hazards.
5.12 Libraries
Fig. 5.25
Lighting coordinated with
library shelving to provide
sufficient vertical
illuminance to the lowest
shelf (photograph courtesy
of Thorn Lighting)
In libraries the designer needs to allow for two main tasks: (a) finding the
correct book, and (b) reading or study. In addition, there are a number of other
considerations such as lighting for using computers and accent lighting for
display purposes. Lighting in each case calls for a different approach. Physically
finding a book (rather than looking it up on a computer database) requires
vertical illuminance on the spine of the book and, in the worst case, this may be
just above floor level. Therefore, 200 lux on a vertical plane at just above floor
level is required and the designer should remember that the library user will
create a shadow when in the vicinity of the shelving, hence light from more than
one direction is important. Use of floor finishes with a relatively high
reflectance can help.
For computer and reading based tasks 300 lux is suitable for most users
and in some libraries that are open to the wider adult community this may be
raised to 500 lux for reading tasks by the addition of local task lighting where
appropriate, such as at planned reading desks. However, it would not be
acceptable to light the entire space to a higher level for a few users who may be
present only occasionally. Lighting for students with impaired vision needs
careful design and suitable aids to reading should be considered. It should be
borne in mind that for some impairments higher illuminance, in itself, may not
be the solution.
Care should be taken to incorporate daylight were practical, protecting
valuable reading matter where necessary from heat or ultraviolet damage but
maximising energy savings and providing a higher quality of reading light as far
as practicable.
Lighting for particular applications
5.13 Sports halls
and gymnasia
Fig. 5.26
It is possible to provide
daylight to sports halls
with careful design;
electric lighting should
cater for many differing
uses (photograph courtesy
of Thorn Lighting)
63
It is generally considered that daylight is beneficial in sports halls and
gymnasia. However, windows and roof lights are frequently excluded except at
high level because the sun and sky can cause both disability and discomfort
glare to users who are moving quickly and often with an upward field of view.
Also there is a risk of damage to glazing from some sports. Reflected glare from
shiny surfaces and particularly floors can also be a nuisance. If daylight is
provided, screening facilities for use when necessary should be available. There
should be little objection to the use of natural lighting within sports halls
providing it is well considered and appropriate. The provision of high quality
internal spaces with attractive daytime environments is a significant aspect in
attracting user groups.
There are considerable benefits in terms of environmental sustainability
and potentially lower running costs in being able to complement electric
lighting with natural daylighting. However, using natural light in a sports hall
requires very careful consideration because of difficulties in controlling glare
and ensuring reasonably constant and uniform levels of lighting.
Appropriate lighting is vital in sports halls to allow activities to take place
that often demand difficult visual tasks, for instance tracking a fast moving
shuttlecock against a similar colour background. The design issues are complex
and optimising natural daylight and integrating it with well designed electric
light requires that the form, fabric, internal layout and systems of a building are
considered holistically. For natural lighting generally, north light is considered
most appropriate.
To enhance the visual environment, it is suggested that luminaires with
both upward and downward light should be utilised. There should be some
control to keep glare to a minimum and the light distribution should provide
adequate light on vertical surfaces.
Lamps and luminaires should have wire guards or other impact-resistant
protection. Sports halls and gymnasia in schools are often used for non-sporting
events, including examinations, and therefore consideration must be given to
the lighting required for these events and supplementary arrangements
provided if necessary. Control strategies should be such as to make it difficult
simply to switch ‘all on’ lighting because it is easy to do so; scene switching
should be clear and functional.
Because of the high mounting of the luminaires, maintenance of the
lighting installation will be difficult unless special access facilities are provided.
The use of long life lamps in these circumstances should be examined.
Reference should be made to Lighting Guide LG4: Sports lighting(49).
64
Lighting Guide 5: Lighting for education
5.14 General
purpose halls,
drama and
dance studios
Very often there will be a need for a large space within an educational building
to cater for activities ranging from examinations to drama. The design will
depend on the range of activities. Blackout will almost certainly be required for
drama use, as will a degree of flexibility in the lighting dependent on the range
of uses envisaged and the budget. If the budget is limited, a general lighting
installation of luminaires that provide both upward and downward light should
be used. The installation should meet the most stringent requirements in terms
of activity, allowing the luminaires to be simply controlled to provide some
flexibility. To complement this there should be a system of wiring that allows
supplementary theatre lighting equipment to be installed when needed.
For teaching of GCSE, A-level and degree level drama courses, a good
standard of stage and drama studio lighting will be required (see Figure 5.27).
Fig. 5.27
Floor trap with sockets
(on stage if fixed stage)
Mounting positions for
(upper) theatre and
(lower) drama room
lighting
Stage may be whole
width of hall or be
platform only
Rear stage barrel
for back lighting
Dimmer racks
Socket for control
desk for setting-up
lighting
Possible proscenium
arch location
Wall sockets
high up on wall
Socket for control
board during
performance
Pre-wired
lighting barrels
across entire
room
Window should
have full blackout facilities
Sound and light
control desk
Front stage barrel
(deep stages may
require one or
more intermediate
barrels)
Front of stage
barrel to light
those on
fore stage
Lighting for particular applications
Fig. 5.28
Dance studios should use
daylight whereas drama
may require complete
blackout (photograph
courtesy of Cundall Light4)
5.15 Lighting for
whiteboards
and projection
screens
65
In halls likely to be used for concerts, theatrical and dance productions it
may be necessary to arrange for an adaptable stage lighting system to be installed
so that each event can be appropriately lit. Lighting barrels will need to be
placed above and in front of the stage so that stage lights can be positioned to
light the faces of people performing on all areas of the stage. To achieve this,
lighting needs to come from about 45° above and 45° to either side of any
position on stage. This will involve using wall mounted brackets and additional
lighting power and control connections. Where there is a fixed stage, floor-traps
with stage lighting sockets should be located on either side for side-lighting
dance, and for special effects lighting. The lighting installed in spaces for music
recital or performance should be carefully considered in terms of the noise the
luminaire components and controls may make. Resistive or inductive
components should be mounted outside of the space or within sound insulating
enclosures.
High level, wall mounted and stage sockets should all be wired back to a
dimmer position on one side of the stage.
For larger halls there may be a need to provide an additional dimmer
position at the back of the hall for controlling the lighting during a production.
Drama and dance studios are used primarily for the teaching of drama
with some need for small dance class use. Whilst windows and daylight are still
required to allow flexibility of use for these rooms there may be a need for full
blackout facilities during lessons.
Drama lessons are used to teach group skills, focusing on social and
personal development, where general mood lighting across the whole studio is
needed, as well as performance and stage craft skills, such as set and lighting
design, where full theatre lighting is needed for performance use in any area of
the room.
To achieve this there needs to be a basic structure of lighting points across
the space for locating lights in any part of the room. Often the most convenient
solution is to place a series of pre-wired lighting barrels at intervals across the
width of the room. The lighting sockets should all be wired back to a dimmer
position located in one corner of the room.
The vast majority of educational spaces now use whiteboards (normally with a
gloss finish) and, in an increasing number of cases, interactive whiteboards.
Inherent in these technologies are surface finishes prone to veiling reflection
and, in the latter case, projected images that may struggle to compete with high
luminance sources (most commonly sunlight, but in some cases electric or
general ambient daylight). It is therefore essential that all whiteboards be
treated carefully.
Note that gloss whiteboards cannot satisfactorily be used as projection
screens as the high gloss will cause veiling reflections from the projector.
To keep reflections to a minimum, whiteboards should be mounted
vertically on walls perpendicular to the window wall. They are best lit by ceiling
mounted luminaires (see Figure 5.29) or those specifically designed for the
purpose (see Figure 5.30). Where older black chalkboard surfaces are still in use,
the illuminance on the surface should average 500 lux, with a uniformity of 0.7;
this may be reduced in the case of lighter colour boards to maintain an average
luminance across the board available to the eye of 80–160 cd/m2. Effective
reflectance for coloured boards are: whiteboard 85%, blackboard 5–10%,
green/blue 20%, yellow/green 30%.
Where a separate whiteboard luminaire, or luminaires, are fitted they
should have a manual override switch positioned local to the board for ease of
use.
Care should also be taken to avoid excessive luminance on the interactive
media board. In some cases, those based on plasma technology, luminance in
excess of 200 cd/m2 may cause problems. In the case of modern close projection
systems the luminance may be considerably higher than those imposed for
66
Lighting Guide 5: Lighting for education
laptops and other display screen equipment; in some cases luminance up to
6000 cd/m2 may be acceptable but the designer is strongly advised to investigate
the performance of the actual screen to be used.
Fig. 5.29
Whiteboard luminaires
need to be carefully
positioned
Whiteboard luminaire must be installed
within the shaded area to avoid reflections
in the board to the nearest viewer
0
0
Where students may sit close to an interactive
whiteboard the board light may need to be
switched off to reduce glare
Fig. 5.30
Specific whiteboard
lighting positioned to
reduce glare and with
matt projection screen
mounted separately
(photograph courtesy of
Thorn Lighting)
5.16 Lighting and
visual aids
Visual aids are often used for teaching, most commonly interactive whiteboards
and computer based projectors as well as television and video equipment. For
the use of these teaching aids it may be necessary to provide a lower level of
lighting so that the presentation can be seen comfortably and clearly. Curtains
or window blinds will need to be chosen carefully to match the capabilities of
the existing equipment and in some cases blackout blinds that fit into slots
surrounding the window reveals may be used. Care should be taken to make sure
lighting controls and blinds are easy to use to avoid the common ‘blinds closed,
lights on’ mentality. Specification of suitable high brightness projectors should
enable most daylit spaces to retain some natural light contribution at all times.
Sufficient light should be provided to enable notes to be taken during the
presentation, and an illuminance over the seating areas within the range
15–30 lux is suitable. High luminance elements from luminaires within the field
of view may under certain conditions make the viewing of the presentation
difficult and care should be taken, perhaps specifying a required shielding angle,
Lighting for particular applications
67
to make sure a glare-free view of the screen is possible. Also, light should not fall
onto the projection screen and it should not be possible to see reflected images
of luminaires or windows on the screen surface of television monitors.
5.17 Lighting for
pupils with
visual and
hearing
impairments
Lighting must take into account the different needs of children with special
educational needs (SEN) and disabilities. Children with impaired vision, for
example, need lighting levels that enhance their sight. Those with hearing
impairment need clear visibility for lip-reading and signing, for orientation and
using signage and wayfinding. Safety is a key factor; poor visibility and poor
surface contrast may contribute to accidents. Input from a lighting specialist is
recommended where there are complex visual needs.
A school’s orientation and any natural shading on the site should be
considered at the outset, including the location of spaces that generate the most
heat and the need for and detailing of shading devices. The Royal National
Institute for the Blind (RNIB) and similar organisations can advise on specialist
environments for children with visual or multiple impairments. Designs should
avoid glare, silhouetting, reflections, shadows and any other interference that
causes visual confusion. For instance, a teacher’s or child’s face could be in
shadow against a window or bright or highly reflective surfaces, or have shadows
cast by electric lighting. Good tonal contrast is important.
There will be times when teachers will want to change the mood of a
space to create a more calming or stimulating environment. Window blinds and
electric dimming can help, as can local controls.
5.17.1 Daylighting
Daylighting is important for all schools, and children with limited mobility in
particular benefit from a connection to the outdoors and a view out. However,
some pupils with SEN may be particularly sensitive to glare from direct or
reflected sunlight, so it is important to be able to control natural light entering
the space. This may also be particularly important when providing the right
visual conditions for viewing whiteboards and projection screens.
The window wall should be light in colour. A brightly lit outdoor view
through a window can be glaring against a dark wall — a particular hazard at the
end of a corridor. A minimum average daylight factor of 4–5% is considered the
optimum (on the working plane) for schools with children with SEN and
disabilities; an acceptable uniformity ratio should be maintained by providing a
minimum point daylight factor of 2% up to 0.5 m from the wall and avoiding
under-lit areas furthest from windows. This applies to learning, circulation and
assembly spaces. In deep spaces lit by windows in one wall only, ceilings may
need to be higher than average with high levels of light reflectance may be
required. Where there is a number of children with visual impairment or
sensitivity to light, or where there are conflicting needs, specialist lighting
advice may be needed.
5.17.2 Electric lighting
Light fittings must be low-glare, with strict avoidance of mains frequency
flicker and unwanted noise. It may be necessary to avoid visible light sources,
over changing-beds or therapy couches, for example. Uplighters and use of
coloured light synchronised to particular time cues or events during the day
may be more suitable for some children with autism.
Automatic sensors that switch off lighting when no movement is detected
may not be suitable for children who are less mobile. Switches may be useful in
teaching children how to use them.
5.18 Local task
lighting
Without doubt there has to be a fundamental change in the use of light in all
buildings. No longer is it ecologically sound to light for the neediest user as a
blanket measure. The approach must be one of allowing sufficient light for the
normal users and the most common task. In addition, the designer should allow
for the needs of any other users of the same space through the use of additional
task lighting. This task lighting can be by the provision of controls, for instance
68
Lighting Guide 5: Lighting for education
the setting of the normal scene in a classroom to 300 lux, but allowing a scene
that increases this to 500 lux if required. Alternately, the designer could allow
for the lower level using ambient lighting, including daylight, and top-up this
level local to a particular task; for instance, by providing an ambient 200 lux
vertical illuminance in a library with desk mounted reading lighting to 500 lux
at reading positions.
Careful design of task luminaires is needed, especially in cases of SEN
students. For all students it will be necessary to ensure power leads are kept out
of reach by careful cable management and routing through desks. It will be
necessary to limit the temperature of any luminaire components available to
touch or likely to be in advertently touched, perhaps whilst leaning over a book.
Where luminaires are used in close proximity to students it will be necessary to
limit surface temperatures to below that which will cause skin damage.
Local task lighting should be dimmable and controlled such that the
lighting distribution does not extend beyond the intended task and removing
the possibility of glare to other users or equipment. Local switching will be
required, preferably linked to a room override function to ensure lighting is
switched off when not required.
5.19 Exterior
lighting
Fig. 5.31
External lighting should
guide, welcome and
provide a sense of safety
whilst satisfying the need
for good quality CCTV
images and minimal light
nuisance (photograph
courtesy of Cundall Light4)
When considering the external lighting the designer should take the opportunity to consider not only the functional requirements of external lighting but
also the amenity aspects and the benefits that good exterior lighting can bring.
Advantage should be taken where appropriate to provide landscape illumination
wherever possible and to add a sense of visual enhancement to interesting
architecture, sculptures or building structures. Overall, though, lighting to
educational buildings will be for safety and security.
Entrances should be treated in the same way as entrances to leisure
centres or retail outlets. The designer should ensure they provide an attractive,
welcoming appearance to all the entrances, access routes and surrounding areas
for staff and students alike. Environmental planning will also require the
lighting designer to be mindful of the light nuisance that may be caused.
Although difficult to alleviate totally, it can be reduced considerably by careful
consideration of the product design and positioning of luminaires.
Exterior lighting should at the very least provide both pedestrians and
vehicular traffic with good visual guidance around the site.
Lighting for particular applications
69
In addition to the visual tasks it should also be designed to provide
pedestrians with a ‘psychologically safe’ environment. Colour rendering,
installation efficacies and maintenance issues must all be considered as well as
the luminaire positioning relative to CCTV and local residences.
5.19.1 General performance See Table 5.5. Exterior lighting should comply with minimum lamp and gear
efficacy targets of 80 lm/W for colour rendering light sources less than Ra = 60
requirements for
and
with 70 lm/W for light sources greater than Ra = 60.
exterior spaces
Where there is increased use by those with disabilities, the designer may
decide to increase these levels appropriately but only in zones specifically
designed to ease disabled access.
Table 5.5 General performance requirements for exterior spaces (source: BS EN 12464-2(52))
Type of area task or activity
Em (lx)
General circulation areas:
— walkways exclusively for pedestrians
— traffic areas for slowly moving vehicles
(max 10 km/h, e.g. bicycles)
— regular vehicle traffic (max 40 km/h)
— pedestrian passages, vehicle turning,
loading and unloading points
Parking areas:
— light traffic e.g. parking areas of schools
— medium traffic e.g. parking areas of
colleges or universities, office buildings,
sports and multipurpose building complexes
— heavy traffic e.g. parking areas of
major conference venues, major sports
and multi-purpose building complexes
5.19.2 Sports pitches
Ra (min)
Uo (min)
GRL (max)
5
10
20
20
0.25
0.40
50
50
20
50
20
20
0.40
0.40
45
50
5
10
20
20
0.25
0.25
55
50
20
20
0.25
50
The designer should avoid the desire to over-specify sports pitch lighting in the
view that it will extend community use. Generally all educational facilities will
only require a maximum of Class III play(32), i.e. suitable for recreation or schools
sports use including physical education. In cases of colleges or universities with
specialist sports courses, the designer may need to increase this sensibly in line
with the needs of the college.
Where the establishment requires lighting to higher than Class III the
design must provide the additional levels by luminaires on separate control
circuits enabling a stepped switched approach and giving staff the ability to
minimise energy use to the most appropriate level. Lighting controls for the
higher levels should be accessible only to staff.
Generally external sports areas are likely to have a multi-purpose use and
the designer may need to satisfy a number of requirements. Furthermore the
designer should consider the realistic quality of play, type of material used for
Table 5.6 General performance requirements for exterior sports pitches to BS EN 12193(32)
Type of area task or activity
Basketball
Football (outdoor)
Handball (outdoor)
Hockey (outdoor)
Netball (outdoor)
School sports
Tennis (outdoor)
Class
Em (lx)
III
III
III
III
III
I
II
III
III
75
75
75
200
75
750
500
200
200
Ra (min)
20
20
20
20
20
60
60
20
20
Uo (min)
0.50
0.50
0.50
0.70
0.50
0.70
0.70
0.50
0.60
GRL (max)
55
55
55
55
55
—
—
—
55
70
Lighting Guide 5: Lighting for education
the playing surface and the range of visual acuity issues raised by extended
community use. In such cases the designer may find the guidance levels offered
by Sport England more applicable, see Table 5.7.
Table 5.7 Multi-use games areas to Sport England standards
Surface
Game
Em (lx)
(principal
playing area)
Painted open textured macadam
Principal sports
Tennis, mini-tennis, basketball
Secondary sports
Netball
Open textured macadam
Principal sports
Netball (AENA Category 1 and 2 courts)
Secondary sports
Tennis, mini-tennis, basketball
Polymeric surfaced
Principal sports
Netball (AENA Category 3 court)
Secondary sports
Tennis, mini-tennis, basketball
Principal sports
Five a-side, football training, athletics training
Sand filled/dressed synthetic turf
Principal sports
Hockey, football and five-a-side football
Secondary sports
Ra
Uo
GRL
MF
CCT
400
400
65
65
0.7
0.7
50
50
0.8
0.8
4000
4000
400
400
65
65
0.7
0.7
50
50
0.8
0.8
4000
4000
400
400
200 (full
lighting and
training)
65
65
—
0.7
0.7
0.7
50
50
—
0.8
0.8
—
4000
4000
—
350 (full
lighting
200 (training)
0.7
Lacrosse, rugby training (not scrummaging),
and athletics training
350 (full
lighting
200 (training)
0.7
Note: in all cases overall minimum maintenance factor = 0.8, glare rating < 50, colour rendering value (Ra) > 65,
colour temperature ≥ 4000 K
5.19.3 Light nuisance
Fig. 5.32
Use of zero cut-off
lanterns aimed from the
perimeter inwards restricts
to the minimum light
nuisance (photograph
courtesy of Thorn Lighting)
In modern exterior design there is very little justification for poor control of
light nuisance from any educational site, especially those that sit within the
community. Whilst there are arguments for road lanterns using shallow bowl
optical design, to compromise some upward light for maximum spacing and
therefore better overall performance, the case for all other exterior lighting is not
as strong.
Particularly for educational premises, the designer should comply with
the requirements of BS EN 12464-2(52) with respect to restricting light nuisance.
Furthermore, there is little basis for the decision that new buildings in urban or
Lighting for particular applications
71
suburban zones should be allowed to waste light more than those in rural
districts. Hence, for all educational premises, the designer must aim for the
minimum limits given against each zone for the technical parameters given in
Table 5.8. The zones are defined in Table 5.9.
For colleges and universities specialising in sports the use of zone E4
limits may be justified, subject to geographic location for the sports pitch
lighting, provided suitable controls are installed to ensure the lighting does not
remain on when not required.
Except for high performance sports pitches in specialist colleges and
universities, exterior lighting should maximise the use of zero cut-off lanterns,
those luminaires that emit no upward light when normally installed.
Table 5.8 Performance requirements to limit light nuisance (adapted from BS EN 12464-2(52)
Table 2, by permission of the British Standards Institution)
Parameter
Application conditions
Value of parameter for stated
environmental zone
E1
E2
E3
E4
Upward light ratio (ULR)
Ratio of luminous flux incident
on horizontal plane just above
luminaire in its installed position,
to total luminaire flux.
0
0–5
0–15
0–15
Illuminance in vertical
plane (Ev ) (lux)
Pre-curfew
Post-curfew
2
0
5
1
10
2
10
2
Luminous intensity emitted Pre-curfew
by luminaires (I ) (cd)
Post-curfew
2500
0
7500
500
10 000
1000
10 000
1000
0
5
10
10
50
400
800
2800
Building facade luminance
(Lb ) (cd/m2)
Taken as the product of the
design average illuminance
and reflectance factor
divided by π
Sign luminance (Ls ) (cd/m2) Taken as the product of the
design average illuminance
and reflectance factor divided
by π or for self-luminous
signs the average luminance
Table 5.9 Classification of environmental zones
Zone
Surrounding
Lighting environment
Examples
E1
E2
E3
E4
Natural
Rural
Suburban
Urban
Dark
Low brightness
Medium brightness
High brightness
National parks and protected sites
Industrial or residential rural areas
Industrial or residential rural suburbs
Town centres and commercial areas
Table 5.10 Threshold Increment limitations from sports and road lighting installations
(reproduced from BS EN 12464-2(52) by permission of the British Standards Institution)
Threshold increment for stated road lighting/road classification
No road lighting
Road classification
M5
15% based on
adaptation luminance
of 0.1 cd/m2
5.19.4 Road lighting
15% based on
adaptation luminance
of 1 cd/m2
M4/M3
15% based on
adaptation luminance
of 2 cd/m2
M2/M1
15% based on
adaptation luminance
of 5 cd/m2
Road lighting requirements are currently detailed in BS 5489-1(53) and BS EN
13201: Parts 2 and 3(54,55).
Entrance and exit points will often connect with major traffic routes and
the lighting should be graded, in order to avoid sharp contrast with the external
roadway lighting. Roads lighting standards should be considered based on
realistic vehicle speeds, pedestrian and cyclist usage.
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Lighting Guide 5: Lighting for education
5.19.5 Car parking
Guidance for all types of exterior lighting, including recommended illuminance
levels, can be found in detail in BS 5489-1(53) and summarised in the lighting
schedule (Table 5.5). On new installations it is advisable to ensure a that a ‘safe
by design’ policy is initiated early in the project. This should include advice on
CCTV together with the positioning and type of lighting required. The external
lighting should include all entrance and exit points, and all pathways that link
with buildings. All exterior luminaires should use high output, good colour
quality, low energy lamps. Care should always be taken to avoid or minimise any
light nuisance.
All lanterns should be of zero upward light distribution. For smaller car
parking areas, it may be possible to provide illumination from the periphery and
also from buildings in the immediate vicinity. Larger areas will require columns
to be located either centrally or on the boundaries of the car parking area. The
location of the columns should take into consideration the parking bays. Where
columns are used, their height and position relative to adjacent access roads
must be taken into account. Access for maintenance purposes should also be
considered and, wherever possible, the column height should be such as to allow
on-site maintenance to be carried out without the need for specialist access
equipment.
5.19.6 Pedestrian footways
Footways that are not well illuminated from elsewhere must be provided with
adequate illumination to ensure people’s safety during hours of use. Wall
mounted luminaires from adjacent buildings or low-level luminaires can be
provided in the absence of street lighting. If low-level luminaires are utilised,
these must be of the vandal resistant type and incorporate long life, low energy
lamps. If CCTV is operational, the minimum illuminance for the CCTV equipment
must be taken into account, as well as care in the positioning of the luminaires.
Particular attention should be given to routes that allow passage to plant rooms
where maintenance staff may require access after dark. These access points,
which may be at roof level, must also be adequately illuminated. Similar special
consideration must be provided for routes to staff on-site residential areas,
which may be in regular night-time use.
5.19.7 Security lighting
There are many areas that pose security risks around educational sites,
particularly from vandalism or theft. Attention should be given to areas of
darkness that may encourage unauthorised persons to gain access or linger in
the area.
5.20 Emergency
lighting
In all of the rooms covered by this Lighting Guide, large numbers of people may
gather together. It is therefore necessary to provide emergency lighting, which
is defined as lighting that will enable people to see their way out of a building in
the event of the normal lighting failing.
It must be stressed that it is not the function of emergency lighting to
enable normal activities to continue within a building if the main power supply
should fail; such lighting is referred to as standby lighting and is not normally
provided in educational and conference premises.
Certain elements of the Building Regulations put size limitations on
rooms inferring that anti-panic lighting is not required. However, the designer
must record a risk assessment for the space, specifically under the Regulatory
Reform (Fire) Order(56) in England and Wales. It should be noted that where
there is open access, public assembly, reconfigurable furniture and access after
dark to people unfamiliar with the space the risk of injury on lighting power
failure is likely to be significant and may be even greater if the likely influences
of age, illness, alcohol or drugs are taken into account.
5.20.1 Escape route
signage
It is important that all exits, available for use in an emergency, are clearly
signposted and are visible at all material times. The sign should be illuminated
by normal and emergency lighting systems. If exits are not directly visible, route
Lighting for particular applications
Fig. 5.33
Example pictogram from
BS EN 1838
73
indicator signs with an appropriate directional arrow should be used. The style
and details of the safety signs are defined in BS 5499(57,58). ISO 3864(59) gives the
internationally agreed formats of exit signs and safe condition signs. The
designs consist of a rectangular or square shaped frame with a white pictogram
on a green background. The green area must be more than 50% of the total area
of the sign and the colour must conform to ISO 3864-1(59). As the pictograms can
differ in style and content, it is important to consult the enforcing authority for
a particular project on its interpretation prior to choosing the signs. The
preferred style of escape signs is shown in Figure 5.33, which has been
reproduced from BS 5499-4(57), BS EN 1838(60) and BS 5499-1(58).
A summary of the requirements for safety signs is given in Table 5.11.
Table 5.11 Summary of requirements for safety signs
Parameter
Requirement
Viewing distance
100 × height of externally illuminated sign
200 × height of internally illuminated sign
Minimum 2 m above floor
50% of design value in 5 s
100% of design value in 60 s
1 hour
Mounting height
Response time
Minimum duration
5.20.2 Escape route
illumination
Escape lighting should provide adequate visual conditions and directions for
safe passage on escape routes and allow occupants to reach escape routes from
open areas. It should allow fire alarm call points, fire lighting equipment and
safety equipment to be identified. It should allow hazards (stairs, intersections,
slopes) and hazardous processes to be identified and made safe during
evacuation.
In general, students will be familiar with the site layout and the safety
provisions. They should therefore be able to make an orderly evacuation during
an emergency. However, in some educational buildings there may be activities
and processes that are hazardous and have to be terminated before evacuation.
These are referred to as high-risk areas.
In most educational premises there is likely to be public access for
extracurricular activities and adult education, therefore there are likely to be
large numbers of people who will be unfamiliar with the premises, layout and
escape procedures. Here, much anxiety and confusion may be alleviated by
strategically placed escape signs. At least one sign must be visible from all parts
of the premises at all material times. Such signs should permanently indicate the
directions to exits from the premises or places of safety. Escape areas and routes
must also be illuminated adequately and appropriately.
In high-risk areas, a higher illuminance must be provided at positions
where a visual task has to be performed prior to evacuation or where people have
to pass by these dangers along the escape route.
In all escape areas and spaces, the emergency lighting system should be so
designed that the light it provides fills the occupied volume of the space used for
evacuation.
In addition, the design should be based on the minimum-light-output
condition of the luminaire and should be based on direct light only. The
contributions by room surface inter-reflections should be ignored.
However, for lighting systems using indirect luminaires or uplights,
where the luminaire works in conjunction with a surface, the first reflection is
taken to be the direct light and subsequent reflections should be ignored.
5.20.3 Glare
High contrast between a luminaire and its background may produce glare. In
escape route lighting, the main problem will be disability glare, in which the
brightness of the luminaire may dazzle and prevent obstructions from being
seen, see Figures 5.34 and 5.35. Such glare may be created, for example, by the
74
Lighting Guide 5: Lighting for education
Glare zone
60°
60°
Contributory
Line of sight
Fig. 5.34
Glare in direction of
escape
180°
Table 5.12 Luminaire mounting heights and maximum luminous
intensity
Mounting height
above floor level,
h (m)
180°
Fig. 5.35
beam of a twin spot emergency floodlight seen against a very dark background
or placed at the end of a corridor.
The disability glare level to which an individual is subjected is related to
the luminous intensities of the luminaires in the visual field. The glare can be
minimised by restricting the luminous intensity of all luminaires in the field of
view. The sensitive field of view is taken to be in the zone 60° to 90° (in
elevation) for level routes/areas and the whole of the lower hemisphere for nonlevel routes/areas, as shown in Figures 5.34 and 5.35. The maximum permissible
luminous intensity of an individual luminaire in the glare zone is related to
mounting height, and the limits are shown in Table 5.12. The limits have to be
calculated for the maximum emergency lighting lumen output.
Glare on stairs
5.20.4 Luminaire locations
h
2.5 ≤ h
3.0 ≤ h
3.5 ≤ h
4.0 ≤ h
4.5 ≤ h
<
<
<
<
<
Maximum luminous intensity, Imax (cd)
Escape routes
and open areas
2.5
3.0
3.5
4.0
4.5
High-risk task
area lighting
500
900
1600
2500
3500
5000
1000
1800
3200
5000
7000
10000
At points/places of emphasis, position a luminaire at or within 2 m measured
horizontally:
(a)
at each exit door intended for use in emergency
(b)
near stairs so that each flight of stairs receives direct light
(c)
near any change in level
(d)
at mandatory emergency exits and safety signs
(e)
at each change of direction
(f)
at each intersection of corridors
(g)
outside and near each final exit
(h)
near each first aid post
(i)
near each piece of fire fighting equipment
(j)
near each alarm and call point
(k)
in lift cars
(l)
in toilets, lobbies and closets over 8 m2
(m)
in toilets, lobbies and closets less than 8 m2 without borrowed
light
(n)
in control and plant rooms
(o)
in motor generator rooms use self-contained luminaires
(p)
each side of automatically closing doors
(q)
immediately outside the exit from the premises to the place of
safety.
Note: if (h), (i) and (j) is not an escape route or area, a minimum of 5 lx on
the floor should be provided.
Lighting for particular applications
75
5.20.5 Choice of systems
Emergency lighting systems are usually powered from batteries or generators
that are automatically triggered by a detection system as soon as the mains
system fails. The system duration or category is defined by the period the system
is able supply power to the load, usually given as 1 or 3 hours. In most
educational premises 1 hour duration is sufficient, however for premises used by
those with limited mobility longer durations may be required.
Emergency lighting power systems in educational premises may be
integral or centrally powered; using whichever system makes sense primarily
from a safety point of view.
The designer must consider the environmental impact of emergency
lighting batteries, lamps and power use, though as a secondary consideration to
that of safety. Consideration of LED emergency solutions may offer reduced
quantities of batteries, extended battery life, extended light source life and
reduced parasitic power. However, the designer should research carefully the
claimed performance of LED systems and understand the issues until the
performance of such systems is regulated by suitable European standards.
5.20.6 Classification of
systems
There are a number of ways that emergency luminaires can operate:
—
Non-maintained (NM): the lamp is only lit when the mains fail
and is operated by an emergency power source.
—
Maintained (M): the lamp is lit at all material times and is
powered by the mains supply under normal conditions. In an
emergency, when the mains fail, an emergency power source cuts
in to power the lamp.
In all cases, where a battery is present, it is charged by the mains supply. Where
the public are present, ‘maintained’ exit signage should be used.
5.20.7 Planning schemes
Fig. 5.36
If this equipment is sited
along an escape route it
will require 1 lux from
luminaires positioned
within 2m horizontal
distance
The emergency escape luminaires may be stand-alone bulkhead units or
integrated recessed, surface, pendant luminaires or uplights, but close attention
should be paid to the positioning and mounting of these luminaires. Luminaires
placed too low, especially along corridors, may be obscured by the movement of
people and be subject to vandalism. If placed too high, for example direct on a
very high ceiling, the luminaires may be obscured by layering of smoke in the
event of fire. As a general rule, they should be placed at least 2 m above floor
level and as close to this height as possible. In schemes where provision is
planned for smoke layering at ceiling level (creating a smoke reservoir),
consultation with the fire service is advisable and consideration should be given
to mounting the luminaires below this zone by using, for example, pendant
luminaires. These luminaires, however, should be at least 2.2 m above the floor
level.
Note that the positions of the escape luminaires can, by themselves, give
the first indication of the escape route.
Escape luminaires should therefore be sited at, or near, positions where it
is necessary to emphasise potential hazards on the route or the location of safety
equipment. ‘Near’ is taken to be within 2 m measured horizontally. The
illuminance on the escape route at these positions should be at least 1 lx. If these
positions are not on the escape route or in an escape area, they should be
illuminated to at least 5 lx on the floor.
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5.20.7.1 Escape route lighting
See Table 5.13 and Figure 5.37. Escape routes must be clearly defined and
permanently unobstructed.
Table 5.13 Requirements for escape route lighting
Item
Value
Route size
Design illuminance:
— on centre line
≤ 30 m long, up to 2 m wide (each 2 m wide strip if route is wider)
— on centre band
Diversity
Disability glare
0·5 lx
Fig. 5.37
1 lx
0·5 lx
1m
2m
Escape route lighting
5.20.7.2 Anti-panic (escape
area) lighting
Response time
Minimum duration
Colour rendering
Minimum design value of 1 lx, on the floor along the centre line of
the route
Minimum design value 0.5 lx, on the floor of the centre band (i.e. at
least 50% of the route width
Illuminance on centre line < 40 (max./min.)
Intensity limits: level routes from γ = 60° to 90° at non-level routes at
all angles (γ) in the lower hemisphere
Design value within 5 s of supply failing
1 hour
Lamp Ra ≥ 40
See Tables 5.14 to 5.16 and Figures 5.38 and 5.39. These are open or reconfigurable areas including teaching spaces, sports/assembly/examination halls
and cafeteria.
It should be noted that there have been changes to the law governing fire
safety in a number of countries. In the UK, the Regulatory Reform (Fire Safety)
Order 2005(56) makes it the legal responsibility of building designers and
owners/occupiers to risk-assess their premises for fire safety. This risk
assessment would include emergency lighting for all areas, but in particular it
should be noted that areas smaller than 60 m2, but which may be open to the
public after dark, may require anti-panic emergency lighting. Recent practice in
schools has been to suggest one luminaire near the exit door providing only
partial illuminance to the room; this is not acceptable.
0·5 lx
0·5 m
Fig. 5.38
0·5 m
Escape area lighting
Fig. 5.39
Emergency task spotlighting
Table 5.14 Requirements for escape area lighting
Item
Value
Area size
Generally ≤ 60 m2 except in places of public assembly or where a
sufficient risk is identified
Minimum design value 0.5 lx on empty floor excluding 0.5 m wide
perimeter band
< 40 (max./min.)
Intensity limits: level routes from γ = 60° to 90°
50% design value in 5 s and 100% design value in 60 s
1 hour
Lamp Ra ≥ 40
Design illuminance
Diversity
Disability glare
Response time
Minimum duration
Colour rendering
Lighting for particular applications
77
Table 5.15 Requirements for lighting in fixed seated areas (i.e. areas in auditoria, sports
halls, conference rooms, lecture theatres having fixed seating)
Item
Value
Area size
Design illuminance
≤ 60 m2
Minimum design value of 0.1 lx on a plane 1 m above floor/pitch line
over seated areas; gangways should be treated as clearly defined
routes
< 40 (max./min.)
Intensity limits: level routes from γ = 60° to 90°
Design value in 5 s
1 hour
Lamp Ra ≥ 40
Diversity
Disability glare
Response time
Minimum duration
Colour rendering
Table 5.16 Requirements for lighting in high risk task areas (i.e. area where hazardous
activity occurs that is to be made safe or terminated or where people may pass by)
Fig. 5.40
Fixed seating area table
Item
Value
Area size
Design illuminance
As defined by task size, location and plane
Minimum 10% of maintained illuminance on the reference plane but
at least 15 lx
> 0.1 (min./average)
Intensity limits: level routes from γ = 60° to 90°
Design value in 5 s or faster if the risk requires it
Period for which the risk to people exists
Lamp Ra ≥ 40
Uniformity
Disability glare
Response time
Duration
Colour rendering
5.20.8 Installation, testing
and maintenance
The success of an emergency lighting system depends not only on the design,
planning and selection of the correct equipment, but also on the satisfactory
installation and maintenance of the equipment throughout its service life. It is
vital that the designer specifies equipment that is fit for the purpose.
Consideration should be given to the choice of products so that they are
serviceable when installed and, if installed in places where access for
maintenance will be restricted, will require virtually no servicing during their
product life. Regular maintenance, servicing and testing of the emergency
lighting installation is very important if it is to be operative when the need
arises.
The emergency lighting system should be installed as instructed by the
designer of the scheme and also in accordance with the equipment
manufacturer’s instructions. The designer usually provides a schedule of
installation, including scheme plans and wiring/piping drawings in which the
location of equipment, placing of protection devices and the choice and routing
of wiring/piping are set out. The schedule or drawings may also give the
sequence of fixing and connections, particularly of complex systems, that the
installer should follow. All such schedules and drawings should be added to the
log book on completion of the installation. These should be updated with
information of all scheme modifications made during the life of the installation.
Maintenance and servicing of the installation should be made regularly.
This work should be carried out by a competent person*, appointed by the
owner/occupier of the premises. The designer should provide a maintenance
schedule that lists and gives details of replacement luminaire components such
as lamp type, battery, fuses, cleaning and topping-up fluids.
Caution should be exercised in servicing, as unenergised circuits may
suddenly become energised automatically. Prime movers and generators will
almost always be started without warning in an emergency or auto test, since a
sensor remote from the plant enclosure initiates the sequence of operations.
* A competent person is someone who has the necessary knowledge, training,
experience and abilities to carry out the work (MSLL or equivalent qualification).
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Lighting Guide 5: Lighting for education
5.20.9 Luminaires
The luminaires must be suitable for the environmental conditions in which they
are expected to function. Luminaires and signs should be cleaned at regular
intervals that may coincide with the time of inspection. Any defects noted
should be recorded in the log book and rectified as soon as possible. The
cleaning interval is dependent on the atmospheric dirt in the installation.
Serviceable components should be replaced by an approved part at the end of the
recommended component service life.
Self-luminous signs, such as a tritium-activated phosphor-coated signs,
should be replaced at the specified end of service life. Note that these signs
contain residual radioactive material and their disposal must be carried out by
an authorised contractor.
Photoluminescent signs must be placed such that they are externally lit
at all times to ensure that the photo luminescent material is fully charged at all
times.
5.20.10 Service schedule
Inspection and maintenance should be carried out in accordance with a
systematic schedule. A typical planned inspection/servicing schedule is as
follows:
—
Check that defects recorded in the log book have been corrected.
—
Clean the exterior of luminaires and signs.
—
Check correct operation of luminaires and internally
illuminated signs by operating the test facility.
—
Check correct operation of engine driven generator(s) and carry
out the manufacturer’s recommended maintenance.
—
Check fuel tanks and oil and coolant levels and top up as
necessary.
—
Check level of electrolyte in batteries of central battery systems
and generator starter batteries.
—
Check that all indicator lamps are functioning.
—
Record data in the log book.
—
Check egress path to determine whether architectural and
furniture changes have rendered the emergency lighting system
ineffective.
—
Check egress path for obstructions that hinder escape during an
emergency.
Instructions issued by manufacturers should also be observed and added
to the service schedule.
Routine inspection and testing should be carried out at the intervals
specified below. Records should be kept of the tests and the results obtained.
Where self-testing or remote testing features are being used, those responsible
for emergency lighting systems should verify that the tests have been conducted
on schedule and have given satisfactory results. Details of routine testing are
given in BS EN 50172(61).
5.20.11 Self-testing and
remote testing
systems
An increasing trend is for emergency lighting to incorporate some form of selftesting facility, or for the luminaires to incorporate a remote monitoring feature.
The electrical test should verify that any self-testing system performs as
intended, and without impairing the integrity of the lighting design. Where selftesting or remote monitoring systems are used as the basis of compliance with
section 12 of BS 5266-1(46), visual inspection of the installed equipment should
be carried out at least annually to verify that it is in good mechanical condition.
BS EN 62034(62) gives details of automatic test systems for battery powered
emergency escape lighting.
Lighting for particular applications
79
5.20.11.1
Daily
It should be verified that the charging supply to the central battery systems is
indicating normal operation. The emergency lighting record log book or
monitoring system should be checked in order that recorded faults may be
rectified.
5.20.11.2
Monthly
A short-duration test should be performed, by simulating a failure of the general
lighting power supply, to verify that all emergency luminaires are operating.
This applies for both self-contained and centrally supplied systems.
The duration of the function test should be as brief as possible, so as not
to discharge batteries unduly or damage the lamps. Engine-driven generators
should be checked for automatic starting and to ensure that they energise the
emergency lighting system correctly.
5.20.11.3
Annually
A full duration test of all systems should be performed, to verify that the
emergency lighting provides its design output for the full design duration.
The duration test should be arranged to occur at a point in time where the
time needed to recharge batteries has the least impact on the occupation of the
building. The signs and luminaires are cleaned if required.
5.20.12 Initial inspection
certificate
A model certificate can be found in BS 5266-1(46).
5.20.12.1
Maintenance
schedule
A maintenance schedule should be prepared as indicated in the service schedule.
5.20.12.2
Log book
Record keeping is an important aspect of maintenance and recording the system
condition. A log book should be kept on the premises in the care of a competent
person appointed by the owner/occupier of the premises and should be readily
available for examination by any duly authorised person. The log book should
contain the following information:
—
date of any completion certificate, including any certificate
relating to alterations
—
a complete set of plans and emergency lighting layouts for the
building; a full set of schematics will be required where central
battery and generator systems are employed
—
a schedule of plant and equipment requiring maintenance,
including information regarding the frequency of testing
—
instructions that highlight planned maintenance tasks and give
guidance on the execution of these tasks
—
a schedule of recording the outcome of all maintenance
inspections and tests carried out, defects and remedial action
—
manufacturers’ installation and instruction manuals for each
individual item of the system, and
—
a schedule detailing the quantity of each spare component (e.g.
lamp, battery, fusing) to be stored on site to enable quick
replacement of failed components; contact details for each
manufacturer should also be included.
Further guidance can be found in BS 5266(46), BS EN 1838(60) and ISO
30061/CIE S 020(63).
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Lighting Guide 5: Lighting for education
6
Checklist
for lighting
design
The designer should check systematically that all the factors relevant to the
design of the lighting installation have been taken into account. In the following
checklist the headings below indicate the areas to be considered and the most
commonly occurring questions. In any specific situation there may be other
questions which need to be considered.
6.1
Task/activity
lighting
(a)
(b)
(c)
(d)
Objectives:
—
Safety requirements: What hazards need to be seen clearly? What
form of emergency lighting is needed? Is a stroboscopic effect
likely?
—
Task requirements: Where are the tasks to be performed in the
interior? What planes do they occupy? What aspects of lighting
are important to the performance of these tasks? Are optical aids
necessary?
—
Appearance: What impression is the lighting required to create?
Constraints:
—
Statutory: Are there any statutory requirements that are relevant
to the lighting installation?
—
Financial: What is the budget available, and what is the relative
importance of capital and running costs including maintenance?
—
Physical: Is a hostile or hazardous environment present? Are
high or low ambient temperatures likely to occur? Is noise from
control gear likely to be a problem? Are mounting positions
restricted, and is there a limit on luminaire size?
—
Historical: Is the choice of equipment restricted by the need to
make the installation compatible with existing installations?
Specification:
—
Source of recommendations: What is the source of the lighting
recommendations used? How authoritative is this source?
—
Form of recommendations: Have all the relevant lighting variables
been considered, e.g. design maintained illuminance,
uniformity, illuminance ratios, surface reflectances and colours,
light source colour, colour rendering group, limiting glare index,
veiling reflections?
—
Qualitative requirements: Have the aspects of the design which
cannot be quantified been carefully considered?
General planning:
—
Daylight and electric lighting: What is the relationship between
these forms of lighting? Is it possible or desirable to provide a
control system to match the electric lighting to the daylight
available?
—
Protection from solar glare and heat gain: Are the windows
designed to limit the effects of solar glare and heat gain on the
occupants of the building? Do the window walls have suitable
reflectance?
—
Choice of electric lighting system: Is general, localised or local
lighting for task or display most appropriate for the situation?
Does obstruction make some form of local lighting necessary?
—
Choice of lamp and luminaire: Does the light source have the
required lumen output, luminous efficacy, colour properties,
lumen maintenance, life, run-up and re-strike properties? Is the
proposed lamp and luminaire package suitable for the
application? Is air handling heat recovery appropriate? Will the
luminaire be safe in the environmental conditions? Will it
withstand the environmental conditions? Does it have suitable
Checklist for lighting design
81
maintenance characteristic and mounting facilities? Does it
conform to BS 4533(64)/BS EN 60598-1(65) or other appropriate
standard? Does the luminaire have an appropriate appearance
and will it enable the desired effect to be created? Are reliable
photometric data available?
(e)
6.2
Lighting and
energy
efficiency
—
Maintenance: Has a maintenance schedule been agreed? Has a
realistic maintenance factor been estimated based on the agreed
schedule or, if not, have the assumptions used to derive the
maintenance factor been clearly recorded? Is the equipment
resistant to dirt deposition? Can the equipment be easily
maintained, is the equipment easily accessible, and will
replacement parts be readily available?
—
Control systems: Are control systems for matching the operation
of the lighting to the availability of daylight and the pattern of
occupancy appropriate? Is a dimming facility desirable? Have
manual switches or local override facilities been provided, are
they easily accessible and is their relationship to the lighting
installation understandable?
—
Interactions: How will the lighting installation influence other
building services? Is it worth recovering the heat produced by
the lamps? If so, have the air flow rates been checked in relation
to the operating efficacy of the lamps?
Detailed planning:
—
Layout: Is the layout of the installation consistent with the
objectives and the physical constraints? Has allowance been
made for the effects of obstruction by building structure, other
services, machinery and furniture? Has the possibility of
undesirable high luminance reflections from specular surfaces
been considered? Does the layout conform to the spacing-toheight ratio criteria?
—
Mounting and electrical supply: How are the luminaires to be fixed
to the building? What system of electricity supply is to be used?
Does the electrical installation comply with the latest edition
(including any subsequent amendments) of BS 7671:
Requirements for electrical installations. IEE Wiring Regulations.
Seventeenth edition(66)?
—
Calculations: Have the design maintained illuminance and
variation been calculated for appropriate planes? Has an
acceptable maintenance programme been specified? Have the
most suitable calculation methods been used? Has the glare
rating been calculated? Have up-to-date and accurate lamp and
luminaire through-life photometric data been used?
—
Verification: Does the proposed installation meet the
specification of lighting conditions? Is it within the financial
budget? Is the power density within the recommended range?
Does the installation fulfil the design objectives?
A lighting installation should meet the lighting requirements of a particular
space in an energy efficient manner. An estimation of the energy requirements
of a lighting installation needs to be made according to BS EN 15193: Energy
performance of buildings. Energy requirements for lighting(22). It gives a methodology
for a numeric indicator of energy performance of buildings. This indicator can
be used for single rooms on a comparative basis only, as the benchmark values
given in BS EN 15193 are intended for complete buildings.
It is important not to compromise the visual aspects of a lighting
installation simply to reduce energy consumption. Light levels as set in BS EN
12464-1(44) are minimum average illuminance values, and need to be obtained.
Therefore, to achieve the required energy performance, consideration of
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Lighting Guide 5: Lighting for education
appropriate lighting systems, equipment, controls and the use of available
daylight is essential.
Energy efficiency calculations may also be required to prove compliance
with local building regulations, such as Building Regulations Part L(18) for
England and Wales.
An energy efficiency checklist would include questions such as:
7
Lighting
maintenance
—
Does the lighting design exceed 55 luminaire lumens per circuit
watt for the teaching, office, industrial and storage spaces?
—
Do areas other than these also exceed 55 luminaire lumens per
circuit watt, including display lighting where practical?
—
Are full lighting controls for daylight harvesting installed in all
rooms that receive daylight?
—
Is manual on/off with absence override detection fitted to all
interior luminaires?
—
Are lighting controls commissioned appropriately to the
patterns or daylight and use?
—
Does the exterior lighting comply to a minimum of 80 lm/W for
colour rendering light sources Ra < 60 and with 70 lm/W for
light sources with Ra > 60?
—
Are suitable daylight and time controls fitted to all exterior
lighting?
—
Is high frequency (HF) gear used for all luminaires?
—
Where dimming gear is fitted do the ballasts use > 0.5 W when
no light is emitted? (From the year 2017, any new luminaire
ballasts should use zero power when no light is emitted).
In both lecture and conference spaces it is essential for the lighting equipment
to be properly maintained. Lamps that have failed or are flickering not only fail
in their function, but convey the impression to audience and lecturer alike that
nobody cares. It is important that lamps that have failed be replaced promptly,
and with lamps of precisely the same type and colour.
In raked lecture theatres, access to the luminaires is often difficult from
below. This is a point that the designer must bear in mind. It is strongly
advisable for a group replacement scheme to be used, in which all of the lamps
are replaced at set intervals. The reader is referred to the SLL Code for Lighting(8)
on the maintenance of lighting systems.
Other items such as blackout blinds, projection screens and lighting
controls suffer damage relatively frequently. Any damage of this kind should be
made good promptly. It can largely be avoided by using simple controls with
clear instructions adjacent to the item concerned and using equipment of
sufficiently robust construction to withstand the onslaughts of daily use.
During the life of a lighting installation the amount of light it produces
will diminish. This reduction is caused mainly by dirt building-up on the
lamps, the luminaires or, in the case of natural lighting, on the windows. There
will also be a reduction caused by dirt build-up on the internal surfaces of the
rooms, diminishing their reflectance. Lamp light output will also reduce with
ageing, some light sources losing more output than others.
These reductions in lighting levels will need to be minimised if energy
and money are not to be wasted, and to achieve this it is important to pay
attention at the design stage to the proper maintenance of the lighting
installation and of the building itself. This aspect should be discussed in
advance with the users of the building to ensure that they are aware of the
proposed maintenance strategy and its implications and obtain their cooperation.
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Lighting Guide 5: Lighting for education
appropriate lighting systems, equipment, controls and the use of available
daylight is essential.
Energy efficiency calculations may also be required to prove compliance
with local building regulations, such as Building Regulations Part L(18) for
England and Wales.
An energy efficiency checklist would include questions such as:
7
Lighting
maintenance
—
Does the lighting design exceed 55 luminaire lumens per circuit
watt for the teaching, office, industrial and storage spaces?
—
Do areas other than these also exceed 55 luminaire lumens per
circuit watt, including display lighting where practical?
—
Are full lighting controls for daylight harvesting installed in all
rooms that receive daylight?
—
Is manual on/off with absence override detection fitted to all
interior luminaires?
—
Are lighting controls commissioned appropriately to the
patterns or daylight and use?
—
Does the exterior lighting comply to a minimum of 80 lm/W for
colour rendering light sources Ra < 60 and with 70 lm/W for
light sources with Ra > 60?
—
Are suitable daylight and time controls fitted to all exterior
lighting?
—
Is high frequency (HF) gear used for all luminaires?
—
Where dimming gear is fitted do the ballasts use > 0.5 W when
no light is emitted? (From the year 2017, any new luminaire
ballasts should use zero power when no light is emitted).
In both lecture and conference spaces it is essential for the lighting equipment
to be properly maintained. Lamps that have failed or are flickering not only fail
in their function, but convey the impression to audience and lecturer alike that
nobody cares. It is important that lamps that have failed be replaced promptly,
and with lamps of precisely the same type and colour.
In raked lecture theatres, access to the luminaires is often difficult from
below. This is a point that the designer must bear in mind. It is strongly
advisable for a group replacement scheme to be used, in which all of the lamps
are replaced at set intervals. The reader is referred to the SLL Code for Lighting(8)
on the maintenance of lighting systems.
Other items such as blackout blinds, projection screens and lighting
controls suffer damage relatively frequently. Any damage of this kind should be
made good promptly. It can largely be avoided by using simple controls with
clear instructions adjacent to the item concerned and using equipment of
sufficiently robust construction to withstand the onslaughts of daily use.
During the life of a lighting installation the amount of light it produces
will diminish. This reduction is caused mainly by dirt building-up on the
lamps, the luminaires or, in the case of natural lighting, on the windows. There
will also be a reduction caused by dirt build-up on the internal surfaces of the
rooms, diminishing their reflectance. Lamp light output will also reduce with
ageing, some light sources losing more output than others.
These reductions in lighting levels will need to be minimised if energy
and money are not to be wasted, and to achieve this it is important to pay
attention at the design stage to the proper maintenance of the lighting
installation and of the building itself. This aspect should be discussed in
advance with the users of the building to ensure that they are aware of the
proposed maintenance strategy and its implications and obtain their cooperation.
Management of lecture and conference spaces
83
The designer should pay specific attention to the life and lumen
prediction graphs for each light source, especially when considering LEDs.
Across the range of light sources there are a number of different life measures
for instance that vary from 90% lumen output to 50% failure of a batch of lamps.
For LEDs, until there is international agreement on this fast developing
technology, the designer should consult Guidelines for the specification of LED
lighting products(45), which has been produced by a joint committee representing
the SLL, the Institution of Lighting Engineers, the Lighting Industry
Federation, the Professional Lighting Designers’ Association, the International
Association of Lighting Designers, and the Highway Electrical Manufacturers
and Suppliers Association.
8
Management
of lecture
and
conference
spaces
For the purposes of managing lecture theatres there are three categories:
(a)
those supposedly devoted to a single subject or single
department of an educational institution, e.g. the ‘nuclear
physics’ theatre
(b)
those in common use by a wide variety of departments in an
educational institution; often very heavily used
(c)
those in research institutes, professional institutions, museums,
galleries and so on; usually relatively lightly used.
In practice, all lecture theatres are on occasions used for purposes other
than those intended, sometimes on a hire basis.
8.1
Visual clutter
Fig. 8.1
A large lecture theatre
kept clear of clutter
though the wall behind
the lecture station is
relatively busy in design
terms (photograph courtesy
of Thorn Lighting)
Mention has already been made in section 5.3.3.3 of the need to keep lecture
rooms free of visual clutter, which means keeping them free of unwanted
paraphernalia that serves only to distract the attention of the audience from the
speaker. It is an essential part of managing a lecture theatre or conference room
to see that unwanted paraphernalia is kept out, see Figure 8.1 below.
Lecture theatres of category (a) are particularly prone to these intrusions;
wall charts, glass cased specimens and glazed portraits of the great men of the
subject serve to distract rather than inspire. Such items should only be
permanently displayed if there is a real need to refer to them frequently, e.g. the
periodic table in a chemistry lecture theatre.
The absence of visual clutter is also welcome in lecture rooms and
classrooms, where it can be equally distracting.
Management of lecture and conference spaces
83
The designer should pay specific attention to the life and lumen
prediction graphs for each light source, especially when considering LEDs.
Across the range of light sources there are a number of different life measures
for instance that vary from 90% lumen output to 50% failure of a batch of lamps.
For LEDs, until there is international agreement on this fast developing
technology, the designer should consult Guidelines for the specification of LED
lighting products(45), which has been produced by a joint committee representing
the SLL, the Institution of Lighting Engineers, the Lighting Industry
Federation, the Professional Lighting Designers’ Association, the International
Association of Lighting Designers, and the Highway Electrical Manufacturers
and Suppliers Association.
8
Management
of lecture
and
conference
spaces
For the purposes of managing lecture theatres there are three categories:
(a)
those supposedly devoted to a single subject or single
department of an educational institution, e.g. the ‘nuclear
physics’ theatre
(b)
those in common use by a wide variety of departments in an
educational institution; often very heavily used
(c)
those in research institutes, professional institutions, museums,
galleries and so on; usually relatively lightly used.
In practice, all lecture theatres are on occasions used for purposes other
than those intended, sometimes on a hire basis.
8.1
Visual clutter
Fig. 8.1
A large lecture theatre
kept clear of clutter
though the wall behind
the lecture station is
relatively busy in design
terms (photograph courtesy
of Thorn Lighting)
Mention has already been made in section 5.3.3.3 of the need to keep lecture
rooms free of visual clutter, which means keeping them free of unwanted
paraphernalia that serves only to distract the attention of the audience from the
speaker. It is an essential part of managing a lecture theatre or conference room
to see that unwanted paraphernalia is kept out, see Figure 8.1 below.
Lecture theatres of category (a) are particularly prone to these intrusions;
wall charts, glass cased specimens and glazed portraits of the great men of the
subject serve to distract rather than inspire. Such items should only be
permanently displayed if there is a real need to refer to them frequently, e.g. the
periodic table in a chemistry lecture theatre.
The absence of visual clutter is also welcome in lecture rooms and
classrooms, where it can be equally distracting.
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Lighting Guide 5: Lighting for education
8.2
Lecture
attendants
The term ‘lecture attendant’ refers to those individuals who actually assist in the
performance of lectures. The job of such lecture attendants is to see that the
lecturer’s needs are fulfilled, e.g. that the lights are raised or lowered at the right
time, the sound is correct and so on. To do this, it is necessary for the attendant
to give undivided attention to assisting the lecturer and to avoid distraction.
Where there is a control booth or room for the lecture assistant, care
should be taken that stray light and sound do not distract the audience from the
presentation and that the assistant, who may be visible, does not cause distraction to the lecturer.
To limit light nuisance, the assistant should be provided with a carefully
shielded task light. Care should be taken to see that light from the audience area
does not cause glare to the assistant, either on their equipment or within their
view field of view of the lecture theatre.
8.3
Communication
between
lecturer and
projectionist
or projector
In the majority of lectures in which images are shown, a laptop computer under
the direct control of the lecturer is used. In these cases often the lecturer has
complete control of the room and the controls available to them should be clearly
marked, sufficiently distinct to be visible in near-darkness. The controls
available to the lecturer should also include an on/off switch for any projector, as
it often happens that there are long periods when projection is not required and
the fan noise may distract and annoy the audience.
Lighting controls are similar; it is best if they can be operated directly by
the lecturer, but again the controls must be simple and clearly marked. Some
duplicate controls for the lights should be provided near the main entrance
door(s).
There are occasions when control of the projection, sound and lighting
has to be in the hands of an attendant, for example when a large array of
demonstrations is presented or for a full day’s conference containing many
different presenters and media. In this case the lecturer should have a speaker’s
screen showing an image and perhaps speaker’s notes of the slide that the
audience is currently viewing. There should also be a controller for advancing
the presentation, though commonly these are now wireless.
8.4
Projection
rooms and
booths
The traditional projection room adjacent to a lecture room is nowadays used
more often as a control room than a projection room. Experience shows that such
a room is essential in any lecture theatre seating more than 150. Besides housing
the projection equipment, it may also be needed to house sound amplifying
equipment, lighting controls, image recording and projection equipment, and
possibly controls for the air conditioning system. A projection booth within a
lecture theatre is not recommended unless situated where there is no risk of
distraction or difficulty of access once an audience is seated.
8.5
Preparation
and equipment
rooms
The multiplicity of audio/visual aid techniques of recent years have now
converged normally to a single projector and sound system with, in some cases,
an interactive screen. The need for separate lockable equipment rooms is less
than before but some form of storage should be provided for the relevant cables
and power extensions often required by visiting presenters.
In large lecture theatres there should ideally be a large equipment room
adjacent to and on the same floor as the demonstration area, which can be used
to house items needed for only part of the presentation. The lighting in these
rooms needs to be sufficient for safe set-up and removal of these items, which
may include fine detail tasks, but should be suitably shielded from the main
space so as to limit distraction to the audience. This can normally be achieved
either through lighting controls in the equipment room, or by a suitable lobby
between rooms.
Lighting control sensors in these rooms should be positioned carefully to
detect fine movement possibly shadowed by the body of the technician.
Lighting costs
85
8.6
Problems for
visiting
lecturers
The main problem facing the visiting lecturer is unfamiliarity with the lighting
controls, and seeing that the audio/visual aids chosen will work satisfactorily on
the apparatus provided, for instance that the presenter’s laptop computer
connects to the projector.
Reference has already been made to the necessity for lighting and
projector controls to be clearly marked. They should be few in number and
should be grouped separately from other controls. A control panel resembling a
complex computer interface does nothing to ease the lecturer’s task unless it is
blatant in its simplicity of operation.
8.7
Lectures
involving
demonstrations
Access to the theatre/room from cars or vans is required. Demonstration
equipment intended to be seen by large numbers of people must itself be large,
and may obstruct the view of some members of the audience of either the
projection screen or the lecturer. This is particularly the case in lecture rooms
and conference rooms as distinct from raked lecture theatres. To avoid this
problem the presentation area should be devoid of any fixed furniture, using
loose tables or benches combined with the provision for additional theatrical
style lighting where required.
9
Lighting
costs
9.1
General
The cost of lighting can be divided into three parts: (a) the capital cost of the
equipment, including its installation, (b) the running costs, which include both
maintenance and the cost of energy, and (c) the environmental or sustainability
costs.
It is important that all aspects are considered when the lighting is being
designed. In terms of capital cost, the amount will be small compared to the total
cost of the building and yet lighting has a major effect on its appearance and
operation, and economies need to be considered carefully to ensure that they are
not false economies. Energy and maintenance costs are a continuing burden on
the operation of any educational building and need to be taken into account at
the design stage to ensure that they can be kept at an acceptable level. The
sustainability costs will include items such as recycling and replacement, for
instance the cost of obtaining raw materials, transport and manufacture of
replacement luminaires and that or returning the failed components to a
recycling point and converting them into re-usable materials.
For many buildings, the capital and running cost elements may be borne
by different bodies, which can result in conflict. It is important therefore that
the lighting designer produces a scheme which takes a balanced view of energy
and cost efficiency, considering the true life cycle costs.
9.2
Emergency
lighting
10
Equipment
10.1 Lamps
Emergency lighting, by its very nature, introduces additional running costs.
Even as a safety system it is important to consider the technologies used and
make rational decisions about the life cycle costs. For instance the provision of
traditional 8 W bulkheads for emergency lighting may introduce significant
maintenance and environmental costs in lamp and battery replacement
compared to well designed LED emergency lighting fittings, which have a longer
light source life and use less battery material.
Testing and maintenance of emergency lighting is essential and the
designer should consider carefully the cost to building managers of the testing
and regular maintenance visits necessary. The use of self-test and central test
emergency products may negate the need to provide staff to test emergency
systems and may regulate the number of maintenance visits to just those when
components are reported as faulty.
Where such self-test systems are used the provision of training and
operation manuals that are simple to understand is essential.
Characteristics of the main lamp types are summarised in Table 10.1.
Lighting costs
85
8.6
Problems for
visiting
lecturers
The main problem facing the visiting lecturer is unfamiliarity with the lighting
controls, and seeing that the audio/visual aids chosen will work satisfactorily on
the apparatus provided, for instance that the presenter’s laptop computer
connects to the projector.
Reference has already been made to the necessity for lighting and
projector controls to be clearly marked. They should be few in number and
should be grouped separately from other controls. A control panel resembling a
complex computer interface does nothing to ease the lecturer’s task unless it is
blatant in its simplicity of operation.
8.7
Lectures
involving
demonstrations
Access to the theatre/room from cars or vans is required. Demonstration
equipment intended to be seen by large numbers of people must itself be large,
and may obstruct the view of some members of the audience of either the
projection screen or the lecturer. This is particularly the case in lecture rooms
and conference rooms as distinct from raked lecture theatres. To avoid this
problem the presentation area should be devoid of any fixed furniture, using
loose tables or benches combined with the provision for additional theatrical
style lighting where required.
9
Lighting
costs
9.1
General
The cost of lighting can be divided into three parts: (a) the capital cost of the
equipment, including its installation, (b) the running costs, which include both
maintenance and the cost of energy, and (c) the environmental or sustainability
costs.
It is important that all aspects are considered when the lighting is being
designed. In terms of capital cost, the amount will be small compared to the total
cost of the building and yet lighting has a major effect on its appearance and
operation, and economies need to be considered carefully to ensure that they are
not false economies. Energy and maintenance costs are a continuing burden on
the operation of any educational building and need to be taken into account at
the design stage to ensure that they can be kept at an acceptable level. The
sustainability costs will include items such as recycling and replacement, for
instance the cost of obtaining raw materials, transport and manufacture of
replacement luminaires and that or returning the failed components to a
recycling point and converting them into re-usable materials.
For many buildings, the capital and running cost elements may be borne
by different bodies, which can result in conflict. It is important therefore that
the lighting designer produces a scheme which takes a balanced view of energy
and cost efficiency, considering the true life cycle costs.
9.2
Emergency
lighting
10
Equipment
10.1 Lamps
Emergency lighting, by its very nature, introduces additional running costs.
Even as a safety system it is important to consider the technologies used and
make rational decisions about the life cycle costs. For instance the provision of
traditional 8 W bulkheads for emergency lighting may introduce significant
maintenance and environmental costs in lamp and battery replacement
compared to well designed LED emergency lighting fittings, which have a longer
light source life and use less battery material.
Testing and maintenance of emergency lighting is essential and the
designer should consider carefully the cost to building managers of the testing
and regular maintenance visits necessary. The use of self-test and central test
emergency products may negate the need to provide staff to test emergency
systems and may regulate the number of maintenance visits to just those when
components are reported as faulty.
Where such self-test systems are used the provision of training and
operation manuals that are simple to understand is essential.
Characteristics of the main lamp types are summarised in Table 10.1.
Lighting costs
85
8.6
Problems for
visiting
lecturers
The main problem facing the visiting lecturer is unfamiliarity with the lighting
controls, and seeing that the audio/visual aids chosen will work satisfactorily on
the apparatus provided, for instance that the presenter’s laptop computer
connects to the projector.
Reference has already been made to the necessity for lighting and
projector controls to be clearly marked. They should be few in number and
should be grouped separately from other controls. A control panel resembling a
complex computer interface does nothing to ease the lecturer’s task unless it is
blatant in its simplicity of operation.
8.7
Lectures
involving
demonstrations
Access to the theatre/room from cars or vans is required. Demonstration
equipment intended to be seen by large numbers of people must itself be large,
and may obstruct the view of some members of the audience of either the
projection screen or the lecturer. This is particularly the case in lecture rooms
and conference rooms as distinct from raked lecture theatres. To avoid this
problem the presentation area should be devoid of any fixed furniture, using
loose tables or benches combined with the provision for additional theatrical
style lighting where required.
9
Lighting
costs
9.1
General
The cost of lighting can be divided into three parts: (a) the capital cost of the
equipment, including its installation, (b) the running costs, which include both
maintenance and the cost of energy, and (c) the environmental or sustainability
costs.
It is important that all aspects are considered when the lighting is being
designed. In terms of capital cost, the amount will be small compared to the total
cost of the building and yet lighting has a major effect on its appearance and
operation, and economies need to be considered carefully to ensure that they are
not false economies. Energy and maintenance costs are a continuing burden on
the operation of any educational building and need to be taken into account at
the design stage to ensure that they can be kept at an acceptable level. The
sustainability costs will include items such as recycling and replacement, for
instance the cost of obtaining raw materials, transport and manufacture of
replacement luminaires and that or returning the failed components to a
recycling point and converting them into re-usable materials.
For many buildings, the capital and running cost elements may be borne
by different bodies, which can result in conflict. It is important therefore that
the lighting designer produces a scheme which takes a balanced view of energy
and cost efficiency, considering the true life cycle costs.
9.2
Emergency
lighting
10
Equipment
10.1 Lamps
Emergency lighting, by its very nature, introduces additional running costs.
Even as a safety system it is important to consider the technologies used and
make rational decisions about the life cycle costs. For instance the provision of
traditional 8 W bulkheads for emergency lighting may introduce significant
maintenance and environmental costs in lamp and battery replacement
compared to well designed LED emergency lighting fittings, which have a longer
light source life and use less battery material.
Testing and maintenance of emergency lighting is essential and the
designer should consider carefully the cost to building managers of the testing
and regular maintenance visits necessary. The use of self-test and central test
emergency products may negate the need to provide staff to test emergency
systems and may regulate the number of maintenance visits to just those when
components are reported as faulty.
Where such self-test systems are used the provision of training and
operation manuals that are simple to understand is essential.
Characteristics of the main lamp types are summarised in Table 10.1.
86
Table 10.1 Summary of lamp types
Lamp type
Format
Nominal size
Power
range
(W)
Control gear
Efficacy
(lm/W)
Colour
rendering
group
Colour appearance
(K)
Dimming
options
Suitable for central
control system
Linear fluorescent
T16 (T5)
(16 mm diam.)
T16 (T5) miniature
(16 mm diam.)
T26 (T8)
(26 mm diam.)
Various
Various
600–1500 mm
14–80
Electronic
60–95
1A–1B
Yes
Yes
150–530 mm
4–13
Electronic/magnetic
35–65
3
2700–4000
6000 (limited options)
3500
No
No
600–1800 mm
18–70
Electronic/magnetic
55–95
1A–1B
Yes
Yes
Various
Various
16–120
18–70
Electronic
Electronic
64–88
64–76
1B
1B
3000–4000
6000 (limited options)
3000–4000
3000–4000
Yes
Limited
Yes
Yes
Various
20–2000
Electronic/magnetic
70–115
1A–2B
Very limited
Yes; not suitable for
frequent switching
Linear fluorescent
Linear fluorescent
Compact fluorescent
Compact fluorescent
amalgam
Metal halide*
Various
3000–4000
6000 (limited options)
50–1000
Electronic/magnetic
65–125
4
2000
Very limited
No
(up to 150 for
600/1000 W
lamps)
* Metal halide and SON lamps can take several minutes to run up to full output and, immediately after being switched off, can take several minutes to re-strike. Some low wattage options can be run at
reduced output on special electronic control gear but dimming range is limited and colour variations can occur.
Lighting Guide 5: Lighting for education
Single ended
tubular, double
ended and
reflector
High pressure sodium* SON tubular
Equipment
87
10.2 Control gear
A wide range of lamps require control gear of some kind to ensure correct
running and starting of the lamp. This gear in various lamps controls either the
voltage or the current and may itself operate at differing voltages and
frequencies.
10.2.1.1 General principles
Where available the designer should specify the most appropriate and efficient
control gear for all lighting. In general this would imply high frequency (HF) or
electronic control gear for all luminaires. Control gear should comply with the
minimum targets set by the Energy-using Products Directive(17) for lighting.
10.2.1.2 Electromagnetic
control gear for
fluorescent light
sources
Generally electromagnetic gear used in fluorescent circuits is considered
inefficient when compared to high frequency circuits, and causes user
discomfort through 100 Hz flicker. In all teaching/learning buildings high
frequency control gear should be used as standard except where a suitable case
can be made on health and safety grounds or if alternative technologies are
developed that remove the problem of flicker and improve the sustainable case
for this technology.
10.2.1.3 Electronic control gear
for fluorescent light
sources
Operating fluorescent lamps at high frequency has a number of advantages and
most modern control gear is now of this type. Most electronic ballasts for
fluorescent lamps are integrated into a single package that performs a number of
functions including limiting the amount of harmonic distortion, controlling the
amount of radio frequency interference, and protecting the ballast against high
voltage mains peaks. Where high frequency ballasts are used with in-built
protection fuses there will be no need to fit additional fused terminal blocks.
In some ballasts it is possible to dim the lamp by use of an additional
control signal, either analogue or digital signals. The designer should look
carefully at the features and benefits that the various types offer, weighing up the
true cost or energy implications. For instance, while it may be beneficial to dim
rather than switch a luminaire in response to daylight, offering considerable
energy savings in some installations, the parasitic power absorbed by the ballast
and control system must be taken into account.
10.2.1.4 Electronic gear for HID
light sources
There are many types of high intensity discharge (HID) lamp, with different
electrical requirements and a limited range of frequencies in which they can be
operated. Also many lamp types do not show a significant gain in efficiency
when operated on high frequencies. However, it is possible to gain a number of
benefits from electronic gear for HID lamps. These include increased lamp life,
elimination of visible flicker, better system efficacy, less sensitivity to
fluctuations in mains voltage or temperature and the possibility of dimming
with some lamp types.
Not all these benefits are possible for all lamp types and all control gear
combinations. However, the availability and quality of electronic gear available
for HID lamps is rapidly increasing.
10.2.1.5 Transformers for low
voltage light sources
Many tungsten–halogen lamps are designed to run on low voltages the most
common of which is 12 volts. Thus they need a device to reduce the supply
voltage. The traditional way to do this was by using a transformer.
As well as reducing the voltage, the transformer also isolates the lamp
supply from the mains. This means that even under a fault condition the voltage
in the secondary circuit will not rise significantly above the nominal output
voltage and so it will always be safe to touch the conductors on the low voltage
side. In all educational buildings transformers for halogen lamps should be of
the electronic type with a minimum circuit efficacy of 22 lumens per circuit watt
(lm/W) for a ‘pass’ rating, 29 lm/W for ‘good’ and 36 lm/W for ‘excellent’.
10.2.2 Drivers for LEDs
LEDs
need to be run at a controlled current to ensure proper operation. To
provide this drivers are used. Most drivers take mains power and provide a
88
Lighting Guide 5: Lighting for education
constant current output. However, it is possible to control some drivers so that
output current is varied so that the LED may be dimmed. In more complex
systems it is possible to dim three separate channels separately, so that when red,
green and blue LEDs are used together it is possible to make colour changes.
Most LED drivers can maintain their constant current output over a range of
voltages so it is often possible to connect a number of LEDs in series on one
driver. The designer should take care to avoid flicker inherent in cheaper LED
drivers. For LED circuits to be considered efficient they should meet or exceed
the same efficacy targets for other lighting.
10.3 Lighting
controls
Wherever practical lighting controls should be included to provide scene setting
functionality where required and energy saving where users are unlikely to
switch off lighting when not required. In daylit spaces lighting should be
circuited according to the amount of daylight likely to occur in the area lit by
the luminaire. Luminaires in daylight zones should then be switched, according
to the daylight present. Preference must be given to systems that dim according
to daylight and hence also provide for constant illuminance control from the
luminaires.
10.3.1 Options for control
There are a number of factors that need to be considered in any control system;
these are the inputs to system, how the system controls the lighting equipment
and what is the control process that decides how a particular set of inputs will
impact on the lighting. Thus for a control system to function it must have input
devices such as switches, presence detectors, timers and photocells. Control
processes may consist of a simple wiring network through to a computer-based
control system. The system may control luminaires in a number of ways, from
simply switching them on and off to dimming the lamp and, in more complex
systems, causing movement of spotlights and colour changes.
10.3.2 Input devices
Lighting controls require a number of inputs to make them function, broadly
they are classified as follows.
10.3.2.1 Manual inputs
These vary from simple switches used to turn the lights on though dimmer
switches and remote control units that interface to a control system to lighting
control desks that are used in theatres. The point of these units is to allow people
to control the lighting and care is always needed in the application of such
devices to ensure that users of the system can readily understand the function of
any such control.
10.3.2.2 Presence detectors
Most presence detectors are based on passive infrared (PIR) detectors. However
some devices are based on microwave or ultrasonic technology. PIR devices
monitor changes in the amount of infrared radiation that they are receiving. The
movement of people in a space will be detected by them and this can be signalled
to a control system. Thus if a device detects the presence of a person this can be
used to signal the control system to switch the lights on, but if no persons have
been detected for some time this can be used to signal that the lights can be
turned off.
It is strongly recommended that these detectors, when used in
educational spaces, should be used for absence detection with a manual override
for teaching staff. This enables sufficient flexibility for teaching purposes, but
also offers the maximum energy savings.
In order to achieve an excellent efficiency rating in an educational
building, more than 60% of luminaires need to be controlled for daylight and
absence using controls within the parasitic power limitations set in the Energyusing Products Directive(17).
10.3.2.3 Timers
Most computerised control systems have timers built in so that they can turn the
lighting on or off at particular times. However, there are also a large number of
Equipment
89
time switches available that can turn lamps on and off at given times. Timers for
external lighting are available that change the time at which they operate
throughout the year, so that the lamps are switched at dawn and dusk.
Timers should be carefully considered and only those used that respond
also to ambient conditions or time of year and so offer maximum energy savings.
10.3.2.4 Photocells
There are many different types of photocells used to control lighting. The
simplest to use are those that switch on at one illuminance value and switch off
at another and are often used outdoors for car park, security and amenity
lighting. Some photocells communicate the illuminance value detected to a
central control system, which uses the information to adjust the lighting in
some way. Some photocells are mounted on ceilings with shields around them
so that they only receive light reflected from the working plane; this allows
them to act like luminance meters and, provided the reflectance of the working
plane remains constant, they can be set to provide constant illuminance.
Photocell control should be considered essential for all teaching spaces as
considerable daylight will be available. They should also be fitted to all external
lighting and to lighting elsewhere in the space where daylight is sufficient. As
their use in occupied spaces may lead to nuisance switching the designer should
consider the use of dimming luminaires where this is more appropriate.
10.3.3 Control processes
and systems
In the case of simple control systems these are generally configured as some
form of automated switching in the power supply to a luminaire or group of
luminaires. However, more complex systems are generally configured as a
network of devices including luminaires, sensors and control inputs. In most
systems the devices are physically connected using some form of cabled network
or based on the local area network (LAN).
There are several systems in common use for lighting systems and care
needs to be taken to specify the correct type for each component in the system.
The most common systems offer differing levels of functionality and speed of
response. The designer should consider carefully the needs of the controls
system, for instance the speed of response and number of channels available
would make the DMX512 protocol an obvious choice for theatre, drama and
some conference rooms, whereas DSI or DALI would be more appropriate for
classrooms. In all cases a control strategy needs to be developed and this should
consider primarily the efficiency savings possible and the comfort needs of the
occupants. Too complex a system will often render the system inoperable to all
but the most determined user.
10.3.4 Recommended
minimum controls
provision
The minimum controls provision recommended for various types of space are
given in Table 10.2 below.
10.4 Disposal of
used lighting
equipment
The WEEE Regulations(25) make business users, manufacturers and retailers of
electrical and electronic equipment (EEE) responsible for making sure their
goods do not end up in landfill or incineration, where the toxic chemicals,
metals and associated solders, glues and plastics can cause environmental and
health problems.
Original equipment manufacturers (OEMs) now have cradle-to-grave
responsibility for their electrical products, having to pay for the treatment and
recycling of all affected products. The designer should ensure that any
equipment they specify is suited to recycling and that the producer, who may be
the wholesaler, electrical contractor, importer or OEM, complies with the WEEE
Regulations. The installer who removes old equipment, or purchases new,
should ensure that all obsolete luminaires or other EEE is dealt with accordingly.
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Lighting Guide 5: Lighting for education
Table 10.2 Recommended minimum controls provision
Type of space
Description
Recommended minimum controls
Owned space
A space such as a small room for
one or two people who control
the lighting, e.g. a cellular office
or tutorial room.
Shared space
A multi-occupied area, e.g.
classroom, common room, an
open-plan office or craft area.
Temporarily owned
space
A space where people are
expected to operate the lighting
controls while they are there,
e.g. a lecture or meeting room.
Occasionally visited
space
A space where people generally
stay for a relatively short period
of time when they visit the space,
e.g. a storeroom or toilet.
A space where individual users
require lighting but are not
expected to operate the lighting
controls, e.g. a corridor or atrium.
Manual switch by the door with
absence* override. Separate circuit
for daylight dimming, or switching,
of luminaires close to the window in
daylight spaces.
Manual switch by the door with
absence* override. Separate circuits
for daylight dimming or switching of
luminaires in appropriate zones
according to the amount of daylit
for daylight spaces.
Local manual control with absence*
override. Sensor(s) should be
suitably mounted to pick up the
movement of occupants and
speaker.
Manual on with absence* override.
Presence detection may be
acceptable provided sensors use no
more than 0.5 W.
Time switching, or manual on with
absence* override, or presence
provided individual sensors use no
more than 0.5 W.
Separate circuits for daylight
dimming or switching of luminaires
in appropriate zones according to
the amount of daylight for daylit
spaces.
Time switching, scene setting or
central switching by a responsible
person.
Un-owned space
Managed space
A space where lighting is under
the control of a responsible
person, e.g. a conference room,
theatre or sports hall.
Separate circuits for daylight
dimming or switching of luminaires
in appropriate zones according to
the amount of daylight for daylit
spaces.
* Absence sensors should be circuited such that they switch themselves off and hence use zero
power when the lighting is off.
11
Glossary
The definitions and explanations given in this glossary are intended to help
readers to understand this Lighting Guide. They are based on BS EN 12665:
Light and lighting. Basic terms and criteria for specifying lighting(67), which should be
consulted if more precise definitions are needed.
adaptation
The process by which the state of the visual system is modified by previous and
present exposure to stimuli that may have various luminances, spectral
distributions and angular subtenses.
adjoining spaces
Foyers, ante-rooms, lobbies and corridors immediately adjoining teaching
spaces listed in this Lighting Guide.
chromaticity
The property of a colour stimulus defined by its chromaticity coordinates, or by
its dominant or complementary wavelength and purity taken together.
100
Lighting Guide 5: Lighting for education
Appendix A1: luminance limits and display screen equipment
The following flowcharts offer suggestions to ensure that the luminance is
appropriate to the type of display screen equipment in use, see section 5.10.2.
They use a 95% satisfaction criterion, i.e. 95% of users would not experience
problems with veiling reflections at the luminance limits indicated.
Size of
light source
Brightness of
light source
DSE
type
DSE
polarity
Suggestion
< 200 cd/m2
All
types
All
polarities
OK to use
Negative
Change display polarity or surface finish
Positive
OK to use
Negative
OK to use
Positive
OK to use
Negative
OK to use
Positive
Change display polarity
Negative
Change display polarity or surface finish
Positive
OK to use if LB > 400 cd/m2 or change finish
Negative
OK to use
Positive
OK to use
Negative
Change display polarity
Positive
OK to use
Negative
Change display polarity or surface finish
Positive
OK to use if LB > 700 cd/m2 or change finish
Negative
Change display polarity
Positive
OK to use
Negative
Change display polarity
Positive
OK to use if LB > 600 cd/m2
Negative
Change display polarity or surface finish
Positive
OK to use if LB > 900 cd/m2 or change finish
Negative
Change display polarity
Positive
OK to use if LB > 300 cd/m2
Negative
Change display polarity
Positive
OK to use if LB > 800 cd/m2
Glossy
LCD
200–300
cd/m2
Matt
LCD
Project
IWB
Glossy
LCD
300–500
cd/m2
Matt
LCD
Project
IWB
Angular
diameter 15°
Glossy
LCD
500–1000
cd/m2
Matt
LCD
Project
IWB
Glossy
LCD
1000–1500
cd/m2
Fig. A1.1 Evaluation and correction
of glare in display screen
equipment (DSE) for large
light sources (15° angular
diameter) such as large
windows or atria
Matt
LCD
Project
IWB
Abbreviations and symbols
LB = background luminance on display screen (cd/m2); LCD = liquid crystal display; IWB = interactive white board;
‘Positive’ polarity means dark text on light background; ‘Negative’ polarity means light text on dark background
Appendix A1: luminance limits and display screen equipment
Size of
light source
101
Brightness of
light source
DSE
type
DSE
polarity
Suggestion
< 300 cd/m2
All
types
All
polarities
OK to use
Negative
Change display polarity or surface finish
Positive
OK to use if LB > 200 cd/m2 or change finish
Negative
OK to use
Positive
OK to use
Negative
Change display polarity
Positive
OK to use
Negative
Change display polarity or surface finish
Positive
OK to use if LB > 400 cd/m2 or change finish
Negative
OK to use
Positive
OK to use
Negative
Change display polarity
Positive
OK to use
Negative
Change display polarity or surface finish
Positive
OK to use if LB > 500 cd/m2 or change finish
Negative
OK to use
Positive
OK to use
Negative
Change display polarity
Positive
OK to use
Negative
Change display polarity or surface finish
Positive
OK to use if LB > 700 cd/m2 or change finish
Negative
Change display polarity
Positive
OK to use
Negative
Change display polarity
Positive
OK to use if LB > 500 cd/m2
Glossy
LCD
300–500
cd/m2
Matt
LCD
Project
IWB
Glossy
LCD
500–700
cd/m2
Matt
LCD
Project
IWB
Angular
diameter 10°
Glossy
LCD
700–1000
cd/m2
Matt
LCD
Project
IWB
Glossy
LCD
1000–1500
cd/m2
Fig. A1.2 Evaluation and correction
of glare in display screen
equipment (DSE) for
medium sized light
sources (10° angular
diameter) such as small
windows or skylights
Matt
LCD
Project
IWB
Abbreviations and symbols
LB = background luminance on display screen (cd/m2); LCD = liquid crystal display; IWB = interactive white board;
‘Positive’ polarity means dark text on light background; ‘Negative’ polarity means light text on dark background
102
Lighting Guide 5: Lighting for education
Size of
light source
Brightness of
light source
DSE
type
DSE
polarity
Suggestion
< 500 cd/m2
All
types
All
polarities
OK to use
Negative
Change display polarity or surface finish
Positive
OK to use
Negative
OK to use
Positive
OK to use
Negative
OK to use
Positive
OK to use
Negative
Change display polarity or surface finish
Positive
OK to use if LB > 300 cd/m2 or change finish
Negative
OK to use
Positive
OK to use
Negative
OK to use
Positive
OK to use
Negative
Change display polarity or surface finish
Positive
OK to use if LB > 500 cd/m2 or change finish
Negative
OK to use
Positive
OK to use
Negative
Change display polarity
Positive
OK to use
Negative
Change display polarity or surface finish
Positive
OK to use if LB > 800 cd/m2 or change finish
Negative
OK to use
Positive
OK to use
Negative
Change display polarity
Positive
OK to use
Glossy
LCD
500–700
cd/m2
Matt
LCD
Project
IWB
Glossy
LCD
700–1000
cd/m2
Matt
LCD
Project
IWB
Angular
diameter 1°
Glossy
LCD
1000–1500
cd/m2
Matt
LCD
Project
IWB
Glossy
LCD
1500–3000
cd/m2
Fig. A1.3 Evaluation and correction
of glare in display screen
equipment (DSE) for small
light sources (1° angular
diameter) such as
luminaires
Matt
LCD
Project
IWB
Abbreviations and symbols
LB = background luminance on display screen (cd/m2); LCD = liquid crystal display; IWB = interactive white board;
‘Positive’ polarity means dark text on light background; ‘Negative’ polarity means light text on dark background
INDEX
Note: page numbers in italics refer to figures; page numbers in bold refer to tables.
Index Terms
Links
A
absence control
34
88
16–17
24
3
90
57–58
90
ante-rooms
57
58
84
anti-panic (escape area) lighting
76
76
77
architectural form and daylighting
13
23–24
24
access doors see entrances
acoustic considerations
adaptation, visual
adjoining spaces
architectural integration
4–5
architectural models
36–37
area lighting see exterior lighting
area-weighted average reflectance
25
art rooms
39
artificial sky
37
60–62
assembly halls see auditoria
atria
14
15
23
40
audience lighting
41–43
52
audio-visual presentation
49
auditoria
39
77
3
21
29
30
battery powered emergency lighting
75
78–79
biodynamic lighting
34
blackout arrangements
47
see also conference rooms; lecture theatres
automatic controls see controls
average illuminance
awnings
B
blinds
66
28–29
see also external blinds; internal blinds
‘borrowed light’
14
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93
24
Index Terms
Links
brise soleil
23
28
BS 5266-1
78
79
BS 5489-1
71
BS 5499
73
BS 8206-2
23
BS EN 1838
73
BS EN 5266
49
BS EN 12193
20
BS EN 12464
20
BS EN 13201
71
BS EN 15193
6
BS EN 50172
78
BS EN 62034
78
BS EN ISO 9241-307
59
BS ISO 3864
73
British Standards
building fabric, and daylight design
building facades
25
31
70
81
7
8
81
59
13
13–14
15
building obstructions
13
25
building orientation
13
67
3
6
canopies
29
30
canteens
40
building form see architectural form
Building Regulations
C
capital costs
9
85
car parking
69
72
CCTV surveillance
72
ceiling heights
23
checklist for lighting design
80–81
chromaticity
90
CIE 1974 general colour rendering index
91
circadian system
10
circulation areas
exterior
68–69
69
interior
39
57–58
classification of spaces
38
This page has been reformatted by Knovel to provide easier navigation.
25
8
Index Terms
Links
classrooms
51
colour interest
33
daylight design
27
depths and heights
23
design tools
40
5
electric lighting
17
natural lighting benefits
11–12
performance requirements
39
veiling reflections and glare
32
clean room classification
62
clerestory windows
14
climate-based daylight modelling
colour appearance
colour interest
colour recognition
60
17–19
4
20
91
20
33
48
3
colour rendering
91
colour rendering index (CRI)
3
39–40
91
colour temperature
4
34
91
53–54
91
committee rooms
common rooms
39
computer display screens see display screen equipment (DSE)
computer modelling
36–37
computer projection
47
49
66–67
84
51–53
77
82
see also interactive whiteboards/display screens
computer visualisation
36–37
concert halls
65
conference rooms
40
94
Construction (Design and Management) Regulations
2
contrast
ambient/task lighting
40
definition
91
room surfaces
20
25
window walls
14
30
see also luminance distribution
contrast rendering factor
91
control rooms
50–51
84
controls
34–35
88–89
blinds and shades
28
checklist
81
This page has been reformatted by Knovel to provide easier navigation.
Index Terms
Links
controls (Cont.)
conference rooms
52
configuration
89
control gear
87–88
daylight sensing
34
energy efficiency
5
input devices
35
88–89
integrated daylighting and electric lighting
17
internal blinds
15
lecture rooms/theatres
48
multi-purpose rooms
56–57
recommended minimum provision
90
special educational needs
67
correlated colour temperature (CCT)
corridors
costs
4
34
39
57
8–10
85
courtyards, daylighting
28
craft rooms
39
60–62
curtains
27
30
cut-off
91
cut-off angle
31
31
20–21
91–92
cylindrical illuminance
91
91
D
dance studios
64–65
daylight design
4–5
committee/meeting rooms
53–54
daylight modelling
17–19
daylight quantity
24–26
lecture rooms
46–47
lighting controls
12
22–31
24–25
40
67
5
multi-purpose rooms
54
performance requirements
40
special educational needs
67
sports halls and gymnasia
63
daylight factor
11–17
24
92
daylight matching lamps
daylight quality
daylight sensing controls
34
26–28
34
35
This page has been reformatted by Knovel to provide easier navigation.
Index Terms
Links
demonstration areas
39
demonstration equipment
85
design and technology areas
32
design checklist
43–44
49
39
60–62
92
80–81
design objectives and constraints
1–2
diffused lighting
92
dimmers
48
dining halls
40
direct lighting
92
directional lighting
21
22
disability glare
29
93
discharge light sources
flicker
32
fluorescent lights
32
high frequency
32
86
87
discharge light sources
high intensity discharge (HID) lamps
32
87
high pressure sodium lamps
41
86
metal halide sources
42
56
86
discomfort glare
29
36
93
display lighting
53
56
display screen equipment (DSE)
58–59
luminance limits
59
59–60
60
veiling reflections and glare
31
32
60
see also interactive whiteboards/display screens
disposal of used equipment
89
drama studios
64
64–65
E
Education (School Premises) Regulations
2–3
efficacy see luminance efficacy targets
efficiency, energy see energy efficiency
electric lighting
17
electrical supply
81
emergency lighting
75
electromagnetic control gear
87
electronic control gear
87
emergency escape lighting
31–35
78–79
72–79
anti-panic (escape area) lighting
76
costs
85
76
This page has been reformatted by Knovel to provide easier navigation.
77
100–102
Index Terms
Links
emergency escape lighting (Cont.)
definition
92
laboratories and workshops
62
lecture rooms/theatres
49
emergency power supplies
75
end user needs and preferences
13
energy consumption
17
5
energy efficiency
5–8
design criteria classes
81–82
8
requirements
5–6
targets
6
Energy Performance in Buildings Directive (EPBD)
Energy-using Products Directive
entrance halls
6–8
7
40
57
49
58
6
5–6
39
entrances
exterior lighting
68
to lecture rooms/theatres
47
environmental design
4–5
passive integration
10
see also daylight design
EPBD (Energy Performance in Buildings Directive)
6
equipment disposal
89
equipment rooms
84
escape area lighting
76
76
77
escape route lighting
73–76
74
76
escape route signage
72–73
exhibition lighting
56
exit signs
49
72–73
68–72
69
external blinds
28
29
external building obstructions
13
25
25
external shades
28
29
29
exterior lighting
external view
26–28
F
facade design
13–14
fibre optic light distribution
16
fire risk assessment
76
flicker
32
flip charts
53
15
92
This page has been reformatted by Knovel to provide easier navigation.
76
30
Index Terms
Links
floodlighting
69–71
fluorescent lights
32
footways
72
86
87
foyers see entrance halls
full height glazing
14
full spectrum fluorescent lighting
11
furnishings
48
52–53
games areas
69
69–70
general colour rendering index
91
G
general lighting
3
general purpose halls
70
71
92
64–65
glare, definition
92
glare control
daylighting
28–31
electric lighting
31
escape route lighting
73–74
74
lecture rooms/theatres
42
45
multi-purpose rooms
56
special educational needs
67
46
glazed roofs see rooflights
glazing see windows
gloss finishes
32
gymnasia
40
63
handicraft rooms
39
60–62
hazardous situations
62
73
natural lighting benefits
10
11–12
ultraviolet (UV) radiation
10
H
76
77
76
77
health issues
hearing impairment
67
heliodon
37
high frequency discharge lamps
32
high intensity discharge (HID) lamps
32
87
high pressure sodium lamps
41
86
high risk task areas
62
73
horizontally stacked shading
15
This page has been reformatted by Knovel to provide easier navigation.
Index Terms
Links
human visual system
3
I
illuminance
definition
93
recommended
19
19
39–40
uniformity
25
38
93
see also daylight factor; luminance
immediate surrounding area
independent schools
93
3
indirect lighting
19
information technology (IT) rooms
39
initial illuminance
93
inspection, emergency lighting
93
78–79
installation, emergency lighting
77
installed loading
93
integrated daylighting and electric lighting
17
34
35–36
interactive whiteboards/display screens
32
51
65–66
20
33
48
28–29
29
47
internal glazing
14
28
28
internal shades
28
29
29
interpretation booths
53
ISO 2603
53
IT (information technology) rooms
39
interior decoration
colour interest
conference rooms
52–53
lecture rooms/theatres
48
internal blinds
K
keystone effect
94
kitchens
40
L
laboratories
39
lamp lumen maintenance factor
94
lamp survival factor
94
60–62
lamps
choice of lamp and luminaire
34
41–42
This page has been reformatted by Knovel to provide easier navigation.
86
88
Index Terms
Links
lamps (Cont.)
correlated colour temperature (CCT)
4
34
luminaire efficacy
6
8
31
31
31
41
45–51
94
83
shielding angles
91
see also discharge light sources; LEDs (light emitting diodes)
language laboratories
39
lecture attendants
84
lecture rooms
39
lecture theatres
41–51
daylighting
40
definition
94
lighting and projection control
84
lighting maintenance
82
management
85
83–85
performance requirements
LEDs (light emitting diodes)
drivers
39
77
32
41
75
40
62
87–88
legal requirements
2–3
daylight design
17
energy efficiency
6–8
libraries
39
life cycle costs
9
light nuisance
70–71
light output ratio
94
light pipes
16
light pollution
70–71
light traps
49–50
light trespass
71
71
71
lighting controls see controls
lighting energy numeric indicator (LENI)
6
7
lighting scenes
35
48
lightshelves
15
lightwells
14
lines of sight see sight lines
lobbies
57
local lighting
94
localised lighting
67–68
58
94
see also task lighting
log books, emergency lighting
79
louvre blinds
29
This page has been reformatted by Knovel to provide easier navigation.
94
Index Terms
Links
low voltage light sources
87
luminaires
cut-off angle
31
31
91
emergency lighting
74
74
75
78
light output ratio
94
lighting fitting
95
maintenance factor
95
mounting height
56
60
100–102
selection checklist
58
80–81
spacing/height ratio
95
task lighting
68
see also lamps
luminance
definition
94
for display screen equipment
59
59–60
3
90
3–4
29
24–25
28
see also illuminance
luminance adaptation
luminance distribution
daylighting
modelling
33
36
task/ambient lighting
luminaire efficacy targets
5
40
6
6
8
M
machine rooms
32
mains ripple
32
maintained illuminance
39–40
93
maintenance
8
82–83
checklist
81
emergency lighting
77–79
maximum illuminance
93
mean cylindrical illuminance
20–21
meeting rooms
40
53–54
metal halide sources
42
56
microstructure prismatic materials
16
mnimum illuminance
93
modelling
36–37
modeling index
21
22
motion detectors see presence detectors
This page has been reformatted by Knovel to provide easier navigation.
86
Index Terms
Links
mounting height
95
emergency lighting
74
75
luminaires
56
58
safety signs
73
multi-purpose halls
64–65
multi-purpose rooms
54–57
music practice rooms
39
musical performances
65
95
N
natural lighting
design considerations
12–17
learning and health benefits
11–12
see alsodaylight design
natural ventilation
23
no-sky line
26
24
O
offices
40
operational costs
9
85
orientation of building
13
67
outdoor learning
11
outdoor lighting
68–72
69
parking areas
69
72
passive integration
10
pedestrian footways
72
performance requirements
38
39–40
escape area lighting
76
77
exterior lighting
69
71
P
photocell control
89
photoluminescent signs
78
planning submissions
16
power supplies for emergency lighting
75
78–79
practical work, rooms for
39
51
60–62
preparation rooms
39
58
84
presence detectors
88
This page has been reformatted by Knovel to provide easier navigation.
95
Index Terms
Links
presentation areas
lecture rooms/theatres
43–44
teaching rooms
47–48
51
presentation walls
20
privacy problems
27
projection screens
65–67
29
see also computer projection
psychological effects
10–11
R
raked seating
42
reception areas
40
recycling
9
reflectance, definition
95
reflective surfaces
14
Regulatory Reform (Fire) Order (2005)
76
remote testing, emergency lighting
44
44
10
89
16
19
20
78–79
retractable screens
29
30
road lighting
71
71
roof overhangs
30
rooflights
14
daylight factor
24
daylight factor calculation
25
discomfort glare
30
lecture rooms
47
room depth
23
room function and daylight design
13
room index
95
15
30
26
26
room surfaces
colour
20
33
reflectance
14
16
wall lighting
35
S
safety signs
72–73
73
‘scene setting’ controls
35
48
science laboratories
39
60–62
seasonal affective disorder (SAD)
security lighting
10–11
72
This page has been reformatted by Knovel to provide easier navigation.
19
20
Index Terms
Links
self-luminous signs
78
self-testing, emergency lighting
semi-direct lighting
78–79
95
service schedules, emergency lighting
78–79
servicing, emergency lighting
77–78
shading, and architectural form
23
shading systems
15
30
44
45
see also blinds; external shades; internal shades
sight lines, lecture rooms/theatres
signage, escape routes
46
72–73
sky luminance
29
30
23–24
28–31
36
40
67
skylights see rooflights
solar design
space planning
23
spacing/height ratio
95
special educational needs (SEN)
13
splayed reveals
30
sports halls
40
55
63
77
sports pitches
69
69–70
70
71
spotlights
45
50
56
staff rooms/offices
39
stage areas
49–50
56
staircases
39
57–58
74
stock rooms
39
stroboscopic effects
32
62
96
sunlight
human exposure to
11
penetration into building
36
redirection systems
16
shading systems
15
see also solar design
supplier registration
9
surface finishes
32
48
54
surface reflectance
14
16
19
20
9
9
85
95
sustainability issues
swimming pools
5
40
switches see controls
This page has been reformatted by Knovel to provide easier navigation.
Index Terms
Links
T
task lighting
67–68
and ambient lighting
5
design checklist
40
80–81
emergency
62
73
76
64–65
teaching rooms, definition
96
technical drawing rooms
39
television equipment
66
testing, emergency lighting
77
theatrical lighting
50
64
49–51
65
13
15
theatrical presentations
thermal design, and daylight design
timers
77
88–89
transformers, for low voltage light sources
87
U
ultraviolet (UV) radiation
10
unified glare rating (UGR)
31
useful daylight illuminance (UDI)
39–40
18–19
V
veiling reflections
32–33
96
ventilation
23
24
vertical shading
15
video equipment
66
view (outlook)
28
26–28
virtual daylight models
36
vision, human
3
visual acuity
96
visual aids
37
66–67
visual amenity
3–4
visual clutter
83
visual comfort
19
visual field
96
visual function
33
96
3
visual impairment
67
visual interest
3–4
4
3–4
4
see also colour interest
visual lightness
This page has been reformatted by Knovel to provide easier navigation.
19
47
Index Terms
Links
visual performance
96
W
waiting areas
58
wall lighting
35
wall thickness, and daylight design
13
Waste Electrical and Electronic Equipment (WEEE) Regulations
whiteboards
9
89
53
65–66
lighting design
32–33
luminaires
65–66
66
presentation walls
20
29
veiling reflections
32
see also interactive whiteboards/display screens
window walls
windows
daylight design
lecture rooms/theatres
14
30
4
30
13–14
14
47
view
26–28
wall contrast
14
30
39
60–62
see also rooflights; shading systems
workshops
This page has been reformatted by Knovel to provide easier navigation.
23
25–26