REPORT
19-27 YOUNG STREET
KENSINGTON
LONDON W8
DAYLIGHT, SUNLIGHT & OVERSHADOWING
AUGUST 2013
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CONTENTS OF REPORT
Page
1.
SUMMARY
1
2.
PLANNING POLICY & METHOD OF CALCULATION
3
3.
DAYLIGHT
Neighbouring Properties
Proposed Accommodation
11
14
4
SUNLIGHT
Neighbouring Properties
Proposed Accommodation
16
16
5.
OVERSHADOWING
21 March and 21 June
20
Appendices:
1.
Location Plan and Modelling
2.
Daylight and Sunlight Results:
Neighbouring Properties
3.
Daylight Results:
Proposed Accommodation
4.
Overshadowing:
Overshadowing Images
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Daylight, Sunlight & Overshadowing
We are instructed by Grainger Kensington & Chelsea Limited to advise and report upon the
daylight, sunlight and overshadowing aspects of this planning application.
This report is based upon the scheme drawings prepared by Assael Architecture, a site
inspection and photographs, a topographic survey, 3D modelling, plus daylight, sunlight and
shadow studies.
1.0
SUMMARY
1.1
This report has been drafted by reference to the Building Research Establishment (BRE)
Publication 2011, ‘Site Layout Planning for Daylight and Sunlight: A guide to good
practice’, the London Plan House SPG 2012 and the requirements of the Royal Borough
of Kensington & Chelsea (RBKC) Local Development Framework (LDF), with particular
reference to the Core Strategy.
1.2
A large number of windows serving neighbouring residential properties have a view of
this development site. Daylight to these residential buildings would continue to satisfy
BRE criteria and the relevant policy of the Core Strategy. In most locations there would
be no change or, an improvement in daylight received. An unusual and particularly
positive outcome for any development in a central location.
1.3
Similarly, sunlight to neighbouring residential buildings would, in almost all locations,
remain unchanged and easily satisfy BRE criteria and RBKC policy.
Within the
development the arrangements of rooms would be more successful in benefitting from
sunlight than the example of good practice provided by BRE.
1.4
Overshadowing has no effect on neighbouring amenity zones.
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1.5
Within the central courtyard sunlight would be received in March but some shading is
inevitable. This would be much reduced in time and is a good outcome in this location.
1.6
BVP have worked closely with Assael to ensure the optimum number of rooms benefit
from the BRE recommended value for daylight. This is never easy to achieve in a central
location but this has been achieved in 136 of 143 rooms, 95.1%. A remarkably good
outcome within the constraints imposed by the site.
1.7
Sunlight availability within proposed accommodation inevitably reflects aspect. A great
deal of attention to layouts has ensured that as many living rooms as possible would
benefit from the recommended aspects of south, west and east. The arrangement of
these rooms would be more successful in capturing sunlight than the example of good
practice provided by BRE.
1.8
Overshadowing of neighbouring amenity zones would not vary from existing conditions.
Because these zones are relatively small, this is to be welcomed.
1.9
Within the proposed central courtyard overshadowing would satisfy BRE recommended
levels, which is difficult to achieve in a central location.
1.10
Taken overall, the results within this report are extremely good for a development in this
central location, with immediately adjacent buildings on three sides and a relatively
narrow street (Young Street) on the fourth side, and more buildings to consider. The
outcome satisfies BRE’s recommendations, the London Plan Housing SPG and the
Royal Borough of Kensington & Chelsea’s Core Strategy.
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2.0
PLANNING POLICY & METHOD OF CALCULATION
Local Planning Policy
2.1
RBKC’s Core Strategy, adopted December 2010, sets out the vision, objectives and
detailed spatial strategy for future development in the Royal Borough. Under the heading
of “Amenity” the Council makes reference to daylight and sunlight.
34.3.46 (extract)
“The Council considers that proposals for new residential and non-residential
development should ensure a reasonable standard of visual privacy and provide good
conditions for daylight and sunlight, taking into account the amenity conditions of the
surrounding area. In assessing the effect of new development on light conditions, the
Council will have regard to the guidelines in ‘Site Layout for Daylight and Sunlight: A
Guide to Good Practice’ published by the Building Research Establishment.”
The Core Strategy then makes the following policy statement:-
Policy CL5
Amenity
“The Council will require new buildings, extensions and modifications and small-scale
alterations and additions, to achieve high standards of amenity. To deliver this, the
Council will:
a) Require good daylight and sunlight amenity for buildings and spaces, and that the
conditions of existing adjoining buildings and amenity spaces are not significantly
reduced or, where they are already substandard, that there should be no material
worsening of the conditions;”
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There are other items referred to under this Policy but these are not relevant to the terms
of this Report, except:“o) Require the affordable and market housing to have equivalent amenity in relation to
factors including views, daylight, noise and proximity to open space, play space,
community facilities and shops.”
London Plan, 2011 - Implementation Framework
2.2
More recently, the Mayor has issued his Supplementary Planning Guidance for Housing,
November 2012. This provides guidance on daylight and sunlight issues by reference to
the following:
Baseline Standards are those endorsed by the Mayor as addressing issues of particular
strategic concern.
Good Practice Standards are those put forward by the Mayor as representing general
good practice.
Daylight and Sunlight
Baseline
Standard 5.2.1“Developments should avoid single aspect dwellings that are north facing, exposed to
noise levels above which significant adverse effects on health and quality of life occur, or
contain three or more bedrooms.
Note:
“North facing is usually defined as an orientation 45 degrees either side of due
north.”
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Good Practice
Standard 5.5.1“Glazing to all habitable rooms should be not less than 20% of the internal floor area of
the room”.
However, it is worth noting that this Standard is apparently provided in order to define an
easy means of providing daylight within a room but, as the Average Daylight Factor
calculation confirms (see items 2.9 to 2.11 of this Report), glazed area is only one
element of ensuring that a room benefits from good daylight. We have therefore based
our Report on ADF rather than this Good Practice rule of thumb.
Standard 5.5.2“All homes should provide for direct sunlight to enter at least one habitable room for part
of the day. Living areas and kitchen dining spaces should preferably receive direct
sunlight.”
Building Research Establishment 2011, Site Layout Planning For Daylight &
Sunlight. A Guide To Good Practice
2.3
Both the Royal Borough of Kensington & Chelsea’s Core Strategy and the Mayor of
London’s Guidance require a means of analysis. This is conventionally carried out by
reference to this BRE publication which, as has already been noted, is specifically
referred to by RBKC under the heading of “Amenity.” The guide does not contain
mandatory requirements but in the Introduction provides a full explanation of its purpose:
“The Guide is intended for building designers and their clients, consultants and planning
officials.”
“The advice given here is not mandatory and this document should not be seen as an
instrument of planning policy.”
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-6“It aims to help rather than constrain the designer.”
“Although it gives numerical guidelines these should be interpreted flexibly since natural
lighting is only one of many factors in site layout design.”
“In special circumstances the developer or planning authority may wish to use different
target levels. For example, in an historic city centre, or in an area with high rise buildings,
a higher degree of obstruction may be un avoidable if new developments are to match
the height and proportions of existing buildings.”
Daylight
2.4
Reference is made in the BRE report to various methods of assessing the effect a
development will have on diffused daylight.
2.5
The simplest methods are not appropriate in an urban environment, where the built form
is invariably complex. Vertical Sky Component (VSC) is the calculation most readily
adopted, as the principles of calculation can be established by relating the location of any
particular window to the existing and proposed, built environment.
2.6
The BRE Guide states “If any part of a new building or extension, measured in a vertical
section perpendicular to a main window wall of an existing building, from the centre of
the lowest window, subtends an angle of more than 25o to the horizontal, then the diffused
daylighting of the existing building may be adversely affected.
This will be the case if the Vertical Sky Component measured at the centre of an existing
main window is less than 27o and less than 0.8 times its former value”.
2.7
BRE also recommend that Daylight Distribution (DD) within neighbouring properties
should remain at least 0.8 the former value. However, it is rare that access is available
to neighbouring properties and we have therefore taken a reasoned approach to this, as
further detailed in the body of our report.
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2.8
Our analysis of proposed accommodation is based upon the more comprehensive
calculation of Average Daylight Factor (ADF). This is recommended by BRE in relation
to proposed accommodation as it is a more comprehensive measure of daylight and in
order to quantify it, requires a great deal of information that is readily available. This uses
the VSC calculation in order to confirm the angle of visible sky and then goes on to
consider the area of glazing receiving light and the transmittance qualities of the glass.
This is then related to the internal room surface and the reflectance value within the room.
BRE provides a default value for each of these factors, which we have maintained or
varied as appropriate. For example, permanent, light coloured floor finishes (lacquered
or similar) will be laid, and this allows the internal surface default value of 0.5 and floor
reflectance value of 0.15, which assumes a buff coloured tufted carpet, to be revised.
The values used in our analysis are detailed in paragraph 2.11.
2.9
The BRE guide recommends ADFs for rooms where complementary artificial lighting is
also available, of at least:
2%
Kitchens and living space in open plan with kitchen (where kitchens are
contained within a confining partition, they are considered as internal rooms, lit
by task lighting in accordance with the modern mode)
2.10
1.5%
Living rooms and home studies
1%
Bedrooms
Where a room is served by more than one window, ADF calculations are made in relation
to each window and the individual results added together to provide the true ADF for that
room. It should also be noted that full height glazing requires individual ADF calculations
for those parts above and below the reference plain of 850mm above floor level. Hence
the designation ‘L’ and ‘U’ against some of the results.
2.11
The default and other values used in order to calculate ADF are:
Glazing transmittance - 0.68 for double glazing (BRE default reading)
Net glazed area of the window - 0.8 (BRE default reading)
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Interior surface reflectance:
Living rooms and kitchens - 0.6 (BRE default 0.5)
Bedrooms - 0.5 (BRE default 0.5)
Floor reflectance:
Living rooms and kitchens - 0.5 (BRE default 0.15)
Bedrooms - 0.15 (BRE default 0.15)
Sunlight
2.12
BRE’s Guide to Good Practice confirms the criteria relevant to neighbouring residential
properties and proposed accommodation.
2.13
Sunlight is only relevant to neighbouring residential properties:-
i.
Which have a view of the proposed development and face within 90o of south,
i.e. south of the east west axis;
ii.
If any part of a new development subtends an angle of more than 25o to the
horizontal measured from the centre of the main living room window, a vertical
section perpendicular to the window then the sunlighting in the existing dwelling
may be adversely affected;
iii.
Similarly, the sunlighting of the existing dwelling may be adversely affected if the
centre of the window receives less than 25o of the annual probable sunlight hours,
of which 5% of the annual total should be received between 21 September and
21 March (winter) and less than 0.8 times its former sunlight hours during either
period.
iv.
Kitchens and bedrooms are less important, although care should be taken not to
block too much sun.
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2.14
Proposed accommodation “will appear reasonably sunlit provided”:●
At least one main window wall faces within 90o of south; and
●
The centre of at least one window to a main living room can receive 25% of annual
probable sunlight hours, including at least 5% of annual probable sunlight hours in
the winter months between 21 September and 21 March.
2.15
BRE acknowledges that a simple layout strategy can be an issue for flats:“Sensitive layout design of flats will attempt to ensure that each individual dwelling has
at least one main living room which can receive a reasonable amount of sunlight. In both
flats and houses, a sensible approach is to try to match internal room layout with
window/wall orientation.
Where possible, living rooms should face the southern or
western parts of the sky and kitchens towards the north or east.
The overall sunlighting potential of a large residential development may be initially
assessed by counting how many dwellings have a window to a main living room facing
south, east or west. The aim should be to minimise the number of dwellings whose living
rooms face solely north, north east or north west, unless there is some compensating
factory such as an appealing view to the north”.
Permanent Overshadowing
2.16
BRE explains that sunlight in the spaces between buildings has an important impact and
is important for a number of reasons. It therefore recommends that:
“The availability of sunlight should be checked for all open spaces where it will be
required, this would normally include:●
Gardens, usually the main back garden of a house;
●
Parks and playing fields;
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Children’s playgrounds;
●
Outdoor swimming pools and paddling pools;
●
Sitting out areas, such as those between non-domestic buildings and in public
squares;
●
2.17
Focal points for views, such as a group of monuments or fountains.
BRE recognises that each of these spaces will have different sunlight requirements and
suggests the Equinox (21 March) is chosen as a date for assessment:“It is recommended that at least half of the amenity areas listed above should receive at
least two hours of sunlight on 21 March. If a detailed calculation cannot be carried out
and the area is a simple shape, it is suggested that the centre of the area should receive
at least two hours of sunlight on 21 March”.
“If an existing garden or outdoor space is already heavily obstructed then any further loss
of sunlight should be kept to a minimum. In this poorly sunlit case, if as a result of new
development the area which can receive two hours of direct sunlight on 21 March is
reduced to less than 0.8 times its former size, this further loss of sunlight is significant”.
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3.0
DAYLIGHT
3.1
Generally
3.1.1 Daylight is not specific to a particular direction, as it is received from the dome of the sky.
It is necessary to consider all neighbouring residential property facing the application site
and all habitable rooms within the proposed buildings, as aspect is irrelevant.
3.1.2 We refer to our plan model and perspective images in Appendix 1. This model is based
upon topographic, architectural and photographic information, collated to produce an
accurate representation of the existing and proposed built environment. For ease of
recognition, neighbouring buildings are detailed in green. The existing site building (to
be demolished) is defined in blue and the proposed building in magenta.
3.1.3 The results in Appendix 2 and 3 can be cross referenced to the model referred to above
and the architect’s plans, both in Appendix 1.
3.1.4 The model has been interrogated by our specialist software in order to confirm daylighting
measured by VSC, DD or ADF, as more fully stated in the body of the report.
Neighbouring Residential Buildings
3.2
North
3.2.1 On the north side of the development site are a number of commercial buildings, none of
which need to be considered for the purposes of this report. Although there are some
residential buildings between the development site and Kensington High Street, these do
not contain windows that face towards the proposed development.
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3.3
East
3.3.1 Immediately to the east of the development site are the rear of numerous residential
apartments fronting Kensington Court.
These are known as Kent House and
Kensington House.
3.3.2 The daylight results for a large number of windows in both properties from lower ground
to third floors are included in Appendix 2.
3.3.3 These results show that there would be almost no reduction in daylight received at the
face of the window. In the majority of locations there would be no change whatsoever
and in many locations, daylight would improve.
3.3.4 Notwithstanding the above commentary, there are some windows that receive less than
the BRE benchmark figure of 27% VSC in the existing condition and inevitably, in the
proposed condition as well.
When this occurs, BRE make the appropriate
recommendation, which is repeated in item 2.6 of this report. This states that an adverse
effect would only occur if the proposed VSC value were not only less than 27% but also
less than 0.8 the former (existing) value.
3.3.5 The results clearly demonstrate that with all proposed values at 0.96 and above, there
would be no adverse effect.
3.3.6 We have already commented on the fact that access is rarely available to neighbouring
property and this is particularly true when there are so many. Whilst therefore we have
not provided figures for Daylight Distribution, there could be no opportunity for the
proposed to be less than 0.8 the former value, with daylight received at the face of the
window 0.96 and better than the existing value. In many cases with no change to, or an
improved, daylight value.
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3.4
South
3.4.1 To the south there are some residential properties, including the accommodation above
the ground floor of the public house and based upon a view from the existing site building,
residential apartments to the rear of 2 and 3 Kensington Square.
3.4.2 Our results are again detailed in Appendix 2. Like the results previously reported, there
would be almost no variation whatsoever in daylight received. The proposed results are
between 0.99 and 1.02 the former value. In the small number of locations where existing
and proposed values are less than the benchmark figure of 27%, there would be no
adverse effect, almost no effect whatsoever. Similarly there could be no adverse effect
on Daylight Distribution.
3.5
West
3.5.1 Young Street is sited on the west side of the development site. The great majority of the
western side of Young Street defines the flank of Barkers and a rear entrance for
commercial buildings. Adjoining this is the administrative centre for Richmond University.
These are both commercial buildings that do not need to be considered for the purposes
of this report.
3.5.2 South of these is a substantial residential home that stands at the corner of Young Street
with Kensington Square, 45 Kensington Square. The flank elevation includes a number
of windows with a view of the development site.
3.5.3 It was far from obvious when viewed from the outside how many of these windows would
serve non habitable space such as hallways, cloakrooms and bathrooms and which
served habitable space. The owner kindly provided access and the results for Vertical
Sky Component and Daylight Distribution are detailed on the last two sheets of
Appendix 2. These results confirm the room type, including rooms that have a view to
Kensington Square, where a window for that room is also located in the flank elevation.
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3.5.4 Once again it can be seen that no matter what the style of room, there would be very little
variation in VSC and no adverse effect. This situation is confirmed by the analysis of
Daylight Distribution, detailed on the last page of Appendix 2, where there would be very
little change and no adverse effect.
Proposed Accommodation
3.6
Daylight To Habitable Rooms
3.6.1 BVP have worked at length with Assael Architecture on the internal layouts to this
development in order to ensure that the optimum number of rooms receive daylight in
accordance with BRE recommendations. This is never easy when dealing with the
confines of an existing site especially as, on this occasion, the existing site building has
been used for an entirely different purpose which, being a car park, required no
consideration of room layout. The results in Appendix 3 confirm that 136 of 143 rooms,
a success rate of 95.1%, automatically satisfy BRE’s required values. In any case, BRE
recognise the difficulties that arise in many urban locations when it confirms with regard
to the Guide:
“Although it gives numerical guidelines, these should be interpreted flexibly since natural
lighting is only one of many factors in site layout design”.
3.7
Daylight Summary
3.7.1 Despite the very large number of neighbouring residential windows with a view of this
development site, the proposed building would not be the cause of an adverse effect and
in the majority of locations, there would either be no effect or an improvement to daylight
readings.
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3.7.2 An exceptionally good set of results has also been confirmed for the proposed
accommodation which has been the subject of Design Development in co-operation
between BVP and Assael Architecture, in order to produce the optimum outcome. This
has been successfully achieved when consideration is also given to the difficulties
created by a site in a very central location, presently used as a car park.
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4.
SUNLIGHT
Neighbouring Properties
4.1
The results for sunlight availability in existing and proposed conditions, measured
annually and during winter months only in accordance with BRE requirements, are
detailed in the two right hand columns of the results in Appendix 2. It will be seen that
some results are merely defined as “north facing”, which means that the window does
not face within 90o of south and BRE defines no criteria, as it is impossible to protect the
intermittent sunlight that these windows would receive during only short periods of the
year.
4.2
All the other results are extremely stable, with almost no variation whatsoever and no
adverse effect. In just a few locations sunlight availability would improve.
Proposed Accommodation
4.3
Sunlight availability to proposed accommodation is inevitably defined by aspect and this
in turn is defined by the location of the site within the existing urban grain. Little is
achieved by referencing a wide variety of sunlight results.
4.4
In acknowledgement of this BRE, as restated in item 2.15 of this report, suggests that:
“The overall sunlighting potential of a large residential development may be initially
assessed by counting how many dwellings have a window to a main living room facing
south, east or west. The aim should be to minimise the number of dwellings whose living
rooms face solely north, north east or north west ….”.
4.5
The proposed building deals with these factors exceptionally well, with 46 living rooms
facing south, east or west and five that do not.
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4.6
Sunlight Summary
4.6.1 Sunlight availability to neighbouring properties would remain almost unchanged, whether
measured annually or through the winter months. An exceptionally good set of results in
this central urban location.
4.6.2 Similarly, proposed accommodation, which is always very difficult to satisfy when seeking
to make the best use of an existing site, would have 46 of 51 living rooms facing south,
east or west as recommended by BRE. This equates to 90% of the main accommodation
and favourably compares to the 80% provided as an example of good practice in BRE’s
guidance.
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5.
OVERSHADOWING
Overshadowing 21 March and 21 June
5.1
Importantly, and by reference to the images in Appendix 4, there would be no variation
in the overshadowing of neighbouring amenity zones and therefore, no increase in
permanent overshadowing and no adverse effect.
5.2
Within the courtyard of the proposed development, sunlight is available at the BRE
reference date of 21 March. However, we have also included transient shadow images
representing 21 June, in order to confirm how good sunlight at the ground would be
around this date.
Overshadowing 21 June
5.2
These images, also Appendix 4 help to confirm the variation that occurs between the
spring/autumn and summer months.
Overshadowing Summary
5.3
Overshadowing to neighbouring amenity zones would not vary.
5.4
Within the proposed courtyard, overshadowing is inevitable as it is with all courtyard
schemes, especially in a central location. Despite this, there would be sunlight received
at courtyard level on 21 March and this amenity would be much improved by 21 June,
not returning to 21 March conditions until 21 September. In our experience, this is a good
outcome.
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APPENDIX 1
LOCATION PLAN AND MODELLING
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APPENDIX 2
DAYLIGHT AND SUNLIGHT RESULTS
NEIGHBOURING PROPERTIES
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APPENDIX 3
DAYLIGHT RESULTS
PROPOSED ACCOMMODATION
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APPENDIX 4
OVERSHADOWING
OVERSHADOWING IMAGES
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