Sustainable and energy-efficient lighting systems which put human
needs in the foreground: Guiding Light and iNSPiRe
Laner M., Fusco M., Pohl W., Weitlaner R.
Bartenbach GmbH, Austria
Abstract
Demographic change progresses inexorably and predicts a fast growing lifespan in the next decades
[1]. To allow people a long, independent life in health and well-being, specific lighting needs have to
be addressed. In particular elderly people require a multiple amount of light in contrast to younger
ones [2]. Additionally holistic and efficient approaches for the refurbishment of Europe's old buildings
will play a key role in future lighting solutions.
This paper gives examples of Bartenbach's efforts in order to develop new, technically innovative
approaches for sustainable and energy-efficient lighting systems, which puts the visual and
biological needs of (elderly) people in the foreground, showing the approaches of two recent
1
2
research projects: Guiding Light and Inspire .
1- Introduction to the current lighting situation of Europeans private
apartments
According to countless studies focused in particular on older people, light effects (i.e. light
incorporated via the eye) can be described on the following three levels [3]:
•
visual light effects (allow stress-free information recording also at higher age)
•
emotional lighting effects (mood by making special light environments, perch on preferred
color temperature and brightness level of the elderly, considering also aesthetic lighting
design and easy user interfaces [4])
•
biological light effects (affect sleep, mood, physical activity, cognitive information processing
and other key circadian physiological processes [5], [6]).
Some field studies in recent years were able to show that these three levels remain largely ignored
within private homes (of elderly) [7], [8], [9]. Inefficient lighting in areas with increased need for visual
performance shows significantly less than 500 lux horizontal illuminance. For example 500 lux are
recommended at work places as minimum level. But such magnitudes are not sufficient for a stresspoor vision in old age [2]. Also the illuminance level at the eye (important for biological effects) is in
general below 200 lux, especially in areas further away from the window [10], [11]. Further
measurements of illumination levels executed in private houses in the course of recent Bartenbach
research projects show that the typical average illuminance in the residential sector range from 50 lux
to 100 lux. Indeed, in the most of the examined apartments were assessed a lack of illumination to
satisfy any specific task requirements.
Summarizing, currently private homes (especially of elderly people)
•
are mainly lit by daylight during the day with unevenly distributed light levels indoors (e.g. high
light levels near the windows and low light levels in the back)
1
Guiding Light is a 3 year AAL- funded project (with national co-funding) including 6 partners in research on light assistance for
spatial orientation of old people. URL: http://guiding-light.labs.fhv.at/
2
iNSPiRe is a four-year, EC-funded project that see the collaboration of 24 partners across nine work packages from the
combined fields of research and development, industry, small business and not-for-profit organizations. URL:
http://www.inspirefp7.eu/
•
are illuminated with artificial lighting systems in areas and rooms with a lack of daylight or for
task lighting which often are not used during day- and nighttimes or provide an illumination
which doesn’t fulfill basic physiological lighting requirement of elderly people (e.g. glare-free
higher illuminance levels).
Nevertheless, people all over Europe do not recognize their illumination at home as a significant
problem. Noise from outside, pollution or high indoor temperature in summer have been named as
more imported problems at home (see Figure 1).
Figure 1 Subjective problems with housing [5]
With sophisticated LED based luminaires a lighting design can be applied to enhance significantly the
lighting situation in private homes. Light effects of all three levels can be generated using
approximately the same amount of electrical power consumption by utilizing (intelligent and LED
based) dynamic lighting. Already in the last years energy saves due to the use of LED technology in
residential buildings have been noticed. This was mainly driven by the ban of conventional
incandescent bulbs [12]. Energy consumption can be further reduced of 40% and more by automatic
lighting control (sensors) [13].
Starting from those general statements, the aim of this paper is to show a new approach in relation to
psychological and physiological effects of lighting -through two current research projects- and to
highlight the necessity to put human needs at the first place in the development of sustainable lighting
solution.
Knowledge on human lighting needs founded on a scientific base has been the main driver to provide
a significant added value to current standard approaches based on energy saving, improving the
ambient quality in people everyday life.
2- New lighting for fulfilling human lighting needs in (smart) domestic
appliances
With the following lighting approach we aim to establish significant improvements in domestic lighting
appliances focusing on human needs, additionally to energy efficiency. In a subsequent chapter two
different project implementations of this approach are shown.
Lighting design concept
The lighting concept consists of separate ambient- and task lighting (controlled separately, multitude
of lighting scenarios, adapted to use cases).
2
Based on the daily structure (e.g. using the activities of daily life (ADL) and assigning it to the times of
a usual day) of the inhabitant, a pre-adjustment of illuminance level of lighting for different day times
and room zones have been set up [14]. Special attention is focused onto the increased glare
sensitivity (typical of elderly). Therefore studies on brilliance have been carried out to determine the
transition between perception of sparkles and negative glare. This technical feature has been
considered already during the development and the implementation of the optical components into the
luminaires. In order to realize a biological effect the lighting design pays attention to a well-balanced
ambient brightening (realized by increased vertical illuminance levels).
2.1 Ambient room lighting
We define as ambient lighting the basic lighting of the whole room / apartment, i.e. the ambient light
provides the overall minimum illumination, in order to guarantee the basic visual functions, and to
move and orientate between the different spatial zones. Basically, ambient room lighting components
are switched automatically in case of the presence of a person and are subject to the amount of
daylight entering the room.
A control strategy is predisposed so that at the presence detection the room is illuminated very
homogeneous with 300 lux and 4000 Kelvin at floor level between getting up and 2,5 hours before
going (usually) to bed. Within the next half hour the colour temperature of the ambient light is reduced
from 4000 Kelvin to 2200 Kelvin and the illuminance level is dimmed imperceptibly from 300 lux to
150 lux (The ultra warm-white light colour is achievable with LEDs available on the market: e.g. Cree
XT-E). This is preluding the sleeping phase. Within the two hours of going to bed illuminance levels
are further reduced to 50 lux (the time range of dimming is 30 min). When the bed is left during the
night times rooms are illuminated with a maximum of 50 lux and a colour temperature of 2200 Kelvin.
Individual adaptation to lower brightness during night times hours is possible on request of the
inhabitant.
Table 1 - Overview of ambient room lighting parameters
Time
CCT [K]
(horizontal) illuminance [lux]
Day (dawn optional)
4000
300
Evening
2200
150
Night
2200
< 50
A special optional feature of the ambient lighting components in the bedroom is to simulate an
artificial dawn for ease of waking up and getting up. This light alarm clock function increases
exponentially the room brightness from 0 to 300 lux, starting half an hour before intended awakening
and changing colour temperature from 5700 Kelvin to 4000 Kelvin.
To sum up, ambient lighting should support
•
the visual needs for spatial orientation, safe navigation and strainless visual information
processing and
•
the non-visual needs for temporal orientation, stable sleep-/wake rhythm, vigilance and bright
mood
by means of an individualized lighting control scheme.
2.2 Task lighting
As task lighting we define a zonally illumination for defined spatial zones (which are characterized with
major visual needs).
Basically task lighting should always be adapted to the individual visual needs of the inhabitant with
illuminance levels up to 2000 lux. This task light control strategy is based on an exclusive manual
operation. For a comfortable and frequent use of the task lights, the corresponding light switches are
mounted within reach of the tasks. From getting out of bed to 2,5 hours before going to bed again task
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lighting is switched on manually and a predefined optimal brightness level with 4000 Kelvin illuminate
the task areas. Over a time span of 30 min task lighting is changed indiscernibly in colour temperature
from 4000 Kelvin to 2200 Kelvin and the optimal daytime brightness is dimmed to a third. This setting
of the zonally lighting remains during the evening and night. Again brightness levels of the task
lighting components can be further reduced at the request of the inhabitant during night times.
Table 2 - Overview of task lighting parameters
Time
CCT [K]
(horizontal) illuminance [lux]
Day
4000
1000 (up to 2000)
Evening
2200
300 (up to 1000)
Night
2200
< 300
3- Implementation of energy-efficient lighting focusing on human needs:
results from research projects
3.1 Guiding Light
Guiding Light focuses on the development of an intelligent light assistance system for domestic use,
especially for elderly people. Light is used to meet visual needs (e.g. decrease risks of falling), is
applied for temporal orientation (e.g. stabilizing circadian rhythm) and for spatial navigation (e.g.
illumination of defined areas). Light, therefore has great potential for attenuation of age-related
mobility impairments caused by reduced spatial-temporal orientation.
The lighting design approach, comprising indirect and direct lighting and including a dynamic control
scheme (time-controlled change of brightness and light colour) was implemented into 11 test
apartments in Austria, Germany, Switzerland and Italy. A comparison group of 8 households was
evaluated. This means in total 19 test apartments were evaluated by a field study. The basic houses
were spread over four different countries and this generated experience with different languages
(German and Italian) as well as experiences with different legal and cultural initial situation in order to
be prepared for a scale-up.
another task light
ambient
lighting
task lights, for
kitchen area
one of the
PIR sensors
gateway,
controller,
WLAN
Figure 2 View into a field test apartment before and after the installation of "Guiding Light"
These two pictures of Figure 2 shows the comparison of one apartment before and after the
installation of a whole Guiding Light system. A whole Guiding Light system consists out of the
following components: lighting design, luminaires of five different types, radio switches, wireless
sensors (motion including illuminance and door contact), gateway and Internet connection, control
algorithm configured onto a cloud computing system.
The automated ambient light switching is implemented with passive infra-red (PIR) sensors, which are
detecting changes in motion of objects radiating heat. Consequently, a special algorithm determines
the probability of room occupancy on the basis of recently transmitted PIR sensor data, i.e. presence
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detection isn’t only depending on motion detected by PIR sensors. “Static” situations (e.g. the
inhabitant is reading and doing only very small hand or arm movements) can be treated by the system
with occupancy algorithms. In order to improve comfort and well-being (of elderly people) a special
strategy for bedroom ambient and task lighting has been defined. The approach is based on
investigation results carried out at Bartenbach. A light switch close to the bed basically allows the
manual switching of the bedroom lighting during the night hours. As a consequence, the ambient
lighting component in the bedroom should be turned off manually by the older person. Information on
the typical times in bed over the last four weeks are used to establish an individual lighting control
algorithm for the ambient lighting components which both varies the light intensity and colour
temperature of the lighting depending on individual sleep-/wake rhythm. The task lighting components
in defined spatial zones with major visual needs must be switched manually.
Mobility parameters of the inhabitants were monitored and the results of analyzing these data was be
used in two different approaches: a) to change the programming of light variations, b) to verify the
hypotheses of the described human light impact. The system impact on the inhabitants was evaluated
by a field study which run over a period of more than 12 months (study end date: April 2015).
Figure 3 Screenshot of web based monitoring tool in expert view (i.e. not shown to the inhabitants), it
shows the amount of motion detections and real room occupancy (violet marks) and foreseen daily
structure (grey marks)
An online visualisation was developed (see Figure 3). It shows the amount of motion which was
detected for different room zones. Out of this a set of parameters (room zone stay, outdoor stays,
amount of mobility, sleep time, etc.) is calculated and shown in the "expert view". This gives at any
time insight to these kind of "health information" and can be shared with persons of trust (e.g.
relatives, doctor, etc.). It is not shown directly to the inhabitants, therefore a simplified view was used.
This means the “degree of mobility” is an indicator of health [16], [17].
3.2 iNSPiRe
As depicted in the introduction, residential inhabitants live in poorly illuminated environments. The
project iNSPiRe defines a new approach showing that in domestic lighting appliances at least, zoning
(i.e. increasing illuminances according to specific tasks) is absolutely necessary for an improved
(visual) comfort, while not contradicting the idea of reducing energy. Additionally, the term of ‘brillance’
and its effects on objects perception have been investigated to enhance the impact of the developed
technologies.
Illuminance levels have been related to the standard room dimensions of private apartments with the
aim to fulfil the described lighting design. According to those main requirements, the development of
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new lighting solutions have been carried out evaluating sparkle effects and the possibility of glare due
to brilliance. For this reason, the parameters of brilliant appearance relative to residential lighting have
been defined as listed in table 3, where have been identified values of luminance alteration
, visual
angle
and luminance gradients
influencing sparkle phenomena. Those parameters, together
with geometrical and ambient factors have been design drivers in the development of new
sophisticated lighting technologies.
Table 3 Main variables influencing overall appearance and phenomena of sparkle.
Parameter
Values
for sharp luminance profile;
10
~10 cd/(m² rad)
for small "glossy points" ; <1’
7
for large luminance alteration, > 10 cd/m² (except
very small glossy points)
The combined requirements mentioned above result in the development of customized luminaires
ready to be integrated into multifunctional prefabricated ceiling panels. In addition a multi-criteria
analysis has been defined in order to set up an overall refurbishment strategy.
The research process results in the development of two main luminaires:
•
a suspended luminaire with advanced optic components for living/dining rooms
•
a LED spotlight solution called “recessed luminaire”
In order to improve comfort as well as to optimize the light impact, the luminaires allows to vary
intensity, correlated colour temperature (Melatonin-adapted in night times), and the light intensity
distribution (varying direct-indirect component, being adaptable to the subjective users demand).
Pendant (suspended luminaire)
Lighting a whole room out of one single point located on the ceiling is not possible without the
insurgence of glare problems. Starting from the objective to illuminate living rooms out of one single
position ensuring comfort, a pendant luminaire based on an advanced lens system has been
developed within iNSPiRe. The research design process has been carried out with the ambition to
provide specific task-zone lighting combined with a well balanced indirect illumination and to avoid
disability glare as well as sparkle discomfort effects. Thanks to a hybrid optics light engine combined
with a complex surface lens system, the resulting luminaire produces a structured luminance
distribution at the ceiling (atmosphere lighting) as well as a perfect non-glaring zoning on the specific
task area. Almost 25% of the light which hits the plate (~ max. 1150lm) can be controlled by the
spherical reflective surfaces, creating a well-balanced luminance between the indirect light
homogeneously distributed by the plate and the lighting patterns.
No disturbing sparkle effects are perceived by the observer in every point of the selected room area.
Furthermore, multi-shadow effects are reduced and the optical design results in comfortable and
controlled LIDs (luminous intensity distribution).
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Figure 4 Rendered visualization of the pendant luminaire with wo possible patterns
investigated.)
Figure 5 Mock-up of the pendant luminaire (indirect and direct lighting distribution); 3D printed
lens (indirect light distribution)
Recessed luminaires
Spheres luminaires are conceived to be installed as general lighting as well as to be applied in
specific spatial zones (corridors, shelves, etc.). According with the general Bartenbach approach
described in chapter 2, main peculiarity of the optical development has been to ensure highly glarefree properties. A facetted reflector technology has been optimized by the use of advanced complex
surface design. Thermal tests show that due to lower temperatures because of the integration into the
active panel, the efficacy and lifetime of those LED spots increase by approximately 3%.
The recessed luminaire can be smoothly integrated into every kind of ceiling panel and 3D rotated of
25 degrees to allow the user the full flexibility in positioning the light source according to his/her needs
without varying the anti-glare properties. Correlated color temperature can vary from 2200 to 5000K
and allows to set different dynamic lighting scenaria.
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Figure 6 Photo of a sample of the recessed luminaire: sphere of aluminium holding the
reflector
The recessed luminaires are particularly suitable to retrofit intervention and can be installed from the
bottom side of a suspended ceiling panel. Having a diameter of max. 50 mm and a maximum height
of 30 mm, spheres can be integrated in standard active ceiling available on the market.
Summary
Within the segment of private apartments the application of LED lamps is strongly increasing, i.e. this
is reducing in general the energy consumption. But simple retrofitting is not enough to generate any
added values. Numerous studies are showing the poor illumination situation in private homes and the
missing awareness of this situation for the majority of those affected.
With the presented research projects we demonstrate the implementation of new lighting which
improves significantly the comfort and wellbeing of the inhabitants without increasing the energy
consumption.
In particular in Guiding Light it turns out that for conversion from conventional house lighting to LED
based lighting by considering constant energy consumption more than six times as much "light flux"
can be implemented (LED and luminaire efficiency of 2014), i.e. the threshold for "partial biologically
active illumination" is achieved, at constant energy costs. Furthermore within Guiding Light a dynamic
lighting system for residential use was successfully implemented in private homes.
Within the project iNSPiRE the aim is to reduce the lighting energy consumption by at least 50% and
the primary energy consumption in a building to 50kWh/m²/year although the human lighting needs
are put in the foreground. In iNSPiRE this goal is achieved by considering zonal lighting design and
by the development of sophisticated luminaires (pendant and recessed luminaire integrated into
ceiling panels dedicated to refurbishment). Inspire shows that industrialization and development of
standard components can be well combined with the production of high quality luminaires, able to
ensure high comfort levels and high energy performances at a market price.
Through intelligent control algorithms and daylight sensors further potential energy savings can still be
lifted. However, this is associated with too much increased investment costs, and from today's
perspective for private homes not yet ready for the market.
Acknowledgment
The project Guiding Light is funded under the European Ambient Assisted Living Joint Programme
(Grand No. AAL-2011-4-033), project coordinator is Prof. Guido Kempter (University of Applied
Sciences Vorarlberg, Austria). Further members of the Guiding Light consortium are: Tridonic GmbH
& Co KG (Austria), Bartenbach GmbH (Austria), myVitali AG (Switzerland), Institute of Social
Research and Opinion Polling O.H.G. (Italy), Youse GmbH (Germany).
The project Inspire is funded under the European Commission’s 7th Framework Programme 20072013 (Grand No. 314461); project coordinator is EURAC (European Academy of Bozen/Bolzano).
The authors wish to express their gratitude for this financial support.
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