Lighting Design at Workplaces: What Should Be the Concerns for an Architect?

Abstract

The main goal of this article is to clarify and demonstrate that non-visual system should be taken into account at workplaces (offices) by architects, engineers and designers. Factors such as biophilia, the non-visual system, differences between natural and artificial light and illuminance, among others, should be important parameters when conceiving an indoor space especially a workplace environment. Health and wellbeing are much more than a layout or an image. Which questions should be questioned when conceiving a workplace and keep balance between the visual and non-visual systems? That is a question that should have an answer based on several factors, not just the ones concerned with the corporate image and preferences of the professionals in charge of the designing of workplace spaces. To achieve such goals, the research is conducted throughout a literature review and the analysis of two case studies: Camilo Castelo Branco Street and 24th July Avenue, both in Lisbon, Portugal. Lighting Design deserves much more attention.

Full text

Lighting Design at Workplaces: What Should
Be the Concerns for an Architect?
Sandra Preto
(&)
Faculty of Architecture, University of Lisbon, Lisbon, Portugal
sandrapreto@hotmail.com
Abstract. The main goal of this article is to clarify and demonstrate that non-
visual system should be taken into account at workplaces (offices) by architects,
engineers and designers. Factors such as biophilia, the non-visual system, dif-
ferences between natural and artificial light and illuminance, among others,
should be important parameters when conceiving an indoor space especially a
workplace environment. Health and wellbeing are much more than a layout or
an image. Which questions should be questioned when conceiving a workplace
and keep balance between the visual and non-visual systems? That is a question
that should have an answer based on several factors, not just the ones concerned
with the corporate image and preferences of the professionals in charge of the
designing of workplace spaces. To achieve such goals, the research is conducted
throughout a literature review and the analysis of two case studies: Camilo
Castelo Branco Street and 24th July Avenue, both in Lisbon, Portugal. Lighting
Design deserves much more attention.
Keywords: Lighting Design Biophilia Non-visual system 
Natural and artificial light Illuminance Workplaces
1 Introduction
When conceiving an indoor environment, such as a workplace, there are many factors
that are repeatedly ignored, such as biophilia, the non-visual system, the differences
between natural and artificial light, illuminance levels needed at workplaces and the
geographic location and many other characteristics. So, the literature review is going to
clarify their importance. In order, to understand how these parameters are important
two case studies are going to be analysed and discussed. The case studies are the
buildings located in Camilo Castelo Branco Street and in 24th July (east and west
buildings), in Lisbon. Information about the sun exposure in the city of Lisbon
throughout the year, gathered in both case studies and their analysis will be presented.
(This article is part of author’s PhD thesis).
©Springer Nature Switzerland AG 2020
F. Rebelo and M. M. Soares (Eds.): AHFE 2019, AISC 955, pp. 571–583, 2020.
https://doi.org/10.1007/978-3-030-20227-9_54

2 Literature Review
2.1 Biophilia
Natural environments, including gardens or landscapes, make human beings feel better
and healthier, so, not surprisingly; the definition of biophilia is about the connection
between nature and humans. Unfortunately, in the XX and XXI (so far) centuries,
humans were, and continue being, apart from nature, and humans’wellbeing, espe-
cially, psychophysiological is at risk. In a city, for example, humans do not feel so
healthy and happy, due to its artificiality. So, elements of nature should not be taken
away from our lives [1,2]. At workplaces, such as offices, we should have a view to a
green (garden) or blue (sea or river) landscape, sadly, this is not always achievable [3].
Natural views decreases our stress level, and some urban scenes can also have a
positive influence, eventhough it happens more slowly [1].
2.2 Non-visual System
Light influence our visual and non-visual (circadian system) systems [4,5]. Humans
have a light/dark cycle that occurs accordingly to the daily variations of light, which
promote melatonin (darkness hormone), serotonin (mood hormone) and cortisol (stress
hormone) production as well as sleeping-waking systems [6]. Human beings need light
in the morning and darkness in the evening to balance circadian cycles. The same is to
say, that humans need blue light spectrum during the day (not at any time and con-
tinuously) to improve concentration and alertness levels, but in the end of the day (late
afternoon) it should be avoided because it may disrupt our circadian rhythm. Another
important factor is the human retina, since is through the eye that light influence our
visual and non-visual system. The retina has cones and rods (visual photoreceptors)
which have different spectral sensitivities, whereas the rods efficiency has a peak of
sensitivity at 505 nm, while the cone’s peak sensitivity happens at 555 nm, However,
there are also the non-visual (the so-called third photoreceptor, ipRGCs - intrinsically
photopigment retinal ganglion cells) (Fig. 1).
Fig. 1. Spectral absorption of cones and rods (R).
And cones at Long - (L), Medium - (M) and Short -
(S) wavelengths. (adapted from Dartnall, Bowmaker
& Mollon, 1983) [7]
Fig. 2. Biological effect of light on
the human eye: The activating effect
of light depends on the correct angle
of incidence of the light at the eye [8].
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The non-visual (biological) effects of light are mediated by ipRGCs that contains
the photopigment melanopsin, which is more sensitive to short-wavelength light at
480 nm (blue wavelengths). The sensibility of ipRGCs varies in the intensity,
duration/pattern, and timing of light exposure. Moreover, the blue-light exposure is
more effective at enhancing alertness and performance [9]. Nevertheless, the biological
effect of light at the eye also depends on the correct angle of incidence [10] (Fig. 2).
2.3 Natural Versus Artificial Light
Natural and artificial light are very distinct, and the major difference is the dynamics in
its intensity level (illuminance) and light spectrum. Daylight has a positive influence on
human mood, however in indoor spaces the artificial lighting systems cannot have the
same variation throughout the day. This dynamism depends on geographical location,
particularly, latitude and altitude, as well as seasons. Light exposure, for instance,
might be more effective in improving our alertness in the morning after awakening
while in the evening exposure to light should be avoided. Moreover, questions of
gender, chronotypes and age can also be affected by light differently, and that is why it
is so difficult to conceive an environment, since we are all different [11,12].
2.4 Illuminance
The difference between natural and artificial light is very significant, especially in its
illuminance level, since natural light can reach 100.000 lx, with direct sunlight and
10.000 lx in an overcast day [13,14]. However, when we think about non-visual
stimulation we must know that different illuminances have dissimilar impacts and that
2.000 lx is the illuminance recommended for activating the circadian system [7,15,
16]. During working days, since we reduce significantly our mental resources, which
also decreases our alertness, increases psychological stress, and thus there is decrease in
productivity. Higher illuminance levels, for instance can counteract our tiredness and
help us to recover from it [15,17]. Furthermore, the pupil dimension, the thickness of
the lens, the increasing sensitivity to glare due to ageing, so we need higher illuminance
levels [18,19]. Illuminance levels are higher when windows are close to the working
area and decreases as the distance increases (Fig. 3)[20]. Weather conditions, geo-
graphic location, season, time of day, and spatial location, and particularly the position
and dimension of the windows, interior spaces can influence and result in a lack of light
Fig. 3. As the distance from window increases, the illuminance (natural light) decreases [21].
Lighting Design at Workplaces: What Should Be the Concerns for an Architect? 573

due to a lower illuminance level; this fact can be minimised by the support of artificial
light [22]. Seasonal Affective Disorder (SAD) symptoms, for instance, are relieved with
high levels of illuminance (artificial light when the daylight is insufficient).
2.5 Workplace
Humans non-visual system needs are often neglected at workplaces environments, and
lighting design is, most of the times, based on aesthetic parameters and on corporate
image. Only 20% of the offices have illuminances over 1.000 lx at the eye, which is
considered biological darkness. The solution is a lighting system that combines general
and local lighting in order to increase users/workers’wellbeing [19,22]. To achieve a
healthy lighting design layout, light direction should be considered vertical and hori-
zontal light, and it is essential to reduce horizontal illuminance levels [14].
2.6 Lisbon
It is essential to analyse natural, and artificial, light regarding its geographical location,
sun´s position, the number of daily hours with sunlight, weather and built environment
surrounding. Lisbon, according to the sun’s path in the summer (21st June), the sun rises
from the ENE, east-northeast, (azimuth 60°) at 06.12 a.m. and the sunset happens at 09.05
p.m., when the sun is in the WNW, west-northwest (azimuth 300°). During the winter (21st
December), the sun rises from the ESE, east-southeast, at 07:51 a.m. (azimuth 120°) and
the sunset occurs from the WSW, west-southwest, at 5.18 p.m. (azimuth 240°). So, in the
summer there are about 15 h and in the winter there are 9 h of sun exposure (Fig. 4)[23].
3 Case Studies
3.1 Camilo Castelo Branco Street, 4th Floor, Lisbon
The first case study is the office building (Fig. 5) situated between the Camilo Castelo
Branco Street and Actor Tasso Street in Lisbon, and part of the main façade is at Actor
Tasso Street and has no obstacles and has a view to Eduardo VII Park (Fig. 6). From
now on Camilo Castelo Branco building is referred as CCB.
Fig. 4. Solar path diagram (Lisbon) [23].
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Regarding solar path diagram, as we can see (Fig. 7) the main façade is oriented to
WSW and the façade facing Eduardo VII Park for WNW. In the winter, sun moves
from ESE to WSW, the CCB façade is more fortunate with sunlight, whereas in the
summer, when moving from ENE to WNW, the façade at Actor Tasso Street is the
most privileged.
Fig. 6. Aerial view of the CCB to
Eduardo VII Park [24].
Fig. 5. View of the CCB (Actor Tasso
Street) [24].
Fig. 7. Solar exposition of CCB. [adapted
from 24]
Fig. 8. CCB façades. [adapted from 24]
Fig. 9. CCB, openspace on the 4th floor. (layout was ceded and adapted) [Author]
Lighting Design at Workplaces: What Should Be the Concerns for an Architect? 575

In the summer, the sun’s rays of 74°, makes the light more oblique on the façades
during the afternoon. While, in the winter, ray’s of 38° are a little complicated to take
advantage of, because there are other buildings nearby (Fig. 8).
The spatial layout is based on open space, meeting rooms and individual offices. As
for the distance from the workstations to the windows, as can be seen in the spatial
layout (Fig. 9) the workstations in red are over 6.80 m (from Tasso Street Actor), in
orange distance is over 11.10 m (CCB), in blue distance is 9.60 m, in green is 4.50 m
and finally, in rose the distance is over than 5.50 m from Actor Tasso Street.
As for illuminances, the measurements were carried out with a lux meter with a
detachable sensor approved by PQI (Portuguese Quality Institute). Measurements were
made on 22nd January 2018, at 10:00 a.m. and at 4:30 p.m. The illuminances were
measured in the workstations closest to and far from the windows. In blue (rectangles)
are the measurements under the luminaires/lamps and in red (rectangles) without
luminaires/lamps above. In the morning, the highest illuminances did not happen on the
east side as expected, and during the afternoon, the illuminances decreased, even with
luminaires/lamps above. It was not possible to carried out the measurements in the
summer (Fig. 10).
The artificial lighting in the building is recessed, direct, and the luminaires have
aluminum reflectors with two fluorescent lamps, type TL5 HE 25 W/840, which means
that it has a color temperature of 4.000 K (cold), with an IRC of 85 (the maximum is
100) and has an electronic ballast (less flicker). The luminaires are located in suspended
ceiling based on rectangles with 0.30 m by 1 m, placed parallel to the Actor Tasso
Street. Between each line of luminaires there are 6/7 acoustic metal ceiling tiles. One of
the lines of luminaires is located (in the room parallel to the Actor Tasso Street) very
close to the window, only 3 metal tiles away from the windows. There are not task
lights. The angle of the luminaires, relative to the eye, lies in the 0°–30° and 30°–45°.
As for the vertical blinds, these are in PVC (Polyvinyl chloride) in white stripes.
Fig. 10. Illuminances at workstations, CCB building, on the 4th floor. Illuminances at 10.30 a.
m. (dark blue text) and at 4 p.m. (red text). (layout was ceded and adapted) [Author]
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The materials, colours and finishes of the surfaces are relevant, since the comfort of
the non-visual system depends on the visual system, the same is to say that the finish
should be matt in order to do not produce glare and provoke eyestrain. The desks and
furniture are white, there are frontal screens in wood on the desks, the chairs are black,
the floor is grey, the walls and ceilings are white.
3.2 24
th
July Avenue, 3
rd
Floor, East and West Buildings, Lisbon
The two buildings are united by a central body are situated between 24th July Avenue
and D. Luis I Street, the one on the right is going to be referred as west building and the
one on the left east building (Fig. 11). On the waterfront (Fig. 12), is the Tagus River
and its natural landscape where blue predominates, there are no buildings obstructing
the view or the natural light. In the rear façade, the built environment is not very height
(Fig. 12).
Regarding the solar path diagram, as it can been seen in the Fig. 11, the main
façade is facing south. However, the façades where the workstations are located are
oriented to east and west. Both, in summer and in the winter, the building has more
sunlight during the morning on the east façades and during the afternoon on the west
façades. In the winter, the sun moves from ESE to WSW. While in the summer, moves
from ENE to WNW which has more northern light, which is the most constant
throughout the year (Fig. 13). Moreover, the waterfront façade (south) can take more
advantage of sunlight, not only because it is facing south but also since it has no
obstructions, just the Tagus River.
Fig. 11. Main façade (east building on the
right) [24].
Fig. 12. Rear façade and waterfront [24].
Lighting Design at Workplaces: What Should Be the Concerns for an Architect? 577

In the summer, the sun’s rays of 74°, makes the light parallel (from ENE to WNW
(Fig. 13)toD.Luís I Street (rear façade). While, in the winter, ray’sof38ºhas the
same effect but in the main façade (south, from ESE to WSW) (Figs. 13 and 14).
The spatial layout is based on open space, meeting rooms (Fig. 15), indoor and
outdoor lounges, where workers can work and/or rest. As for the distance from the
workstations to the windows, marked in red (Fig. 15), is greater than 4.66 m.
Fig. 13. Solar exposition of 24th July
Avenue building. [adapted from 24]
Fig. 14. Aerial view of 24th July Avenue building
from east façade. [adapted from 24]
Fig. 15. Spatial layout openspace on the 3rd floor, east, at 24th July Avenue. (layout was ceded
and adapted) [Author]
Fig. 16. Iluminances nearby the workstations, on the 3rd floor, east building (on the left is 24th
July Avenue). Illuminances at 11.30 a.m. (dark blue text) and at 6 p.m. (red text). (layout was
ceded and adapted) [Author]
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The illuminances’s measurement were carried out with a lux meter with a
detachable sensor approved by PQI (PQI) on 25th January 2018 at 10:30 p.m. and at
5:00 p.m. at 24th July Avenue. The illuminances were measured in the workstations
next to the windows (Figs. 16 and 17). In the morning, the highest illuminances were
measured on the east side as expected, and in the afternoon decreased greatly.
Unfortunately, it was not possible to carried out the measurements in the summer.
The artificial lighting in the building is recessed, semi-direct (due to frosted glass),
and the lamps are fluorescent and compact fluorescent lamps, and has an electronic
ballast (less flicker). The luminaires are arranged in five longitudinal strips, parallel to
the length of the buildings (Fig. 18). Note that one of the luminaries is central and that
the others appear to be equidistant, however, the last two (east and west sides) are very
close to the windows (Fig. 19). There are not task lights. The angle of incidence of the
luminaires, relative to the eye, is lateral. There is also the possibility of working
outdoors (Fig. 20).
The roller blinds are in textile material and opens/closes automatically (DALI
system) when the exterior illuminance is over 20.000 lx (Figs. 18 and 19).
Fig. 17. Iluminances nearby the workstations, on the 3rd floor, west building (on the left is 24th
July Avenue). Illuminances at 11.30 a.m. (dark blue text) and at 6 p.m. (red text). (layout was
ceded and adapted) [Author]
Fig. 18. Distribuition of lumi-
naires (ceiling) [Author].
Fig. 20. Outdoor on the 3rd floor.
(west building) [25].
Fig. 19. Lumi-
naires next to win-
dows and roller
blinds [Author].
Lighting Design at Workplaces: What Should Be the Concerns for an Architect? 579

The colours and finishings of surfaces, such as desks and cabinets are matt white,
and there are frontal screens in wood. The colour of the chairs are grey, red and green.
The floor is grey, the walls are white and grey (concrete). The suspended ceiling is
grey, but the real ceiling is painted in black, so the ceiling looks black.
4 Comparison Between the Case Studies
See Table 1.
Table 1. Comparison between the case studies. [Author]
Parameters Camilo Castelo Branco Street 24
th
July Avenue
Main Façade/Rear
Façade
WSW/WNW Sul/North
Distances from the
windows
Yes. 11.10 m, 9.60 m, 6.80 m,
5.50 m and 4.50 m
Yes. 4.66 m
Windows (height) From 0.70 m (height) to the
suspended ceiling
From floor to the suspended
ceiling
Illuminances near
windows (morning)
156 lx, 793 lx, 931 lx, and 1000 lx 1566 lx, 1188 lx, 967 lx,
1159 lx and 1191 lx
Illuminances distant
from the windows
(morning)
600 lx, 519 lx e 600 lx –
Illuminances near
windows
(afternoon)
649 lx, 349 lx, 696 lx and 618 lx 318 lx, 284 lx, 490 lx, 592 lx
and 399 lx.
Illuminances distant
from the windows
(afternoon)
500 lx, 483 lx and 500 lx –
Artificial lighting Direct, recessed, fluorescent,
aluminium reflectors, 4.000 K (cold),
IRC 85, suspended ceiling rectangles:
0.30 m (width) by 1 m (length)
Semi-direct, recessed,
fluorescent, frosted glass. No
data (colour temperature, IRC
and dimensions)
Distance between
luminaires/lamps
6/7 acoustic metal tiles East: 11.2 m, 25.8 m, 18.8 m,
18.8, 22.4 m and 14.1 m.
West: 16 m, 20.8 m, 20.8 m,
22.1 m, 22.1 m and 12.9 m
Angle of incidence
of the light at the
eye
0°–30° and 30°–45° Lateral
Colours and
finishings of
desks/chairs
White desks, frontal screens in
wood/black
White desks, frontal screens in
wood/grey, red and green
Colours and
finishings of
floor/walls/ceiling
Grey/white/white Grey/white and grey/black
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5 Conclusions
In both buildings, the distances of workstations are very far from the windows, for
example in the building located in CCB there are distances greater than 11 m.
Regarding the presence of nature views through windows, in both case studies there are
natural views, the building in the CCB has views to Eduardo VII Park and the building
on 24th July Avenue overlooks the Tagus River. Regarding illuminances, both have
less than the 2.000 lx, which are required for the non-visual system. The lighting
design is not concerned with the human needs, since fluorescent is appropriated to the
visual system and has no effect on the non-visual system. The correct angle of inci-
dence of the light at the eye should be between 45° and 90° to activate the ipRGCs, and
either of the case studies has it. The distance between the luminaires ignores the
workstation’s positioning on the open space, and it is clear, especially in the building
on 24th July Avenue, that the most important factor is aesthetics. As for the furniture,
desks are white and have wooden frontal screens, which give a more noble appearance
than the neutral of the grey floor, and white walls. In the building on 24th July Avenue,
the coloured chairs are a good choice, but the black ceiling is not the best option.
Nonetheless neither considers the non-visual needs of the workers.
6 Discussion
Lighting Design is much more than a layout or a corporate image, and is conceived by
architects most of the times, and that is why the article´s title begins with Lighting
Design and ends with Architecture. However, both (sometimes) are unaware of the
impact of light on the non-visual system in humans. The main goal of this article is to
give some clues and is an attempt to awaken the curiosity of architects, designers and
engineers on the non-visual system in humans.
Biophilia, for instance, is a good influence both in the mind (psychologically) and
body (biological and physiologically), as stated, since the mind influences the body and
vice-versa.
The non-visual system (circadian rhythm) is influenced by light and this should be
used in a positive way. The lighting system is not irrelevant, due to its spectrum, for
example, fluorescent light is, normally, in the green (a good option for the visual
system) and yellow spectrums, whereas the LEDs are blue light (spectrum). Blue light
has two sides, just like a coin, it could be good since it makes us more alert, focused,
less prone to SAD, on the other side (of the coin) it can be harmful for our eyes (blue
light hazard).
As for illuminance, more than 2.000 lx is biologically effective, less than that is
considered as biological darkness. However, it should be carefully used, because too
much illuminance at night, or late afternoon might unbalance our circadian rhythm.
Angle of incidence of the light at the eye is another crucial factor since the lateral
light or right above our heads are not the best choices, as already stated (Fig. 2).
Geographic location, sun´s position, seasons, the number of daily hours with
sunlight, weather conditions, time of the day (morning, afternoon and evening) and
built environment (surrounding) should not be disregarded.
Lighting Design at Workplaces: What Should Be the Concerns for an Architect? 581

Distance from the windows, especially when natural light is not enough for the
non-visual system (2.000 lx) should be compensated with artificial light.
Surfaces and furniture colours and finishings, are also important, since glare and
shadows are not welcome in our visual field.
Moreover, cultural and social background, individual preferences, pathologies, age
and the tasks performed are all factors that should be considered when designing a
workplace. Although, this article did not analysed all these issues.
In sum, Lighting Design is much more important than it seems.
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