The External and Internal Environments, including people within them, provide the stimuli for human reactions.
Discuss the role of buildings within this context.
During this discourse I seek to expand on Halls Proximic Framework of the human being to include
all layers of human space, right from the intimate aura that surrounds each one of us, through
areas of personal space to social and public spaces. Ultimately the building environment in its
various guises affects and is affected by the human being both on an individual level and also on
a collective level. I find the analogy of an onion with its many skins, helpful when applied to
the human being.
I touch on the various senses that aid us in acquiring information about our changing environments
as well as our memories and how the past has relevance and makes its stake in our futures. I expand
the idea of the Cognitive Map to include time as well as space and look a little more closely at the
work environment, where the disparate backgrounds of the people working together, brings new challenges
to the building designer.
I conclude with some thoughts on future development of living and working space and raise some
thoughts on how environments may even effect our belief systems and the larger social groupings
across the world.
The External and Internal Environments, including people within them, provide the stimuli for human reactions.
Discuss the role of buildings within this context.
The final yell of labour is replaced by the tinny squawk of a new born baby as it's wrapped in soft
towels and brought to suckle against the mothers breast. Right from the first perceptions of touch,
sight and sound within the womb we are subject to our ever changing environment and we learn to adjust
to the constant changes that occur around us.
The baby's wail of shock as it has to learn to fight for oxygen using air as the supply is an early
indication of the importance of the environment on our well-being. The moist 37.5 degrees of the mothers
womb is replaced by a air temperature drop of more than 12 degrees. The baby is no longer enclosed within
a warm, soft protective sack that muffles the loudest sounds and rocks it gently to sleep. Its senses
are attacked by the unfiltered clamour, bright lights and pungent odours that we take for granted.
The roughness of the towel and the crisp new nappy replace the soft comfort of the womb.
Research has revealed innate perceptual abilities demonstrated by human infants. They show significantly
more interest in human faces than in objects and that they show reluctance when approaching a 'visual cliff'
(an impression of a sharp drop on solid glass created by Gibson and Walk (Veitch(1), 1994). There is also
evidence to suggest that the infant recognises its mothers voice from when it was inside the womb. These
early building blocks of the senses are the starting point for the baby to begin to obtain its scale of
reality (Clements-Croome(1), 1997).
Hall developed a 'Proximic Framework' where he highlighted four distance zones characterising categories
of relationships; intimate, personal, social and public and related this to the way people make use of
space (Farshchi(1), 1997). I would like to apply a slightly different approach to looking at these zones
within the context of environmental effect. We can view the human soul as being surrounded by 'Layers of
Personal Space', akin to onion skins. In this context, each skin is dependant on, and in contact with the
skin underneath. I believe that using this picture we shall see how the human individual impinges on, and
is affected by, its environment, from the individual's most intimate 'skin' to the most public.
We all have an aura of energy surrounding our bodies, enveloping our senses, and thereby giving us the
initial messages necessary to interpret the world around us. This forms our 'intimate layer', or our
'first layer of clothing'. Our view on the world is shaped by our perceptions and experiences and the
social programming that has gone on before. Someone from a similar viewpoint may have very different
perceptions of an environment such as a dentist surgery. One person may have had numerous painful
experiences under the drill, the other may have had very little trouble with their teeth. Consequently,
one suffers stress as the clean disinfectant smell of a dentist surgery, the sound of high-pitched drilling
and the especially shaped smooth backed dentist chair under the bright directional lamp brings them out in
a cold sweat and fill them with dread. The other sees a visit to the dentist merely as a minor inconvenience.
The Gestalt point of view is that behaviour is rooted in the perception of stimuli rather than the
stimuli themselves (Veitch(2), 1994). 'One man's meat is another man's poison' in the world of stimuli.
Our perception of stimuli is very important since our senses are constantly bombarded from all directions,
even in relatively simple environments, so much so that we cannot hope to take it all in. We spend our
lives fighting to process the constant stream of stimulus information in order to get our bearings and at
various stages to influence these stimuli to our advantage.
When and where do we begin to influence our environment? Who can bear an infants cry? Not only does the
baby's mother begin to lactate at the cry of her child but other mothers with babe in arms are known to as
well. The baby says 'I am hungry', 'I want a cuddle' and consequently creates an environment full of noise.
The instinct to cry forms a very useful tool for attracting attention and for communicating desire for things
other than food as the infant grows older and wiser to its effect. The infant learns an element of control
within this over-stimulating world.
Our 'personal space' is made up of several skins such as our clothing, our bed and our 'personal room'.
During the eighties organisations such as 'Colour Me Beautiful' flourished dramatically as realisation dawned
of the importance of the effect of colours in dress. Using your 'second skin' you can affect the visual
environment for other people. furthermore you can induce varying emotional responses from those around you
and your environment is in turn changed as they respond to you.
In an ever more crowded city environment it is evident that dress code, fashion and style has far more
importance to the city dweller. Perhaps the forced close proximity of other humans increases the desire
to impinge our individuality by way of dress code. The captive 'audience' in a crowded tube is bombarded
by the smells and physical contact of other individuals, buskers taking the opportunity to make some money
and advertisers plastering the walls of tube trains and stations with posters. In a crowded environment
the Cognitive Map suffers (see Appendix A) and eye contact is less (Veitch(3), 1994) - p245).
As a reaction to this bombardment, it is notable that the customary reading of newspapers to isolate oneself
from the crowded environment is augmented by the use of personal stereos, particularly by the young. Personal
environments are thus created, where there is control of what is seen and heard. I found from my experience of
working in a factory environment, that having a personal stereo greatly enhanced my time, as I found some relief
from boredom and the continuous noise of the machines. Many within the factory protested fiercely when management
tried to ban personal stereos. The ban amounted to an attempt to take away control on one's personal environment.
It has been seen that people experiencing electric shocks experience less trauma if they have more perceived
control (Veitch(4), 1994).
Another personal skin is your own room, be it a bedroom, study or student accommodation. If, as a child
you always had to share a bedroom with siblings then you would appreciate more than most the thrill of your
first room on your own. Perhaps as a student or your first rented room. As a student you have very little
funds to have much impact on your environment and your expectations for where you live start from a fairly
base level. Consequently, after a few weeks in your digs you adjust and the place, no matter how rough,
becomes home. We adapt and make the environment an extension of ourselves, or another personal skin
This room space invariably contains all that is intimate and dear to you; possessions, bed, clothing and
the decor. The bed and the bedroom could be considered as another skin in this onion. The bed is where
the human is most vulnerable, when asleep, and most intimate, during sex. Sex is particularly interesting
as it is one of the most fundamental opportunities for the human being to peel back the numerous onion skins,
revealing as close to the soul as is dared. The ultimate in intimacy.
Birds build nests, badgers build sets, termites build complex air-conditioned dwellings, humans build homes.
The home forms another distinct skin, still part of 'personal space' but it begins to form an environment for
close social interaction. A growing family, young children learning to relate with their siblings and parents,
the invitations for close friends and family to stay for short periods and parties for friends and acquaintances.
The human home forms an anchor point for a close knit group such as a family to begin to build the beginnings of
a social skin layer on the personal interacting skin(s) that inhabit the home.
The home is where there is still a large degree of control on your environment. You can open windows,
light fires, turn up the central heating, have a shower, change your clothes when you wish to. If a small
knit group inhabits the home, then there is some negotiation to carry out as a consensus is reached on the
how the environment should be.
Moving house is generally a very stressful time. Rarely, in western society, does the human build its own
home. Homes are commonly built en-mass to satisfy generally perceived needs, you will be hard-pressed to
find this within the animal kingdom. Having moved house myself recently, it was interesting to find that
although the financial and legal process was stressful in itself, there was also the factor of environment
change which was disconcerting. The previous occupier had a different idea of cleanliness, decor and general
standard of up-keep. The initial urge to stamp one's own tastes and influence upon the new home environment
was very strong. Re-decoration occurred with as much enthusiasm, funds and time as possible, the smell of
new paint became a neutral starting point from which to impose our own family smells and to cover the previous
occupier's smells. Interestingly, a few months into the new occupation, and much of what was not completed
during the initial surge of activity, remains incomplete, and the urge to immediately eradicate all traces
of the previous occupier diminishes over time.
I have now become more accustomed to my new home surroundings. Together with the realisation that these
surroundings are now my surroundings, reinforced by the daily interaction with the new home environment
both visual, acoustic (central-heating and to some extent outside noise from neighbours, wildlife and traffic)
and olfaction, the environment has slowly become home. The major change has now been assimilated by my
psyche and I am no longer in distress. The negative stress caused by moving home for the elderly can be
catastrophic for them.
An interesting experience that we have had since moving our home is our reaction to the now much larger lounge.
The lounge has a room adjoining it which is much smaller and very similar in size to the lounge in our previous
home. We have almost unconsciously made this smaller room our main living area, and to get to this room we run
across the expanse of the large lounge almost like frightened rabbits scurrying to find the comfort of their
small hole. The feeling of space has dramatically changed for the social centre of the house and it will take
us a while to adjust.
An invasion of this personal space, such as a burglary, has a profound effect on people. It has often been
likened to rape, which is the ultimate invasion of not just the personal skin layer but the intimate skin so
As we move out from our intimate and personal skin layers we mingle in the social arena within the street,
village and district communities. The local school, pub or library become environments where you no longer
have complete control on the effect of the people within them or the buildings themselves. These environments
form part of our social space.
In our highly visual age, we give much attention to visual input (Veitch(6), 1994). An expression such as
'Seeing is Believing' and even the cynical expression 'Believe nothing you hear and only half of what you see'
gives primary credence to sight over other senses. The building environment, however, is a multi-sensory
experience (Clements-Croome(1), 1995). Certain buildings remain impregnated in your mind, the school gymn
with its smells of sweat and plimsoles, the dry feel of the town library, the dusky smell of the dark local
church, a charity shop with its camphor and old clothes odours (Clements-Croome (2), 1997). My memories are
most clear at traumatic times of my life, my first day at senior school remains vivid in my mind. I was
overwhelmed by the size of the buildings, the history behind them and the size of the campus. My senses
were on overload as I struggled to make sense of the new environment. (Veitch(7), 1994). These memories
play a large part in our interaction with present situations as we draw on our cognitive base to supplement
our sensual information.
I propose that the cognitive map can be extended to cover not just our position in space but also where we
stand in time. Note the family arguments that commonly occur as the possessions of a lost loved one are
shared around. The items themselves are often not worth a great deal in pecuniary terms, but the memories
associated with them help keep alive the good memories of the deceased family member.
As we move in our social spaces and into public space, the effect of the environment becomes ever more
crucial, as we have virtually no control on public space whatsoever. How often are our memories exploited
in marketing? The resurgence of the old television programmes and new films such as Batman and Mission
Impossible have been used to exploit fond memories we have, giving us a warm feeling of familiarity as these
products point to a 'landmark' in our Cognitive Space-Time map. Whole industries are geared to using
advertising hoardings, piped music and video walls to send out messages of familiarity to soothe the concerns
associated with being in public space, but with twists of innovation to arouse the interest.
The television is one golden opportunity for marketing agencies to influence the personal space. Adverts
depicting Steve McQueen driving the new Ford Puma have sixties style music in the background.
In the same way that negative experiences can affect your perception of a particular environment, e.g. a
study room (Veitch(8), 1994) so a positive experience can colour your view on a new environment. A positive
anchor point such as a popular song can help to influence your perception of the product being sold. In the
recent Channel 4 series 'Shop 'til You Drop', it was revealed how that different styles of piped music influenced
the behaviour of shoppers; contemporary music encouraged the younger age groups (with more money to spend) to
spend more time in a 'club' style atmosphere.
Certain environments vary in stress dependant on expectations (Veitch(9), 1994) and crowding can be seen as
something positive, a crowded soccer stadium or a packed pub are more attractive than their less full counterparts
(Veitch(10), 1994). Recent tussles at soccer grounds, such as Old Trafford (WWW1), about standing up could well
come from the past expectations of being able to stand at football matches and frustration at no longer being
able to express as much involvement due to council rules.
We will now examine the workplace which is an unusual form of public space where people from quite different
personal and social environments (or skins) are forced together.
Traditionally, the place of work has been intrinsically linked to the personal space called home and the
social space called the village. Commonly, people travel a long way to work in a totally unconnected
environment form home, along with others who come from very diverse range of homes. The work environment
provides a challenge to create a building capable of providing a productive environment for this large
range of social types (Clements-Croome (2)). There is an inverse relationship between stress and productivity (WWW2).
Your place of work is particularly important for your well-being. Studies have shown the importance of daylight
in minimising depression (Veitch(11), 1994). Wilkins showed that good daylight improves health
(Clements-Croome(1), 1995) and absenteeism is less as a result (Wilkins (1), 1993). It is interesting to
find that the etymology of the word comfort is in the Latin 'com' (meaning 'with') and 'fortis' (meaning 'strong')
(Concise Oxford Dictionary). As well as 'making comfortable' meaning just physical and mental well-being,
it also has its roots in 'strengthening'.
The Yerkes-Dodson law (Clements-Croome(1), 1995) demonstrates that optimum arousal level is good to aim
for, thereby avoiding situations as faced by nurses suffering from the 'oppressive visual environment' of
intensive care (Sutherland(1), 1994). Stressors within the environment can come from a number of sources;
noise, vibration, lighting, hygiene, poor ventillation and temperature extremes. People take less informal
breaks when the environment is more comfortable (Clements-Croome(3). Exercise is seen as a way of reducing
the negative effects of stress (Sutherland(1), 1990), and companies such as Xerox, in Marlow, have seen fit
to include a gymnasium within the building.
There are other sources of stress related to management and other people. These include crowding, workload,
long hours, risk and new technology. Bad management resulting in poor communication and poor relationships
has been shown to adversely affect performance and well-being in men (Sutherland(2), 1990). The other side
of the coin is that good relationships lead to a more satisfied workforce, it is clear that there is a strong
psycho-social factor to the environment. Someone may wish to turn down a thermostat in order to please someone
else rather than because they themselves were warm (Veitch(12), 1994). How others see us and respond to us is
very important. Non-smokers have been shown to have less liking for people who smoke in their presence
(Veitch(13), 1994) and noisy environments have been shown to reduce peoples helping responses (Veitch(14), 1994).
Feng Shui (meaning 'wind and water') (Too, 1996) consultants are now becoming more commonly used in building
design as the business world becomes more convinced of the benefits of creating environments with good Feng
Shui thereby improving opportunities for growth, attracting customers, raising profits and the company profile
within the community. The origins of Feng Shui are in shaping the topography of the earth, mountains and valleys
by wind and water. Now Feng Shui is used to shape business environments as it becomes clear that good
environments have significant impact on productivity.
When designing for the environment all personal space layers of the individual need to be taken into account.
In addition, the way individuals interact with each other to form the various social groups also needs to be
considered. Perhaps designing only with a group of people in mind, only serves to isolate many individuals
(Clements-Croome(2), 1997). There is no such thing as an average person. Each person has an effect on or is
affected by, to a greater or lesser extent, each other. In addition, each person's perception of their environment
is different and varying over time, depending on the states of each 'onion skin'. Kurt Lewin declared that
Behaviour is a function of the Person and the Environment (Veitch(15), 1994)
Also borne out in the Markus model (Clements-Croome(1), 1995), there is a unique relationship between a person
the building and the environment (Clements-Croome(1), 1995). People do adapt to their environment, and that must
not be forgotten, however, some can adapt more easily than others. We need to build intelligently in order to
cater for a broad range in adaptability e.g. minimise unnecessary change for the elderly.
What about the environment in say, a hundred years time? We could be in the early throes of populating the
inner solar system. In one respect by necessity, there is likely to be more stable environments, such as
Ecospheres (WWW3 and WWW4) with less general variation that we find on our planet. Ecospheres that are being
designed for harsh environments could well be expansive on the moon (especially with the recent discovery of
substantial ice deposits on the moons polar cap). It is my guess that there will be significant inroads made
into personal environmental control on the advanced lines of Johnson Controls personal desk environment (WWW5).
Complex environments pose a subconscious threat since all our senses cannot take everything in. Perhaps
simple environments are more calming, empty beaches, monasteries (Veitch(16), 1994). What is clear is that
minimising negative stress is highly desirable. You can get away with higher temperatures if you provide
some individual control, or perception of control.(Veitch(17), 1994) and intelligent design of school environments
which are geared towards new pupils could minimise unnecessary distress caused by children getting lost.
I have attempted to draw an analogy of the human personal space layers being like the layers of an onion. We
have considered the human soul as being surrounded by a sensual intimate aura, then personal clothing, the bedroom,
the home and then movement into the social space of the street and town. Public spaces provide the least security
and can have lasting impressions. The work environment provides a peculiar mix of people working closely within a
similar environment, and this alone brings its stressors. Of course, the human environment does not stop there, our
collective influence stretches far further than our town, even our country. Things that happen on the other side
of the world can affect us, the crash of the 'Tiger' economies, the Gulf War or rain forests being destroyed in
order to graze cattle for our hamburgers. Perhaps that is why there is an ever-growing movement to protect our
global environment as we become more sensitive to the collective effect that we have on it. It is clear that
environments affect whole populations, indeed it has been shown that prolonged stress reduces population (Veitch(18), 1994).
The increase in travel is responsible for the conglomeration of cultures. The United Nations is seeking to
expand, the Europe is inexorably becoming more federal. It is popular fantasy, now that the Cold War has ended,
that we may eventually have to face an extraterrestrial enemy. Perhaps Saddam Hussein is our last great enemy,
is society becoming less tolerant of the great tyrant? The seeming closer proximity of our neighbours forces us
to deal with the tyrant rather than be tempted to turn a blind eye, as in the days of Hitler. Perhaps it is true
that 'Environment sets the stage for the development of cultures' (Veitch(19), 1994) and ultimately, maybe,
environments shape our belief systems! In the recent documentary 'The Sound of the Carceri', the Cellist Yo-Yo Ma
uses his interpretation of Bach's music and three-dimensional graphics to create a virtual space. The music is
recorded in such a way as add the feelings of volume and space to Piraneses etchings of Carceri prison. The
architect Moshe Safdie stated that 'Graphics and rendition are not Architecture', and he is right, however, we
create our own interpretation of the space we inhabit via the messages we receive from the most public of our
space layers to the most intimate aura that surrounds our senses.
Appendix A - Cognitive Map
We all build 'Cognitive Maps' (Veitch(20), 1994). You may perhaps have experienced waking up in the night, in
a strange hotel room, with the feeling of panic having no bearings of where you are. You have no cognitive map.
Milgram proposed that the Recognisability of an area was a function of the areas Centrality to population flow and
its architectural or social Distinctiveness (Veitch(21), 1994). In a similar vein, Lynch asked people to draw sketch
maps of environments which he analysed for common elements. Evidenced was the fact that people included five elements
within their 'Cognitive Maps'; paths, edges, districts, nodes and landmarks. Individual maps differ from each other
and are always full of 'mistakes' when relating to actual physical maps due to the varying perceptions and experiences
of the individuals. In environments new to the individual, the senses are supplying new information at an overwhelming
intensity causing stress. Over time, the brain develops mental images of the environment and the cognitive processes
start to dominate our perception of the environment rather than relying purely on our senses (Veitch(22), 1994).
Without a Cognitive Map we no longer feel in control. The child just starting a new school has to work hard to find
out where the next class is, where is the dining hall, the changing rooms etc. Until the child forms their own cognitive
map they are under stress and these first few weeks can often have critical and lasting effects on the perception of
this new environment.
- Clements-Croome, Derek(1), 1995, Specifying Indoor Climate Data.
- Clements-Croome, Derek; Kaluarachchi, Yamuna; Baizhan, Li(1), 1997, What do we mean by productivity?, pp. 5.
- Clements-Croome, Derek; Kaluarachchi, Yamuna; Baizhan, Li(2), 1997, What do we mean by productivity?.
- Clements-Croome, Derek; Kaluarachchi, Yamuna; Baizhan, Li(3), 1997, What do we mean by productivity? pp. 14.
- Farshchi, Mahtab, Akhavan; Fisher, Norman(1), 1997, The Emotional Content of the Physical Space, pp. 5.
- Sutherland, Valerie J & Cooper, Cary L(1), 1994, 6. Stress in the Work Environment, Rose, pp. 143.
- Sutherland, Valerie J(1), 1990, Managing Stress at the Worksite, Current Developments in Health Psychology, Bennett, Spurgeon & Wenina, pp. 323.
- Sutherland, Valerie J(2), 1990, Managing Stress at the Worksite, Current Developments in Health Psychology, Bennett, Spurgeon & Wenina, pp. 322.
- Too, Lillian, 1996, The Complete Illustrated Guide to Feng Shui, ISBN 1-85230-882-6, pp. 1.
- Veitch(1), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 84.
- Veitch(2), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 18.
- Veitch(3), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 234, 239, 242-245.
- Veitch(4), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 138.
- Veitch(5), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 260.
- Veitch(6), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 79.
- Veitch(7), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 85.
- Veitch(8), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 106.
- Veitch(9), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 119.
- Veitch(10), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 244.
- Veitch(11), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 162-163, 167.
- Veitch(12), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 109.
- Veitch(13), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 192.
- Veitch(14), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 220.
- Veitch(15), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 7.
- Veitch(16), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 85.
- Veitch(17), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 22.
- Veitch(18), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 124.
- Veitch(19), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 17.
- Veitch(20), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 90.
- Veitch(21), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 91.
- Veitch(22), Russell & Arkellin, Daniel, 1994, Environmental Psychology: An Interdisciplinary Approach, Prentice Hall, ISBN 0-13-282351-9, pp. 111.
- Wilkins, Arnold J(1), 1993, Health and Efficiency in Lighting Practice, pp. 124.
- WWW1 - http://www.sky.co.uk/manu/
- WWW2 - http://www.cinenet.net/biofit/Pages/stress.html
- WWW3 - http://techtransfer.jpl.nasa.gov/success/stories/ecosys2.html
- WWW4 - http://www.eco-sphere.com/care_manual.html
- WWW5 - http://www.johnsoncontrols.com/cg/PersEnv/pe_home.htm