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IMPACT OF ARTIFICIAL LIGHTING ON THE PERCEPTION AND USAGE OF INTERIOR SPACES

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Abstract

The designer can create the most eloquent space, crafted in exquisite detail using finest
materials in the most gorgeous colours, but, without light, he or she has wasted time, effort
and money. Light and the effect of light are key to the enjoyment and functional successes of
spaces. The way the light impinges on the highpoints of surfaces, and the shadow created by
its absence, allow us to perceive form and texture. It is the light that allows us to discern
differences in colour and tone. The painterly use of artificial light, experimented in this
report, can be employed by the Architectural Designers to create a mood appropriate to the
particular brief, space and retail interiors.
Until man learnt to artificially replace it, the fundamental source of light was the sun
and in many respects sunlight remains the platonic ideal of light : its varying strength, colour
values and direction bringing liveliness to the environment, changing through the day and
from season to season.
It would be an unusual building, with unusual inhabitants, that was capable of using
natural light alone, and virtually all buildings with which interior architects work employ
artificial illumination to replace or supplement natural light. Over the centuries tapers,
candles and oil lamps have given way, first to gas light and ultimately to the various forms of
electric light. Each had a particular character, qualities and problems. In the design of interior
environment we are often endeavouring to replicate the positive aspects of the system and
products while minimising or overcoming the shortcomings. This is as true as lighting system
of any other. By identifying the needs and developing a lighting design ethos that marries the
requirement of space, activity and mood, it is possible to specify a lighting system that at one
extreme may mimic the intimacy of candlelight and at the other provide the lighting levels
and even distribution of different retail product category, with ever conceivable variant in
between. In fact with the different combinations of light it is possible to create lighting that
can modify the mood and the capabilities.

The objective

In architecture, light is tremendously vivid and manifold. Intelligently positioned and well-
dimensioned, light is able to generate a terrific intensity. Light can stir up emotions and help
bind them to loved experience. When it gets dark, human beings undergo a change of mood.
At these times good light is always in demand. The art of lighting design consist of the ability
to bring out even extreme and unusual features. Beauty and harmony makes an impression,
the same as inevitable conflict and the grotesque. Light must appeal to everyone, but it must
also have a situational effect for individual, couples or groups. Good light continually
rewards the fine line between harmonious variety and sharp contrast.

Why Artificial lighting?

Artificial light has made much of human development possible. Since the discovery of
fire, light plays a central role in our lives, extending our hours of life, creating mood and
atmosphere in our homes, and increasing our productivity.
Since the rising concerns in the last century about the electricity use of traditional
incandescent light bulbs, the mainstay of our post-industrial lighting solutions, there have been
many alternatives brought to market. Some of these are excellent replacements for the standard
lightbulb in most cases but others are not such great alternatives.

History of Artificial Lighting

The Evolution of Artificial Light, shows how artificial light and its twin invention, electricity,
have in one way or another shaped everything that we have become.
The artificial light follows the path of this catalyzing technology as it winds it way from the last
Ice Age into present day. Early humans using stone lamps for painting the walls at Lascaux, to
the whaling trade as it arose to supply the world with lamp oil, to Edison’s Menlo Park and the
dawn of modernity, to the massive power grids of today, a story of evocation begins to emerge.

Fluorescent tube

Fluorescent tubes are the main form of lighting for offices and commercial buildings. They are a
form of gas discharge lamp, and are formed in a long thin glass cylinder with contacts at either
end that secure them to the fitting (or luminaire) and provide the electrical connection. The tube
contains mercury vapour at low pressure, and the inner wall of the glass is coated with a
phosphor that reacts to ultra-violet radiation. When electricity is passed through the vapour it
emits UV radiation that is converted by the phosphor to visible light. The most efficient
fluorescent tubes are the T5. With a smaller diameter (16mm) than earlier tubes, these can
achieve a luminous efficacy of up to 104lm/W.

Light Emitting Diode (LED)

There are a few different LED types. We all know LEDs from the thousands of uses they perform
as tiny signal lights on our stereo, phones, and other electric equipment. They are mostly
semiconductor devices that operate on low voltage DC currents mostly, often requiring an
adapter. Because they are semiconductors, LEDs are quite sturdy and less likely to break if
dropped or due to harsh conditions compared to other lamps. Their life span is very long, some
are rated up to 50.000 hours.
LEDs used to only be available in red, green, yellow and white, with the blue type only
becoming available much later. These signal LEDs (image below) are not suited for general
lighting applications, because they are not very energy efficient and their spectrum tends to be ill
suited for general lighting.

Halogens

Halogens are incandescent lights where the gas chamber is filled with a halogen gas type,
allowing the light to operate at higher temperatures, last a bit longer, and be more compact.
Halogens tend to be somewhat higher in performance than normal incandescents, with
slightly higher efficiency, and a longer life span, but typically cost more. Halogens are also made
in more accurate production processes that allow very specific models and light spreads to be
made. Therefore, high quality spot lights tend to be halogen lights. Because of their excellent
color rendering and spectrum, halogens have been the lamp of choice for demanding light
applications in the home, office, laboratories and elsewhere.

Energy

If we understand that electromagnetic waves are a form of energy, we understand that
radiation in the infrared and ultraviolet ranges also contain energy, eventhough we cannot
perceive them with our eyes. Infrared is generally perceived as heat, and ultraviolet as
invisible radiation that may damage our health (UV radiation) but is also used for certain
useful purposes by other animal species, such as by bumblebees for navigation. It should also
be said that we don't fully understand all the effects of the electromagnetic spectrum on
biological life. We do know that it's of vital importance to almost all living things and that
life on earth has evolved in iteraction with the spectrum of our sun.
Why is this important if we want to learn about artificial light sources? There are
various clues to be found in this as to the effects of various light fixtures that may not be
easily explained from a purely technical perspective. In addition, understanding that visible
light is just a subset of the electromagnetic spectrum is important to understand if you're
looking for light sources that both perform well and are energy efficient.

Lighting level for different human comfort

Lighting an environment is often a complex task principally considered during the design
stage of the building (by architects and interior designers). However, lighting should be designed
for the tasks that individuals are carrying out within that environment. Guides to lighting can
seem very complex, technical documents. However, employers can take some simple steps to
ensure people have adequate lighting to carry out their tasks.

Balanced Luminances

The luminances of surfaces we perceive are caused by the reflected luminous flux that
reaches our eyes. The luminance values depend first, on the absolute level of the illuminance
and second, on the surface’s reflectance value.
If a certain level of illuminance is recommended (rated illuminance), a certain amount of
luminous flux is necessary. Thus the luminance can only be modified by changing the
reflectance value of the surface, which means the replacement of materials.
Thus, the lighting designer is able to achieve a balanced luminous environment within the
field of view by choosing materials with certain reflectance values. Reflectance values
mostly correspond with certain colours of surfaces. That means the luminous environment
can be adjusted by changing the colour of walls, ceiling, floor and desks. This is one of the
many examples that demonstrate the close connection between lighting designer and
architects.

Colour Rendering

Colour rendering is a general expression for the effect of a light source on the colour
appearance of objects in comparison to their colour appearance under a reference light
source. The latter is very important concerning colour rendering. The colour appearance of
one body (surface) can be changed completely by using different light sources. Thus,
daylight is used as the reference source of high colour temperatures; incandescent light is
used as the reference source of low colour temperatures.