1- a definition of Light
All sources of light have their own particular qualities, some of which are the result of the light source itself and the some the result of external influences, such as the weather and the landscape.
The light from the sun, for example, is constantly changing, depending on the time of day, the time of year, the weather …etc
The quality of any light (whether natural or artificial), can be defined in three simple ways:
a- Tone:
The tone of a light is defined by its colors temperature. The temperature of light is synonymous with its color, in the sense that they are both the product of a specific wavelength. The primary colors of natural light make up the spectrum of colors that can be seen when the light is split by a prism; at one end of the scale is ultraviolet (the blue end) and at the other is infrared (the red end of the visible spectrum).
We light we see is a mixture of all these and is described as “white”, but all light sources have their own color; meaning that they emit a distinct wavelength pattern, depending on what they are designed to do.
b- Intensity:
The brightness of the light is fundamental to the quality of the atmosphere in a room. That is not to prelude the use of very bright lights, and if used, these lights are to be carefully controlled. Generally, a number of dim lamps will create a more interesting atmosphere than a single bright lamp, even if they add up to the same amount of light. So basically the intensity is not only the physical amount of light in a certain space, but also how this light is translated in the space.
c- Focus:
Whether the light is direct or not is the result of exterior influences on the light that is emitted from the lamp.
The “bulb” of the standard lamp is frosted and throws a diffuse light all around, producing a bland featureless light. However, if a crown-silvered lamp is combined with parabolic reflector, the design diffuses a very tightly focused beam, producing a dramatic light capable of giving life and shape to a room.
The number of designed lamps is incredible and each of them has its own controlled width of beam, and different lamps are to be used in different places and serve various functions (emphasis, illumination, etc)
d- Natural effects of light:
The atmosphere we experience in the outside world in the combination of the tone and the contrast produced by the conditions. We can begin to study those natural conditions by analyzing the tone, intensity and focus.
The quality of sunlight at noon in the Sahara desert is harsh and bright, with intense shadows. By contrast, in a deciduous wood on a wet day in the northern hemisphere, the light is muted and soft with very little obvious shadow, the whole effect being diffuse and vague.
Humansʼ mood is strongly influenced by these conditions, the feeling tend to vary in a certain way about a place or scene, depending on the quality of the light.
The search for understanding the relationship between light and mood was of primary importance to the impressionist school of painters at the turn of the century. They sought to represent light with pigment, capturing atmosphere through color. Studying their work has brought important information about the color of light and its effect on mood.
e- Light as material:
Architects thoughts always seek the material of finished product while they work out the puzzles of the volume or proportion of space. Different materials, including stones, brick, steel, glass, wood, tile, plaster, paper and cloth render different qualities in architecture. Light is an equally and sometimes more influential element in determining the result. It can even highlight or damage the value of architectural materials themselves.
Lighting fixture is an important tool for architectural lighting design that distinctively offers specific function. Each fixture has a different purpose according to the architectʼs intention. Be it spots or lamps or chandelier, these fixtures are the architectʼs accessories to producing the space.
However, the fixtures should stay behind the scene, the goal of light is to create a miraculous situation whereby the right amount of light is floating in the air comfortably.
The ideas for lighting design usually do not come out of the blue. Because architecture is a mean of various space functions, a function of light is also hidden for each of these segmented spaces. Liberal ideas full of creativity should be employed after thoroughly examining how the space should function.
2- effect light has on mood and psychology
“Light affects our bodies in two ways. In the first, light impinges on the retina of our eyes and, through our vision system, affects our metabolism and our endocrine and hormone systems. In the second, it interacts with our skin by way of photosynthesis and produces vitamin D. Daylight serves as a catalyst for the secretion of hormones from the pineal gland namely serotonin and melatonin.
The level of melatonin determines the energy and activity levels in our bodies. At darkness or low light levels, melatonin secretion increases and drowsiness occurs. Daylight suppresses the production of melatonin and fosters an alert state of mind by secreting serotonin. People who live and work in window-less environments or in places lacking adequate light may be at risk of having their internal clock continually disturbed. Melatonin is an important anti- oxidant and can neutralize some agents. Serotonin, a hormone first discovered in 1933, is the neurotransmitter identified in many psychiatric disorders. During long periods of high stress, serotonin is used up, exceeding its replenishment rate. Prolonged stress lowers serotonin levels in the brain and a stress-induced depression may take place. The less serotonin available in the brain, the more severe is the depression and related symptoms.” (1)
So light has a direct effect on our mood and feeling, from a scientific medical point of view. Light acts on the production of cortisol, serotonin, and melatonin, three important hormones that affect our internal clock and our mood states, among many other effects. It is important to keep these hormones in proper balance. Low levels of serotonin (the daylight hormone) cause depression. Light therapy, be it artificial or natural, has been found to be an effective antidepressant but only when the light is bright enough.
Light not only affects the psychological state of the person, but also has a direct effect on what he feels in a certain ambiance.
(1) Mohamed Boubekri; Daylight, Architecture and Health: building strategies, England, Elsevier (Architectural Press) 2008
An architectural space accompanied by a satisfactory function of light has the power to move people. The crux of architectural lighting is how it can cater not only to the biological, but also to the psychological needs of humans. The way architectural spaces are perceived generally vary from a person to another, but there is something known as an emotional impact, which is rather common among people. However, different studies have shown that the light color and intensity may affect people differently according to their age and gender: a study showed that young adults (of around 23 years old) preserve a negative mood in a warm (red tones) atmosphere, while older adults (65 yeas old) the cool (blue tones) conveyed the same negative effect when it came to cognitive performances.
Light, its color and intensity, vary according to the function of the local it is in. Thus, a hospital room, a classroom and a living room of a residential home should have different lighting whether it was artificial or natural (variation of opening types and spaces). Hence, Light is often used by architects as a metaphor, a mood-giver or a carrier of a meaning in and of itself.
The chapel of Notre-Dame-du-Haut at Ronchamp, France, by Le Corbusier is a boldly expressive free-form structure in which the symbiotic association between the form and the interior natural light identifies the essence of the building, making it the central element of the design concept. Through irregularly sized and shaped windows piercing the southern thick masonry wall of the chapel and from three light towers emerging through the roof much like wind catchers, light enters the space from multiple directions, bouncing off richly textured surfaces, and through colored glass that imparts unequalled poetic and spiritual qualities that have made the building one of the icons of modern architecture.”
Notre-dame-du-haut Chapel, Ronchamp, France
In the Chapel of Light by the Japanese architect Tadao Ando in Japan, light enters from behind the altar through a cruciform cut in the concrete wall that extends vertically from floor to ceiling. Light emerges through the crucifix as an abstract and universal event in contrast to the darkness of the concrete wall. The effortless simplicity of the space is contrasted only by the intense brightness of the luminous crucifix, making it the centerpiece of the chapel and of the spiritual experience sought by those who frequent it.
The effect of light on architecture this became a main concern to researchers, who started looking into the relationship between light and the mood of the occupants, not only in religious places, but in any social place, because anywhere, a human experiences mood changes according to dramatic change in light.
Psychologists and behaviorists believe that even in places where the change in lighting is not as dramatic, small changes in light may also affect a
personʼs mood or his emotional state. Apparently, the presence or absence light can produce a positive or negative effect.
The sensations that come along with good lighting are excitement, alertness and dominance. However, with poor lighting comes dullness, boredom and submissiveness. These states affect the social behavioral responses of the occupants and their ability to make proper decisions. When people are in a good mood, they tend to perform better in a work place and vice versa.
Most research on the effect of light and mood has focused on the artificial electric light. Unlike electric light, daylight is a more difficult field to study due to its dynamic and constantly changing aspect and its properties that are not static (as are those of artificial light). This changing character of daylight that varies from one minute to another makes experiments rather difficult, however there is a general natural preference for daylight over artificial light. This could be related to its spectral quality (the spectrum of daylight being the fact the white daylight is in fact the compilation of 7 colors – those of the rainbow) that triggers hormonal and physiological progresses. These progresses affect our psychological wellbeing. That however is not a proven fact, but whatever the reasons are, the fact remains that most people prefer natural lighting to artificial one.
The individual impressions of a space depend on the relationship of surfaces that are lit to those left in the dark, and on the focus of the surround or background, i.e. the emphasis on a space or another.
It is through the wits of the architect that the manipulations of light, brightness and contrast, focus and color, will give the desired emotional impact of an interior, though different degrees of stimulation.
The degree of brightness contrast evokes emotions in the same way as background music. It affects:
• The performance of task
• The behavior of people at work or play
• The amount of containment and pleasure, and emotions in general.
This brightness and contrast hence affect the way the person perceives the architectural space and how this space will affect him.
a- Brightness contrast:
Low contrast environment, everything is of equal emphasis
Mid contrast environment, combination of emphasis
High contrast environment, high bright and dark areas
Very high contrast environment – extreme high bright and dark areas
b- Subjective impressions
These are 6 different ways to light the same space and see how light different effect and the feelings/impressions it conveys to the occupants.
Picture 1: direct lighting on the table gives a strong contrast, is too harsh for lighting faces and It gives a strong impression of confinement and haziness.
Picture 2: shows lighting on all the walls, with low intensity. This lighting promotes the impression of spaciousness and increased height, at the same time gives a pleasant impression to the occupants of the room.
Picture 3: lighting of cove above, low intensity. This lighting is pleasant for near and distant faces and promotes a quiet impression.
Picture 4: direct lighting on table and lighting of small wall. It promotes a relatively strong feeling of pleasantness and gives the impression of length to the room.
Picture 5: direct lighting on table, and lighting of cove above. It gives a soft subdued effect and is pleasant for near faces, it also promotes the feeling of spaciousness.
Picture 6: lighting of cove above, and lighting of walls flat, shadow free. It gives a strong feeling of pleasantness and clarity and promotes the spaciousness of the room.
Other types of subjective impressions are shown below:
Impression of spaciousness: the room appears larger or smaller.
Impression of perceptual clarity:
the room appears public or private.
Impression of
pleasantness: the room appears friendly or sociable.
c- Degrees of stimulation:
Environmentalists use the terms High-load and Low-load to describe the degrees of stimulation or arousal. The more stimuli that must be processed by a person, the higher is the load.
Environments that are complex, crowded, asymmetrical, novel, unfamiliar, surprising or random are High-load, where as environments that are simple, symmetrical, conventional, unsurprising and organized are Low-load. High levels encourage participations and increase enjoyment where as low level help a person feel contented, comfortable, focused and relaxed.
Although individuals react differently to the same environment, there is a high degree of similarity in peopleʼs reactions to light.
3- effect light has on space
Light plays a central role in the design of a visual environment, the architecture, people and objects are all made visible by the lighting, since it is what enables “what we see”.
Our perception of architecture will be influenced by light:
• Light defines zones and boundaries
• Light expands and accentuates rooms
• Light creates links and delineates one area from another
The challenge of a qualitative lighting design is to develop a design concept that combines the technical and aesthetic requirements of complex guidelines.
a- Forming functional zones
Distinct contrasts between individual zones and their surroundings remove them from their special context, whether itʼs with the use of natural daylight (windows) or artificial light. Also the same technique can be used outside to form exterior functional zone, or inside, to form interior ones.
Interior:
exterior:
b- Defining spatial borders Horizontal
floor illumination emphasizes objects and pedestrian surfaces.
Indirect lighting of a ceiling creates diffuse light in the room with lighting effect being influenced by the reflectance and color of its surface.
Examples of defining horizontal spatial borders
Vertical:
• Vertical borders are emphasized by illuminating wall surfaces.
• Uniform light distribution emphasizes the wall as whole.
• Bright walls create a high level of diffuse light in the room.
• Vertical illumination is used to shape the visual environment.
• Room surfaces can be differentiated using different levels of illuminance to indicate their importance.
• Uniform illumination of the surfaces emphasizes them as an architectural feature.
• Grazing light gives the wall structure by adding patterns of light.
• A decreasing level of brightness across a wall is not as effective as uniform wall lighting at defining room surfaces.
• Lighting effects using gazing light emphasis the surface textures and become the dominant feature.
Examples of defining vertical spatial borders
c- Emphasizing architectural features
• The illumination of architectural details draws attention away from the room as w
whole towards
individual components.
• Columns appear as silhouettes in front on an illuminated wall.
• rooms can be given a visual structure by
illuminating the
architectural features.
• Narrow-beam down lights emphasize the form of the columns.
• Grazing light accentuates individual elements or areas and brings out their form and surface texture.
• Grazing light can cause highly three-dimensional features to cast strong shadows.
• By using different levels or illuminance, different part of a room can be placed in a visual hierarchy
Some example of emphasis of architectural features:
Some types of lighting
4- shading versus lighting
design light for no space exists without shadows.”(1)Shading is an almost essential part of passive building design. there are many different form of solar shading and different uses for it. A part of it is essential to:
a- Reduce the solar heat gain to the room
It is of greatest importance to the south elevations, that are most exposed to the sun. The shading is hence necessary to limit the amount of light coming in the room on one hand, and the amount of solar heat on the other. The shading system used hence has to be controlled manually of automatically, to allow the most of light and heat to come in during cold and cloudy days when light and heat is needed, and limit them during hot sunny days.
b- Reduce glare
Glare usually results from a direct view of the sun, or by reflection from outside sources as well as inside sources (items inside of the building). Glare is annoying and gives a feeling of unease and irritability, hence it has to be controlled by shading the sun or the source of reflection and allowing only light to come into the room (not the sun rays themselves)
c- Allow a level of privacy
Some buildings and especially residential buildings, need a level of privacy for the inside, hence curtains for example are used.
(1) Designing with light and shadow: Kaoru Mende + lighting planners associate Inc.
However, the use of curtains minimizes the income of light from outside and sometimes requires the use of artificial light in days where it shouldnʼt be needed.
So the best solution is the use of some translucent material, which lets through the maximum amount of daylight but breaks the internal image as seen from the outside.
There are many ways to provide this shading, and they are an important part of the design phase, since they are placed on the windows and seen in the elevations. The solar shading systems are now an important industry, high tech and of many aesthetic choices.
In the picture above, we see a movable shading device (such as blinds).
These are only opened when there is a surplus of light and shade is needed.
They donʼt affect the lighting in days with poor daylight.
In the picture below however, we see an example of fixed lightshelf. The first illustration shows the amount of light coming in without the lightshelf, it is too much for the room and causes glare and surplus of light. The second illustration shows the effect of the lightshelf in sunny days: it allows part of the light to come in while reflecting another part into the back of the room. And finally the
In the picture below however, we see an example of fixed lightshelf. The first illustration shows the amount of light coming in without the lightshelf, it is too much for the room and causes glare and surplus of light. The second illustration shows the effect of the lightshelf in sunny days: it allows part of the light to come in while reflecting another part into the back of the room. And finally the