Guide - Basics - Perception-orientated lighting design

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Perception-orientated lighting design

Perception as the starting point of good lighting design

The perception-orientated lighting design of the 1960s no longer considered man and his needs as a mere recipient of his visual surroundings but as an active factor in the perception process. The designers analysed what was the significance of the individual areas and functions. Using the pattern of meaning thus established, it was then possible to plan the lighting as a third factor and to develop an appropriate lighting design. This required qualitative criteria and a corresponding vocabulary, which in turn allowed both the requirements placed on a lighting system and the functions of the light to be described.

Richard Kelly

Richard Kelly (1910-1977) was a pioneer of qualitative lighting design who borrowed existing ideas from perception psychology and theatrical lighting and combined them into a uniform concept. Kelly broke away from the rigid constraints of using uniform illuminance as the central criterium of the lighting design. He replaced the question of lighting quantity with the question of individual qualities of light. These were designed according to a series of lighting functions, which were in turn geared towards the perceiving observer. In the 1950s Kelly made a distinction here between three basic functions: ambient luminescence, focal glow and play of brilliants.

Ambient luminescence

Kelly called the first and foundational form of light "ambient luminescence". This is the element of light that provides general illumination of the surroundings; it ensures that the surrounding space, its objects and the people there are visible. This form of lighting facilitates general orientation and activity. Its universal and uniform orientation means that it largely follows along the same lines as quantitative lighting design, except that ambient luminescence is not the final objective but just the foundation for a more comprehensive lighting design. The aim is not to produce blanket illumination, or "one size fits all" lighting at the supposed optimum illuminance level, but to have differentiated lighting that builds on the base layer of the ambient light.

Focal glow

To arrive at a differentiation, Kelly came up with a second form of light, which he referred to as "focal glow". This is where light is first given the express task of actively helping to convey information. The fact that brightly lit areas automatically draw our attention now comes into consideration. By using a suitable brightness distribution it is possible to order the wealth of information contained in an environment. Areas containing essential information can be emphasised by accented lighting, whereas secondary or distracting information can be toned down by applying a lower lighting level. This facilitates a fast and accurate flow of information, whereby the visual environment is easily recognised in terms of its structures and the significance of the objects it contains. This applies just as equally to orientation within the space (e.g. the ability to distinguish quickly between a main entrance and a side door) as for emphasising certain objects, such as when presenting goods for sale or when highlighting the most valuable sculpture in a collection.

Play of brilliants

The third form of light, "play of brilliants", results from the insight that light not only draws our attention to information, but can also represent information in and of itself. This applies above all to the specular effects that point light sources can produce on reflective or refractive materials. Furthermore, the light source itself can also be considered to be brilliant. This "play of brilliants" can add life and ambiance, especially to prestigious venues. What was traditionally produced by chandeliers and candlelight can now be achieved in a modern lighting design by the targeted use of light sculptures or by creating brilliant effects on illuminated materials.

Glass House

Architect: Philip Johnson
Location: New Canaan, Connecticut, 1948-1949

It was on this Glass House project that Kelly developed the basic principles of indoor and outdoor lighting which he was to later apply to countless residential and business properties. Kelly avoided the use of blinds for the sunlight because he found they obscured the view and impaired the feeling of distant space. Instead, to reduce the harsh daytime brightness contrast between inside and outside, Kelly used dimmed lighting on the interior walls. For the night, he designed a concept that works with the reflection of the glass facade and retains the spatial feeling. Kelly recommended candles for the interior as this would give sparkle and add an exciting atmosphere. Several lighting components in the outdoor area augment the view out of the living area and create spatial depth. Projectors on the roof illuminate the front lawn and the trees beside the house. Additional projectors highlight the trees in the middle ground and the background, thereby making the landscape backdrop visible.

Photos courtesy of the Kelly Collection.

Seagram Building

Architects: Ludwig Mies van der Rohe and Philip Johnson
Location: New York, New York, 1957

The vision behind the Seagram Building was to have a tower of light that would be recognisable from afar. Working together with Mies van der Rohe and Philip Johnson, Kelly achieved this aim by having the building shine from the inside out. This was done using luminous ceilings in the office levels, whereby a two-stage light switch for the fluorescent lamps enabled energy to be saved at night. The illumined area at the plinth of the building gave the impression that this multi-storey building is floating above the street. An impressive view into the building at night is afforded thanks to uniform vertical illumination of the building’s core, produced by recessed ceiling luminaires. A carpet of light starts in the indoor area and continues onto the forecourt. To achieve a uniform pattern of solar protection on the facade during the daytime, the blinds on the windows only have three settings: open, closed and half-open.

New York State Theater

Lincoln Center for the Performing Arts
Architect: Philip Johnson
Location: New York, New York, 1965

For the New York State Theater Kelly explored the use of crystalline structures for the design of the chandelier in the auditorium and the lighting of the balcony balustrades in the foyer. The chandelier in the auditorium had a diameter of about three meters and consisted of a number of smaller "diamonds of light". In the foyer, the luminaires on the balustrade were designed to look like jewels in a crown, thereby underlining the grandeur of the room. The light sources were shielded towards the front side of the balustrades, but on the inside their multi-facetted structure produced impressive reflections. This results in brilliance effects comparable with the sparkle of precious stones. In addition, Kelly also conceived the lighting in all the other areas of the Lincoln Center, except the interior of the Metropolitan Opera House.

Kimbell Art Museum

Architect: Louis I. Kahn
Location: Fort Worth, Texas, 1972

The clever use of natural light in the Kimbell Art Museum originates from the teamwork of Louis Kahn and Richard Kelly. Kahn designed a series of North-South orientated galleries whose vaulted ceilings featured a skylight running along their apexes, while Kelly was responsible for the daylight reflector system made of curved aluminium plate. Perforations allow daylight to penetrate through this plate, thereby reducing the contrast between the underside of this reflector and the daylight-illuminated concrete vaulting. The central section of this dished aluminium is kept free of perforations so that direct daylight is shut out. In areas with no UV protection requirements, such as the entrance or the restaurant, a completely perforated reflector is used. Computer programs were used to calculate the reflector contour and the lighting properties that were to be expected. The underside of the daylight reflector system was fitted with tracks and spotlights. Kelly suggested putting plants in the inner courtyards in order to tone down the harsh daylight for the indoor areas.

Yale Center For British Art

Architect: Louis I. Kahn
Location: New Haven, Connecticut, 1969-1974

Louis Kahn teamed up with Kelly to design a system of skylights for the illumination in the Yale Center for British Art. The design brief from the museum was that on sunny and overcast days the pictures were to be exclusively illuminated by daylight. Artificial lighting was only to be mixed in when there was very low daylight. The domed skylights feature a permanently mounted louvre construction on the topside, allowing diffuse northern light into the building while avoiding directly incident light on walls or floors when the sun is high. The skylights are made of an upper Plexiglas dome with UV-protection and a sandwich construction consisting of: a translucent plastic plate for dust protection, a mirror-finish light diffuser and a bi-laminar, acrylic, prismatic lens underneath. Tracks on the undersides of the domed skylights hold wallwashers and spotlights. The design process utilised computer calculations and full-scale models.

William Lam

In the 1970s, William M. C. Lam (1924-2012), one of the most committed advocates of qualitatively orientated lighting design, produced a list of criteria, or rather a systematic, context-orientated vocabulary for describing the requirements placed on a lighting system. Lam distinguished between two main groups of criteria: the "activity needs", which are the needs resulting from performing activities within a visual environment, and the "biological needs", which sum up the psychological demands placed on a visual environment and are applicable in every context.

Activity needs

The "activity needs" describe the needs resulting from performing activities within a visual environment. The characteristics of the visual task at hand are the crucial factor for these needs. The analysis of the activity needs is therefore largely identical with the criteria for quantitative lighting. There is also considerable agreement for this area when it comes to the objectives of lighting design. The aim is to arrive at a functional lighting that will provide the optimum visual conditions for the activity in question - be it work, leisure activities or simply moving through the space. In contrast to the proponents of quantitative lighting design, Lam objects to a uniform lighting that is simply designed to suit whatever is the most difficult visual task. Instead, he proposes a differentiated analysis of all the visual tasks that arise, an analysis conducted according to location, type and frequency.

Biological needs

Lam sees the second complex of his system, i.e. the "biological needs", as being more essential. The biological needs sum up the psychological demands that are placed on a visual environment and are applicable in every context. Whereas activity needs result from a conscious involvement with the surroundings and are aimed at the functionality of a visual environment, biological needs largely concern unconscious requirements which are fundamental for evaluating a situation emotionally. They are concerned with the feeling of wellbeing in a visual environment. The starting point for Lam’s definition is the fact that our attention is only dedicated to one specific visual task in moments of utmost concentration. Our visual attention almost always widens to observe our entire surroundings. This allows changes in the environment to be perceived immediately and behaviour to be adapted to the altered situation without delay. The emotional evaluation of a visual environment depends not least on whether that environment clearly presents the required information or whether it conceals it from the observer.


Of all the fundamental psychological demands placed on a visual environment, Lam ranks the need for clear orientation as paramount. Orientation can be initially understood in spatial terms here. In which case, it would then relate to how discernable destinations and routes are and to the spatial location of entrances, exits and other specific facilities within the environment, e.g. a reception desk or the individual areas of a department store. But orientation also concerns information on further aspects of the surroundings, such as the time of day, the weather or what is going on in that area. If this information is missing, as may be the case in closed spaces in department stores or in the corridors of large buildings, then the environment is perceived as unnatural and even oppressive. It is only by leaving the building that we can catch up with the information deficit.


A second group of psychological needs concerns how well the surrounding structures can be discerned and comprehended. The first point to note here is that all areas of the spaces are sufficiently visible. This is the decisive factor for our feeling of security within a visual environment. Dark corners in subways or in the corridors of large buildings may harbour danger, in the same way as glaringly overlit areas. Comprehension of our surroundings does not simply mean that absolutely everything has to be visible however, it also includes an element of structuring, i.e. the need for a clearly structured and ordered environment. We perceive situations as positive not only when the form and structure of the surrounding architecture are clearly discernable, but also when the essential areas are clearly delineated from their background. Instead of constituting a confusing and possibly contradictory deluge of information, a space presented in this way will feature a comprehensible number of properties that build into a clearly structured whole. Having a nice view or other points of visual interest, such as a work of art, are also important for relaxation.


A third area covers the balance between man’s need for communication and his requirement for a defined private sphere. Both extremes here are perceived as negative, i.e. complete isolation as well as "life in a goldfish bowl". A given space should facilitate contact with other people, yet at the same time it should also allow private areas to be defined. One such private area could be defined by a patch of light that picks out a group of seats or a conference table from the overall surroundings within a larger room.

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