Luminaire arrangement

Recommendations on optimal luminaire arrangement

Designing the lighting layout should not be seen as a solely technical or functional process. In quantitative lighting design, it has become preferred practice to plan the lighting layout of ceiling-mounted luminaires to produce a completely uniform grid, with the aim of providing uniformly distributed lighting.
Consequently, there is no direct link between lighting layout and lighting effect; by exploiting the wide range of luminaires available it is possible to achieve a designed pattern of lighting effects using a variety of lighting layouts. The lighting design should make use of this scope, producing ceiling designs that combine functional lighting with an aesthetic lighting layout that relates to the architecture.



The recommended offset from the wall (a) is half the luminaire spacing (d). The luminaire spacing (d) between two adjacent structures should correspond to the height (h) above the floor or work surface.

No light is emitted beyond the cut-off angle.

30° cut-off angle

40° cut-off angle

50° cut-off angle

Cut-off angle

The greater the cut-off angle, the greater the visual comfort provided by the luminaire due to improved glare control. The same lighting layout of downlights produces different distributions on the wall.
A cut-off angle of 40° gives the best possible compromise between the necessary horizontal illuminance on the floor and vertical illuminance.
Vertical illuminance is important in places such as salesrooms where products should be well illuminated. On downlights with a 30° cut-off angle, the maximum luminous flux is emitted at a high lateral angle.
Due to their narrow light distribution, downlights with a 50° cut-off angle achieve very a high visual comfort for high rooms.



The distance from the wall for wallwashers should be at least one third of the room height. Alternatively, the wall offset is given by a 20 degree line extending from the base of the wall up to the ceiling. Whereas for normal room heights the luminaire spacing is the same as the wall offset, in high rooms this spacing must be reduced to compensate for the illuminance which is generally reduced. Wallwashers do not give optimum uniformity until at least three luminaires are used. A wallwasher in a room corner should be positioned on the 45° line.

Room corner

The recommended distance of downlights to the wall is generally half the distance between the downlights. Corner-mounted luminaires should be mounted on the 45° line to produce identical scallops on both walls.

Mirrored walls

For mirrored walls, the lighting layout should be chosen such that the pattern continues uniformly in the reflection.

Wall element

In spaces with dominant architectural features, the lighting layout should harmonise with the architectural elements.


Ceiling lighting requires sufficient room height to achieve even light distribution. Ceiling washlights should be mounted above eye-level to avoid direct glare. The ceiling offset depends on the degree of evenness required and should generally be 0.8m.



Objects can be illuminated with light directed from between 30° to 45° to the vertical. The steeper the incident light, the more pronounced the three-dimensionality of the illuminated object. If the angle of incidence of the light is approximately 30°, the so-called "museum angle", this produces maximum vertical lighting and avoids reflected glare that may disturb the observer. In the case of reflecting surfaces, e.g. oil paintings or pictures framed behind glass, attention must be paid to the angle of incidence of the light to avoid disturbing reflections that may arise in the observer's field of vision. This will also avoid any heavy shadow, e.g. picture frame shadows on the picture.

Horizontal surfaces

High luminance values reflected by surfaces or objects cause secondary glare. The luminaires should not be positioned in critical areas. Indirect illumination with diffuse light reduces the secondary glare. The beam should be aimed such that shadows on the work surface are avoided.

Vertical surfaces

If a reflective surface is arranged transversely, luminaires can be mounted in front of the excluded ceiling zone. If a reflective surface is arranged vertically, they can be mounted next to the excluded ceiling zone.

Point source patterns

Point sources: regular and staggered layouts

Point source

The simplest layout of these points is a regular grid, in a parallel or staggered arrangement. A regular pattern of identical luminaires can easily result in a monotonous ceiling appearance, plus the fact that differentiated lighting is practically out of the question.

The point sources may be luminaires of different shapes and sizes, or compact groups of luminaires.

Point source combinations

An alternating grid of different individual luminaires or luminaire combinations can produce more interesting arrangements; in this case luminaires of the same or different types can then be purposefully combined. The use of different luminaire types, by alternating positioning or through combinations, allows the lighting qualities of a visual environment to be carefully controlled.

Point sources:
Linear arrangements


A further step towards more complex design forms is the linear arrangement of point sources. In contrast to simple lighting layouts in grid patterns, the ceiling design in this case relates more closely to the architecture of the space. The ceiling is designed along the lines dictated by the architectural form of the space. This may involve following existing lines or purposefully arranging the luminaires in contrast to the existing formal language.

Luminaire arrangements can follow existing architectural structures or create patterns of their own.


Since the linear arrangement of the luminaires does not necessarily relate to an actual line such as the course of a wall, ceiling projections or joists, the luminaire arrangement can only be created on the basis of the perception of gestalt. These laws of gestalt must receive special attention during the planning phase. The crucial criteria are the equidistance and proximity of luminaires to each other.

Linear elements


Whereas linear arrangements consisting of a series of points are only produced indirectly by our perception of the gestalt, they can also be directly formed of linear elements. These linear elements can be particular types of lumiaires, or even trunking systems. Light structures and track arrangements or other trunking systems belong to this design category.
The formal language of linear arrangements is identical to that of rows of points. As the visual forms produced when linear luminaires are used are real and not just implied, more complex arrangements can be planned with no danger of distortion through perception.

Linear and point sources

Creative design allows both the alternating application of different luminaire forms and the use of spotlights on lighting structures or trunking systems. This allows differentiated lighting without the individual luminaires disturbing the intrinsic appearance of the structure.

Decorative solutions

The combination of different elements gives rise to a broad range of design possibilities, including decorative solutions.

Linear structures

The rectangular arrangement of tracks corresponds to the shape of the room. This allows flexible lighting of all wall surfaces and accentuating of objects in the space.

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