Using light to optimally emphasise the nocturnal effect of buildings

The form of facades is determined not only by their material and shape but also by the light and its direction and colour. The appearance of a facade alters during the course of the day due to the changing direction of light and the varying components of diffuse and direct light. Different light distributions and the use of lighting control systems give facades an appearance of their own at night. Varying illuminances differentiate components or areas of a facade. Grazing light emphasises facade details. Washlighting facades allows them to appear in their entirety. Shining any light beyond the facade surfaces, either to the sides or over the top, should be avoided.

Solid facade

Washlighting creates a very uniform light distribution on the facade. A line of light marks out the edge of the building against the night sky. Uplights rhythmically divide up the facade. Under the light of up-downlights, graphic patterns are produced by the definite beams.
Washlighting facades can make them appear flat. Reducing the illuminance as the facade height increases gives a low-contrast transition to the dark night sky. Grazing light emphasises the surface textures of materials. Progressions of light on untextured walls become the dominating feature and are seen as independent patterns in their own right. Large, uniform surfaces can be given structure with patterns of light. Beams of light that do not match or correspond with the architecture are perceived as disturbing.

The facade lighting can be positioned on the ground, on a mast or on the building. Wallwashers offset from the facade at one third to half the facade height avoid long shadows. Luminaires positioned close to the facade produce grazing light with a strong emphasis on the surface textures and structures. Recessed floor luminaires are architecturally discrete. Overgrown vegetation must be prevented. Mast luminaires will appear as additive features in front of the facade. Cantilever arms allow direct mounting to the building. Shining any light beyond the facade surfaces, either to the sides or over the top, should be avoided.

Solid facade

Vertically divided facade

Floodlights produce a uniform illumination on the facade. Washlighting with point-shaped light sources makes the surface texture and structure clearly visible. Accentuating the columns detaches these from the surrounding facade. Uplights positioned on two sides emphasise the volume of the column. Downlights accentuate the column and illuminate the floor area. The combination of uplights and downlights augments the vertical facade division by lighting from above and below.
Narrow beams of light intensify the effect of the vertical division. To avoid shadows at the side, the luminaires should be positioned at right angles, parallel to the facade. Strong contrasts and heavy shadow can be compensated for by washlighting the facade as a form of general lighting. The luminaires should be positioned in a rhythm corresponding to that of the facade divisions.

Vertically divided facade

Vertically divided facade

Horizontally divided facade

Floodlights illuminate the entire facade and emphasise the horizontal divisions by casting heavy shadows. Lines of light echo the horizontal structure on the darker facade surface.
Luminaires positioned close to the facade highly emphasise its three-dimensional nature. Long heavy shadows cast by facade divisions can be reduced by increasing the offset of the luminaire from the facade. The steeper angle of incidence for the light in the upper region of the facade casts longer shadows than in the lower area.

Facade with projecting or recessed sections

Wide-beam floodlights set far from the building illuminate the facade evenly. Facades with large protruding sections or insets will feature heavy shadows. Different illuminances or light colours augment the differentiation of the facade. Uplights mark out the internal corners with grazing light.
Differentiated illuminances, light distributions and light colours add rhythm to the appearance of the facade. Harsh contrasts between accentuated and unlit areas can be compensated for by using washlighting to perform the general lighting. Increasing the luminaire offset from the facade reduces the formation of heavy shadow. The luminaire arrangement should correspond to the pattern of facade division.

Perforated facade

Under daylight conditions the window surfaces appear dark. At night, illuminated interiors provide a strong contrast between the dark facade surface and bright windows. Floodlights produce uniform light distribution over the facade. Illuminating the window embrasure accentuates the frame of the facade opening, whereas narrow-beam uplights emphasise the facade‘s grid pattern.
Indoor users should not be dazzled. Luminaires shining into the interior impair the view out of the building. Lighting control systems can be used to control the light in individual rooms and to create patches of light on the facade.

Banded facade

Under daylight conditions the strip of windows appears dark. Illuminating the indoor areas at night forms a strong contrast between dark facade surfaces and a bright strip of windows. The lighting on the balustrades augments their horizontal structure.
The strong contrast between bright indoor lighting and the dark outer surface at night can only be compensated for to a small extent with facade washlighting.

Transparent facade

Under daylight conditions, the transparent facade appears dark and reflects its surroundings. Indoor lighting allows the observer to see into the building. Ceiling washlights in the indoor area emphasise the ceiling surfaces and increase the overall impression of interior brightness at night. The facade construction is silhouetted. Lines of light in the ceiling area of the individual floors underline the horizontal building structure. Uplights emphasise the vertical elements of the facade.
The visual perspective from the ground makes the lighting effect of the indoor area appear larger with uplights than with downlights. Dazzling the users of the indoor area should be avoided. Luminaires shining into the interior will impair the view out of the building.

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