Knowledge Base DIALux evo

Unit of measure : candela per m² (cd/m²)

Luminance is the basic luminance perceived by the human eye. It is decisive for the impression of brightness of a luminous or illuminated surface.


Luminance L is defined by the luminous intensity Iε of an area A in the direction ε

A * cos ε is the "seen area" from direction ε

If diffuse reflection (Lambert radiators) is assumed for an illuminated surface, a simple relationship between luminance L and illuminance E of this surface results:

ρ = reflectance of the surface

The distribution of luminance between various surfaces in an illuminated interior is an important criterion for the quality of the visual experience. A balanced and harmonious distribution of brightness makes a room pleasant and visually interesting (cf. Brightness, Contrast, Uniformity).