Somnium represents also the perceptive balance in terms of
contrast between the optical structure and background. The
luminance contrast, defined by the relation between the object
and background luminances, is an important parameter in
light design. Somnium respects values of luminous contrast
up to 100, normally considered comfortable applications, in
accordance with standards and other recognized parameters*.
C = (Lobj - Lbg) / Lbg
where:
Lobj = object luminance
Lbg = background luminance
Object luminance around us is generally between 10-20 cd/m2 (not directly
illuminated object) and 1500 cd/m2 (directly illuminated ceiling from indirect light
source).
*EN 12464 requires < 3000 cd/m2
WELL requires < 6000 cd/m2
Perceptive
light principle
Balanced luminance and contrast
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