×
Menu
Index

Daylight Factor

 
The ratio of the illuminance at a point on a given plane within an interior due to the light received directly and indirectly from a sky of assumed or known luminance distribution, to that on a horizontal plane due to an unobstructed hemisphere of this sky. Direct sunlight is excluded from both values of illuminance (i.e. CIE Overcast Sky).
 
 
 
E = illuminance on unobstructed plane
 
 
 
              e = illuminance at point in interior
 
              Daylight Factor = e/E (often expressed as a percentage)
 
 
              Illuminance is measured in LUX