For indirect lighting systems, ceilings should have sufficient reflectance to efficiently illuminate the room but not have excessive brightness or variation in brightness from luminaires.
Additional Information: For indirect lighting systems, ceilings should be white, should be of matt finish, and should have a minimum surface reflectance of 0.8. In addition, the average luminance on the ceiling, or on other surfaces lit directly, should not exceed 500 cd/m2 (146 ft-L); the peak luminance should not exceed 1,500 cd/m2 (438 ft-L); and the luminance should vary gradually across the surfaces being directly lit.28 11064-6
© ISO. This material is excerpted from ISO 11064-6: 2005 with permission of ANSI on behalf of ISO. All rights reserved.