Preferred luminance distribution in windowless spaces

The relationship of preferred ceiling luminance to that of recessed louvered fittings at different luminance levels was determined by observations in a model representing a windowless office. By optical simulation, observations were also made to determine optimum luminance of surface-mounted fittings in relation to illuminance. Preferred luminance levels gave a degree of glare approaching IES recommended limits at 500 lux, but a lower degree was required at higher levels. Preferred ceiling luminances with the surface-mounted fittings were in the region of 150-200 cd/m 2 .