VARIABILITY OF DAYLIGHT IN LUMINOUS ENVIRONMENTS

This paper reports on the measurements of physical parameters for eval uating the variability of daylight in interior spaces. Luminance and c ontrast are primary variables on visual performance. The spectral vari ation in tile luminous environment affects pupil size, which can affec t visual performance. The variability of daylight affects the :luminan ce and illuminance levels. These variations in illumination levels are measured in a full-scale office space. The photopic and scotopic spec tral content of the ambient illumination on task as well as space surf aces are determined. The results are combined with calculated luminous efficacy of daylight to determine the relative power level for equal pupil size, amplitude, spectral, seasonal and time variation of daylig ht. Variability is also determined. The effective pupil lumen is appli ed as an index to show the variability of daylight in the interior lum inous environment.