Daylight performance assessment and design strategies in the adjoining spaces of atrium buildings

Daylight use in an atrium is particularly beneficial as the natural light can illuminate potentially dark core areas and decrease energy consumption. This study has investigated, for overcast sky conditions, the vertical daylight levels on atrium well walls and the horizontal daylight levels in adjoining spaces in atria. The daylight levels in the rooms and on the walls were derived from scale model measurements, theoretical calculations and predictions from the lighting simulation package Radiance. A comparison of the three data sets showed generally good agreement. Some limitations in the calculations used in determining the daylight factors in rooms with large window area to total wall area ratios were observed. In terms of the well geometry and well façades (decided by the ratio of window area to solid wall area) and well surface reflectance, the variations of daylight level in the adjoining rooms have been analysed and some design strategies for supporting preliminary design decisions are presented.