Comparison of computer and model simulations of a daylit interior with reality

The lighting simulation programme Radiance is used to predict daylight factors and the illuminance distribution in a room which is 12m x 12m x 3.6m high, with grey tinted solar control glazing. These predictions are compared with measurements taken simultaneously in the real room and in a physical model placed outside. Radiance is also used to predict the lighting conditions under a CIE overcast sky distribution. These latter predictions are compared to the predictions obtained by placing the physical model in a mirror box artificial sky. Specific attention is paid to testing the accuracy of results, and the balance between computer calculation time and Radiance rendering settings. Finally the computer model is used to explore the affect of adjusting light shelf finish. The relative contribution of view window beneath the light shelf and clerestory window above is also examined.