Abstract
The sky luminance is assumed to be uniformly distributed in a method for calculating indoor daylight illuminance using Direct Sunlight Factor, Diffuse Sky Light Factor and Reflected Daylight Factor. Actual sky, however, has a distribution. Therefore the sky luminance distribution has been extensively measured and its mathematical modeling has also been studied by various researchers. Here, in this paper, we first discuss how to incorporate the effects of non-uniform distribution of sky luminance into the method for calculating indoor daylight illuminance using Direct Sunlight Factor. Then we investigate to what extent the non-uniform sky luminance distributions affect the indoor daylight illuminance. As the results of this investigation, the influence of the sky luminance distribution on the indoor daylight illuminance is rather small except a case in which the sky is assumed to be clear and no direct sunlight is assumed to be incident on a window without a shading device.
