Abstract
This paper deals with the distribution of light incident from sky through lateral window onto interior surfaces of a room with a shape of rectangular prism. As for sky conditions, this paper assumes CIE overcast sky and uniform sky. This paper presents a series of equations for calculating direct illuminance at an arbitrary point on an arbitrary interior surface and luminous flux incident directly on an arbitrary interior surface. In addition, this paper presents a series of graphs that illustrate ratio of luminous flux distributed on an interior surface to total luminous flux incident inside through lateral window.
