Dobashi, YoshinoriKaneda, KazufumiNakashima, TakanobuYamashita, HideoNishita, Tomoyuki and Tadamura, Kastumi2014-10-212014-10-2119941467-8659https://doi.org/10.1111/1467-8659.1330085It is inevitable for indoor lighting design to render a room lit by natural light, especially for an atelier or an indoor pool where there are many windows. This paper proposes a method for calculating the illuminance due to natural light, i.e. direct sunlight and skylight, passing through transparent planes such as window glass. The proposed method makes it possible to efficiently calculate such illuminance accurately, because it takes into account both non-uniform luminous intensity distribution of skylight and the distribution of transparency of glass according to incident angles of light. Several examples including the lighting design in an indoor pool, are shown to demonstrate the usefulness of the proposed method.10.1111/1467-8659.133008585-96