Describes a method for numerical simulation of solar radiation entering indoor spaces through fenestration. Proposes a composite grid system, ie an indoor coordinate system used to determine the indoor geometry in which furniture and people exist in a smaller area, and an outdoor coordinate system for investigating the shading effects of other buildings. Both coordinate systems are linked to systematically analyse indoor solar radiation absorption. Areas shaded by surrounding buildings in the outdoor space and areas irradiated in the indoor space are determined by tracing a large number of particles along the direction of the sun emitted at a glass window with the same technique as the Monte Carlo method. Reports the analytical methods of heat gain and heat transfer in a building and demonstrates their application to a model hall.

KEYWORDS: year 1997, Calculating, solar radiation, insolation, solar heat gain, buildings, windows heat flow