Three computer programs have been developed for use in assessing solar heat gain through windows in buildings. SUNSPEC calculates the direct beam and diffuse sky solar spectral and broadband irradiances incident on an arbitrarily oriented plane, for any position of the sun in the sky relative to the receiving plane. The calculations are for a cloudless sky and allow the user to specify the concentrations of various atmospheric gases and particulates. AWNSHADE calculates the unshaded fraction of a vertical window's area when illuminated by direct bearn solar radiation. It also calculates an approximate effective unshade fraction for a window illuminated by isotropic radiation from the sky and from the ground. Shading geometries allowed by AWNSHADE include awnings with horizontal or inclined sidewalls, overhangs, and vertical sidefins with horizontal or inclined top edges, and combinations of these. SUNPATH calculates the position of the sun in the sky for any day of the year, time of day, and location on earth, as well as sequences of positions, called sunpaths, on one or more selected days in the year. It also plots sunpath diagrams on the screen and to print files.