Maintains that design information on window shading coefficient or solar heat gain coefficient, such as that contained in the ASHRAE Handbook of Fundamentals (ASHRAE 1989), is inadequate for the passive solar designer. The tabulated data on shading coefficient does not cover the new high-performance glazing systems, is tabulated for the summer condition only and ignores any frame or edge-of-glass effects. Expands the table of centre glazing solar heat gain coefficients (SHGCs), examine the effect of solar radiation, wind speed and ambient temperature and quantifies frame and edge SHGC. States the result is a simple procedure to calculate total window SHGC.

KEYWORDS: Windows, solar heat gain, shades, designing, passive, solar heating, calculating