Optimum overhang dimensions for energy saving

A model is presented to predict the effect of window overhangs as passive cooling options on buildings. A computer program is written to calculate hourly cooling load requirements by the numerical solution of the energy balance equation for the building. This simulation is validated by comparison with field data taken from an actual house in Shiraz, Iran. A guideline is presented for optimum overhang dimensions concerning energy saving for buildings situated at latitudes of about 29.6 ° north. Results indicate that for the house under study (of popular size in Shiraz) summer cooling loads may be reduced by 12.7% by appropriate window shading, while only increasing winter heating loads by 0.6%.