An energy-efficient building is a major target of building searchers and designers worldwide. Obviously, any portion of energy that an be saved in this respect can be directed to industrial processes, if any. Building energy consumption can be reduced through various systems such as air conditioning (a major building energy consumer), lighting, equipment, etc. In regions where energy is limited or scarce, air conditioning would have to be replaced by
natural ventilation for the removal the building heat load for thermal comfort. In this article, results of an investigation of atural ventilation criteria as affected by various factors are presented. In particular, the effects of opening location and size (window-to-wall ratio) and building orientation relative to prevailing wind direction are considered. Flow visualization and finite lement techniques were adapted to gain better understanding of these effects. For flow visualization, a smoke tunnel test facility was constructed at the Housing & Building Research Center and utilized to test several idealized building models. On the other hand, a Computational fluid design software (ANSYS FLOTRAN)
was applied to the present problem. Both techniques (visualization and computation) gave clear pictures of what happen inside the ventilated space under different opening locations and ombinations for various wind directions. Knowing the flow structure inside the ventilated space, it would be a simple task to evaluate the thermal comfort index ( ) for a given thermal load (internal heating, solar radiation, etc.). Also, such pictures should help architects to propose good designs of natural ventilation systems in their buildings.