An energy-efficient building is a major target in building research and design worldwide. Obviously, any portion of energy saved in this respect can be directed to consumer where energy may be badly needed. Building energy consumption can be reduced through manipulation of various systems such as mechanical air conditioning (a major building energy consumer), lighting, equipment, etc. In regions where energy is limited or scarce, one would have to resort to some natural ventilation system to achieve acceptable thermal comfort for occupants. The form of the building and wind direction determine its natural ventilation performance. This includes building’s shape, number, location, size and form of openings (windows) , the ventilator’s shape, etc. In this paper, results of an investigation of natural ventilation criteria as affected by various factors such as window size WWR (window-to-wall ratio), window location and building orientation (wind direction) are considered. Wind tunnel measurements and finite-element-based computation were adopted to gain an understanding of such effects. A wind tunnel test facility was constructed at the Housing & Building Research Center (HBRC) and utilized to test several idealized building models. On the other hand, a CFD software package (ANSYS FLOTRAN) was applied to the problem. These techniques gave clear pictures of the situation inside the ventilated space with various opening sizes and locations and for several wind directions. With the flow structure inside the ventilated space, it is a simple task to evaluate a thermal comfort index ( ) for a given thermal load (internal heating, solar radiation, … etc.). Results indicate significant effects of WWR, window location and building orientation on such index. Therefore, it is concluded that building designers should not overlook such factors if the buildings is to be naturally ventilated. |
