PASSIVE SOLAR VENTILATION

As the twenty first Century approaches, more emphasis is given to ener gy conservation and passive systems in order to maintain a clean envir onment. New strategies showed the necessity oi.reviewing some design e lements and their evaluation techniques. Architects should seek to inc rease their understanding of the correlation between the natural and t he built environment. In the recent years, many architectural styles s tarted to emerge in Egypt without paying enough attention to their sui tability to the environment and climate. The pitched roof is increasin gly used in both summer resorts and new residential developments and s ettlements in the north west coast of Egypt on the Mediterranean. Thes e locations are characterized by a temperate climate with excessive he at and humidity rates during summer. In general, higher air velocities and numerous air changes per hour can improve comfort conditions in a humid climate. A pitched roof has an advantage of accommodating a pas sive solar chimney collector that induces the natural ventilation depe nding on the thermal difference between indoor and outdoor air tempera tures. Air flow rates increase if the height between inlet and outlet is increased. Meanwhile, when stack height is increased for a roof wit h a fixed area, tilt angle increases and solar heat gain factor facing the same solar altitude decreases. Within the mentioned context, this paper intends to examine the optimum tilt angle for a solar chimney s ystem applied to the study area (32 deg. north latitude) that compromi ses between solar heat gain factor and stack height to insure the best ventilation performance. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.