Airflow characteristics of modulated louvered windows with reference to the Rowshan of Jeddah, Saudi Arabia
The main aim of this research project is to assess the potential of the modulated louvered windows (ML W) to provide ventilation as a cooling source to achieve thermal comfort inside buildings. It presents an intensive analysis of the characteristics of airflow as function of the various MLW parameters in order to provide designers with practical information about the performance of MLW in the control of natural ventilation inside the room. Some initial studies suggested the significance of adjustable horizontal louvered windows, or the MLW as they are referred to in this research, as an effective technique for the control of natural ventilation beside the other Environmental issues. In Jeddah, Saudi Arabia, the shelter adaptation to the hot-humid climate was achieved by employing a number of passive solutions, one of which, the MLW constructed in the Rowshan, was considered a main elevation treatment. The Rowshan, a projected window bay, covered in this study is constructed with adjustable louvers in a number of sashes arranged in rows and columns to control and alter breeze to the desired level inside the room. The Rowshan is also credited with controlling other environmental factors and is supposed to reflect social necessities. This thesis has investigated the airflow characteristics of the MLW with reference to the Rowshan of Jeddah, Saudi Arabia. After reviewing the previous efforts and prediction techniques concerned, the research has conducted a series of experiments including laboratory and computation fluid dynamics (CFD) appraisal stages. The laboratory stage included the evaluation of the pressure drop (L1J') and the velocity drop (v/ve%) characteristics across the MLW. The pressure drop was examined under various airflow rates (Q) using the depressurising test chamber technique. The velocity drop (v/ve%) was examined under various prevailing wind conditions using the test chamber technique. This appraisal stage covered also the room configuration and its contribution to this effect. On the other hand, the CFD measurement has examined the viability of CFD coding to simulate airflow around the reviewed MLW. The predicted results obtained from CFD were compared against those obtained from the laboratory. Consequently, an intensive evaluation of airflow patterns of the common Rowshan configurations, including the plain and projected Rowshans, employed in leddah in conjunction with various outlet types was conducted. From the literature review, it has been concluded that the MLW played a major role in the provision and the control of natural ventilation in the traditional architecture of leddah, Saudi Arabia. The various appraisal stages showed that parameters such as louver inclination, aperture between louver blades and the free area of the MLW were more significant variables than the depth of louver blades. Nevertheless, the major pressure and velocity drops were not due to individual variable but rather to the combination of variables that would comprehensively describe M and v/ve% across the MLW. Practically, the design of the modulated louvered windows must give consideration to those variables that play an important role in altering airflow characteristics inside the room. It should also have an element of flexibility as this enables designers to approach their window treatments with a number of choices whilst retaining similar ventilation performances. Airflow velocities in a room containing an MLW result from an interaction of louver geometry, room geometry and prevailing wind conditions. As far as the Rowshan configuration was concerned, the plain Rowshan was generally better than the projected Rowshan. Yet the flow in the living zone could be enhanced by correctly sizing the projected Rowshan. Finally, CFD analysis has been successfully used to predict air velocities in the region close to the MLW side.