Studying the Principles of Window Design for Energy-Efficient Buildings in the Gaza Strip

Abstract

Windows are one of the most necessary envelope elements in any building, as they provide access to views, daylight, and also function as part of the ventilation system. However, they are the weakest thermal link in a building envelope for heat gain in summer and heat loss in winter. Thus, window design has a significant impact on building energy consumption. In general, windows affect a building’s thermal state by transmitting solar radiation directly into indoor spaces. This gain is beneficial in winter and undesirable in summer as it can overheat the space. Therefore, the critical design issue is to control this solar gain in relation to the summer and winter requirements. There are four factors that control the solar gain entering through windows which are: size, orientation, glass material and shading device of windows. This research aims to examine these factors in accordance with local environmental conditions of the Gaza Strip. In order to achieve the purpose of research, an parametrical study is carried out by "IES VE" and "ECOTECT" programs to assess the effect of window on energy consumption of a typical residential building in the Gaza Strip. The study concluded that the appropriate window design in the Gaza Strip buildings can effectively reduce the energy consumption. It found that the optimal windows orientation is by elongating the long axis of the building along east-west direction. It also concluded that the minimum percentage of windows by (10%) of the total facade area is the optimum size for all facades. The direct impact of south window is considered the worst, as it causes the largest energy consumption. In addition, the study emphasized that using advanced glazing materials with low U-value is an important factor in reducing the energy demand. It also confirmed that the horizontal device with relatively short depth is the appropriate type for south window, whereas the compound (horizontal and vertical) device with long depth is the most effective for west and east windows.