Abstract
About half of the energy loss in buildings is wasted through windows. Determining the optimum window-to-wall ratio (WWR) for different building facades would reduce such energy losses. The optimum WWR is the window area that minimizes the total annual energy of cooling, heating, and lighting. The purpose of this study is to investigate the optimum WWR of different facades of an office building. For this purpose, a sample building is simulated by means of DesignBuilder software in order to investigate the annual solar heat gain, cooling load, heating load, and lighting consumption for the three cities of Bushehr, Shiraz, and Tabriz, and optimum window areas of office buildings for the three cities are determined. Based on the results, the optimum window area for the north building facade for all climates is 20–30%. This amount for the southern facade of the building in Bushehr, Shiraz, and Tabriz is, respectively, 20–30%, 10–30%, and 20–50%. The optimum window area for the eastern and western building facades in Bushehr is 30–50%; in Tabriz it is 40–70%, and in Shiraz it is 20–60% and 40–70%, respectively. The difference between the maximum and minimum energy consumption with different window areas in Bushehr and Shiraz is 20–100% and in Tabriz it is 16–25%.
Highlights
Today, about 50% of the world’s population lives in cities; this proportion is expected to reach 80%by 2030 [1]
The results of this study indicate that increasing the window-to-wall ratio (WWR) between 0% and 90% increases the cooling load and reduces the heating load; in different conditions the total energy consumption of the building has been increased by
Solar heat gain is one of the most important factors associated with the cooling load of a building, which means an increase in the temperature of a space, object, or building that is derived from solar radiation
Summary
About 50% of the world’s population lives in cities; this proportion is expected to reach 80%by 2030 [1]. Large amounts of energy are consumed in the building sector, and cities are responsible for. 70% of global carbon emissions [2,3]. In this situation, it is necessary to consider savings and reduction of energy consumption in all areas, including in buildings [4]. In order to reduce the energy consumption of buildings, the insulation of walls and windows has been increasing. For this purpose, it is necessary to determine the optimum percentage of windows at different facades of the building, especially for the various climate conditions of Iran
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