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The Effect of External Shading on Building Heat Gain

Abstract

External shading is an important passive design strategy for controlling solar radiation and reducing unwanted heat gain in buildings. Solar radiation entering through windows and other glazed openings can significantly increase indoor temperatures and cooling requirements, particularly in hot climates. Properly designed external shading devices can intercept solar radiation before it reaches the building envelope, thereby improving thermal comfort and reducing dependence on mechanical cooling systems. This study examines the effect of external shading on building heat gain, focusing on how different shading strategies influence the amount of solar radiation entering and affecting building interiors. Shading elements considered include horizontal overhangs, vertical fins, louvers, balconies, verandas, screens, canopies, and external vegetation. The study also considers factors such as building orientation, window location, shading geometry, seasonal solar angles, and the properties of glazing. The effectiveness of external shading depends largely on its relationship with building orientation and solar exposure. Horizontal shading elements are generally useful for controlling high-angle solar radiation, while vertical elements can provide greater protection from lower-angle radiation on particular orientations. Adjustable or combined shading systems may provide greater flexibility where solar exposure varies throughout the day and across different seasons. The study further considers the relationship between shading and indoor thermal comfort. By reducing direct solar radiation on windows and building surfaces, external shading can limit indoor temperature increases and reduce the cooling load required to maintain comfortable conditions. Shading can also reduce glare and improve visual comfort while allowing controlled daylight penetration into occupied spaces. Despite its benefits, the effectiveness of external shading may be affected by poor sizing, inappropriate orientation, obstruction of daylight, maintenance requirements, construction costs, and aesthetic considerations. Inadequately designed shading devices may provide insufficient solar protection or create undesirable effects on daylight and ventilation. Careful integration of shading with window design, building envelope characteristics, orientation, and local climatic conditions is therefore necessary. The study aims to assess the effect of external shading on building heat gain and identify shading approaches that can effectively improve thermal performance. The findings are expected to assist architects, engineers, developers, and building designers in selecting appropriate shading strategies based on solar exposure and climatic conditions. Ultimately, the study seeks to promote building designs that achieve reduced solar heat gain, improved thermal comfort, lower cooling energy demand, and enhanced environmental performance.

Keywords: External shading, building heat gain, solar radiation, thermal comfort, shading devices, solar control, building envelope, window design, horizontal overhangs, vertical fins, louvers, passive design, cooling energy, climate-responsive architecture.