Using solar screens in school classrooms in hot arid areas: The effect of different aspect ratios on daylighting levels

Hot arid areas are endowed with an abundance of clear skies. Thus, the solar energy available can significantly raise the temperature of interior spaces and also result in an uncomfortable visual environment. External perforated solar screens have been used to control solar penetration through windows. Such screens can also serve a social function, that of maintaining privacy. This paper focuses on a special case of girls’ schools in Saudi Arabia, where the privacy issue is critical due to socio-cultural and religious beliefs. Windows in girls’ schools facing public spaces are typically covered by dark opaque film to maintain privacy. This window treatment results in overreliance on artificial lighting, and in a corresponding increase in energy use. The performance of screens can be affected by many parameters, namely: perforation rate, depth ratio, shape, reflectivity of colour, aspect ratio of openings. This paper looks at how different Aspect ratios affect the performance of screens by simulating a range of cases of different aspect ratios, using the Daylight Dynamic Performance Metrics approach (DDPM). Results recommend using 1:1 aspect ratio for the south orientation whereas using different aspect ratios for the North and West orientations provide better daylight levels in the studied context