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Passive daylighting is a system of both collecting sunlight using static, non-moving, and non-tracking systems (such as windows, sliding glass doors, most skylights, light tubes) and reflecting the collected daylight deeper inside with elements such as light shelves. Passive daylighting systems are different from active daylighting systems in that active systems track and/or follow the sun, and rely on mechanical mechanisms to do so.
Collecting devices rely on their position to most effectively capture sunlight. A building's position as well as architectural considerations are critical in the effectiveness of passive daylighting. Passive daylight systems are typically non-mechanical, and optimal daylighting efficiency is achieved by proper building and system orientation. A southern facing orientation is optimal if a building or system is located in the northern hemisphere, and a northern facing orientation is optimal if located in the southern hemisphere.
Reflecting elements such as light shelves, lighter wall colors, mirrored wall sections, interior walls with upper glass panels, and clear or translucent glassed hinged doors and Sliding glass doors take the captured light and passively reflect it further inside. The light can be from passive vertical windows or overhead skylights-tubes or active daylighting sources. In traditional Japanese architecture the Shōji sliding panel doors, with translucent washi screens, are an original precedent. International style, Modernist and Mid-century modern architecture were earlier innovators of this passive penetration and reflection in industrial, commercial, and residential applications.
The use of all these passive daylighting methods reduces energy consumption from artificial lighting use, creating a more sustainable architecture. They are some of the components in designing for LEED - Leadership in Energy and Environmental Design certification. Specifically, designing for daylighting applies to the IEQ credit "Daylighting and Views", and can contribute to the EA credit "Optimize Energy Performance".