Application of external horizontal shading slats for daylighting through north-facing windows

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Simeon Nyambaka Ingabo
Surapong Chirarattananon
Pipat Chaiwiwatworakul


Shading slats allow for illumination of indoor spaces by the use of natural daylight while preventing the penetration of undesirable beam solar radiation. Extensive research has been performed on the use of shading slats on south-facing windows in tropical climate. However, studies on the use of this shading device for north-facing windows are rare, owing to the prevailing assumption that they are not beneficial for north-oriented facades at higher latitudes. This study investigated the operation and energy-saving potential of adjustable external horizontal slats installed on north-facing windows of office buildings in a tropical climate. Full-scale experiments were performed and the results were used to validate a simulation model. Simulations were performed to estimate the energy consumption in offices of varying dimensions over a full year. The appropriate slat adjustment angles for each month were determined and total lighting and air conditioning energy savings of up to 50% were estimated in comparison to the use of unshaded windows with heat-reflective glass.


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