Several different window-mounted daylighting devices are now available for supplanting electric sources of illumination.This paper addresses the directional control that these devices exert over their illumination for a room.Two specific devices are examined.One is a light shelf,which is a horizontal reflector.The other device consists of reflectors that are at a compound angle with respect to the plane of a window.The directional performance of these two devices is defined and compared.The results suggest how to specify a combination of the two devices for a room.This study is a preliminary first step for specifying cost-effective combinations of daylighting devices.
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