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Prismatic Panel Sidelighting Systems: Daylighting Distribution and Electric Lighting User Patterns in Perimeter Office Workplaces
Glenn SweitzerThe Royal Institute of Technology. Architectural Lighting, Sweden Abstract A pilot study was undertaken to identify the critical effects of prismatic panel sidelighting systems on visual comfort and electric lighting use patterns in perimeter office workplaces. in concept, prismatic panels can be custom-made to optimally reject - according to the sun's movements - direct sunlight and solar heat gain while directing skylight to the interior. In addition, interior window controls and ceiling surfaces can be configured to control luminance distribution. Although several variants of such systems have been installed during the past ten years. neither the claimed benefits nor costs have been either independently confirmed or refuted. The purpose of this pilot study was therefore to study selected installations in situ in order to better compare the outcomes with the original intentions. Three system variants were studied, each in a different bank office building in Germany. Limited observations, discussions with office users, and luminance and illuminance measurements are reported, including a comparison of the latter with results from an earlier study by the system manufacturer. Critical effects of these systems include the distribution of reflections and shadows on ceiling and wall surfaces in addition to horizontal illuminance at the work-plane. In addition, electric lighting is not being switched off or dimmed in response to available daylight. Electricity savings alone, however, cannot - and were not calculated to - payback the system costs for any of the cases studied. More extensive use of prismatic panels will therefore hinge on reduced system costs as well as improved means to extend and account for their daylighting benefits.
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