Potential Energy Savings with Exterior Shades in Large Offce Buildings and the Impace of Discomfort Glare

Apr 13, 2015

This paper discusses the overall energy use intensity of various external shading systems for a prototypical large office building split into the different types of energy use and for different orientations and window sizes. Lighting energy was calculated for a constant lighting power as well as for dimmed lighting fixtures (daylighting control). In section 3, slat angles and solar cut-off angles were varied for fixed exterior slat shading systems. While the most light-blocking shades performed best for the case without daylighting controls, the optimum cut-off angle with daylighting controls was found to be 30 deg for the used building prototype used in Chicago and Houston. For large window-to-wall (WWR) ratios, window related annual energy use could be reduced by at least 70 % without daylighting control and by a minimum of 86 % with daylighting control in average over all orientations. The occurrence of discomfort glare was is considered in section 4 of the paper, which looks at the performance of commercially available exterior shading systems when an interior shade is used during those hours during which occupants would experience discomfort glare.

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Sabine Hoffmann, Lawrence Berkeley National Laboratory
Eleanor Lee, Lawrence Berkeley National Laboratory
BEST4 Conference proceedings
Presented at: 
BEST4 Conference
Published & professionally reviewed by: 
BEST4 Technical Committee, National Institute of Building Sciences

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