The design and assessment of advanced daylighting systems integrated with typical interior layouts in multi-story office buildings

Two sidelighting solutions—a light shelf system and an optical louver system (FISCH)—are assessed and compared in terms of lighting quantity and quality in multi-story office buildings. The systems are integrated with various interior layouts typical of modern office environments, and developed in the context of an optimized structural system to achieve high ceilings. Experiments are conducted in six phases addressing the following issues: (1) Light Shelf Top Surfaces; (2) Partition Materials; (3) Placement of Partitions parallel to window wall; (4) Placement of Partitions perpendicular to window wall; (5) Ceiling Height; (6) Comparisons of the Light Shelf & the FISCH system. Lighting quantity is evaluated by using Coefficient of Utilization (CU) as an indicator, and lighting quality is evaluated by examining the luminance ratios on major interior surfaces and by studying the size and duration of direct sunbeams admitted through the daylight glazing and view glazing. The study results indicate that: (1) Specular and semi-specular reflectors on the top of light shelve give better light quantity deep in the building than do glossy white or flat white surfaces. Compared to specular reflectors, semi-specular reflectors tend to give better luminance distributions; (2) Compared to opaque partitions, translucent partitions give superior illuminance levels deep inside the building and they also produce superior light quality in the form of less extreme luminance ratios in the space; (3) In the partitions, it is highly desirable to use fairly high transmittance glazing and to use clear glazing (rather than translucent glazing) above the level required for visual privacy (e.g., from the top of the door up to the ceiling). It is also desirable to minimize the number and width of mullion elements, to allow as much light as possible through the partition.; The effect of ceiling height is also examined for the various daylighting system configurations and the optimal daylighting systems configurations are identified for each ceiling height. One of the most promising daylighting configurations was selected to integrate with an electric lighting system. The potential electric lighting reductions are predicted on a full-year basis in the context of Raleigh, North Carolina.