Sustainable Building Technical Manual - Etn-presco.net

LIGHT SHELFFigure 5❑ Consider solar shade and awning systems.These systems often project out from the building surface above the window or are in thesame plane as the window glazing (usually in the upper portion of the window). They areengineered to collect light from a variety of angles and redirect it by specular reflectiontoward the deepest portion of the room and generally upward toward the ceiling plane.❑ Consider optical venetian-blind systems.These systems work like standard venetian blinds except that they have diffraction gratingsor micro-fresnel lens surfaces and some have individual slats that are shaped like collapsedprisms. Like their standard miniblind counterparts, they can be operated manually with awand-type actuator or automatically with new photosensor light-angle measuring systemsand computer software control algorithms.❑ Consider advanced light-shelf systems.These systems utilize many of the same advanced glazing technologies as solar shading systems;however, they are arranged in projecting configurations that look and act like standardlight shelves but offer much better control of light direction and higher efficiencies. Whiletypical light shelves may be expected to maintain relatively even daylight illumination for adepth of up to 2.5 times the distance to the top of the window into the room, advanced lightshelves (Figure 6 and Figure 7) should maintain even illumination up to four times the distancefrom the floor to the top of the glass opening under certain conditions. 10 Tracking systemshave an advantage over passive systems in that they maintain more uniformefficiencies and resulting light-distribution patterns but have greater potential for problemsand associated maintenance costs.I n n ovat i ve Toplighting SystemsThe primary challenges to toplighting applications are the need for collimation of light verticallydeeper into the interiors of high-rise buildings and the need for higher efficiency and betterdistribution control allowing greater distance between skylights in single-story applications.❑ Consider advanced systems such as active concentrating heliostats, passive collimatingsystems, and high-performance optical skylights. 11Technologies that may be applied in these strategies are similar to those mentionedabove for innovative sidelighting systems.