The Energy Impact of Daylighting PDF

Points out that electric lighting and its associated cooling requirement consume 30% to 50% of the energy used in a typical commercial building. Presents a strategy that reduces the annual costs of illumination by more than 70% without reducing worker productivity. Describes the example of 1620 m² (17,400 ft²) two-storey commercial building, termed the 'Zero Energy Building' designed using load avoidance rather than using alternative sources of energy. The building incorporates a novel daylighting design that utilises beam radiation, thereby avoiding overheating, while simultaneously displacing over 70% of the annual electric lighting load. Novel aspects of the design are 1) a specular light shelf, an exterior reflector and an overhang over the view window, 2) advanced glazings and 3) evaporative cooling. The simple payback period for these measures is 13 years.