A new device for distributing concentrated sunlight in building interiors

Abstract In recent years there has been considerable interest in lighting deep within building interiors with guided sunlight. In this paper a new device known as the prism light guide is described and its potential application to daylighting is analyzed. The prism light guide is a hollow acrylic plastic pipe which has optically precise corrugations on the external surface. This shape causes light rays which hit the pipe exterior to reflect back into the pipe, by means of the highly efficient process of total internal reflection. A system has been designed to direct concentrated sunlight into a distribution network based on the prism light guide. An economic analysis of this proposed system is very encouraging. Depending on energy costs and sunlight availability, payback times will range from 3 to 30 years. With mass production of the components, the comparison to all-electric lighting will become even more favourable.