Lightpipe applications for daylighting systems

One of the main research activities of the Institute of Lighting at Technical University of Berlin concerns efficient daylight utilisation in buildings. In recent years, several national and international projects have been and are still carried out. One of them, the European research project ARTHELIO, has examined the possibility of guiding daylight into deeper building interiors using hollow light guides. The aim is to provide daylighting in deeper building interiors. Within this project, a goniophotometer was developed and built, to measure the luminous intensity distribution of lightpipes. In two demonstration sites, the daylight utilisation by the hollow light guides combined with heliostats has successfully been demonstrated. Daylight is collected by heliostats and enters the building. It is guided along hollow light guides and coupled out along its way to illuminate the building interior. Measurements show that the prototypes help to decrease the energy consumption for electric lighting of the building. 2004 Elsevier Ltd. All rights reserved.