Anidolic daylighting systems

Non-imaging optics, well known for its application to solar concentrators, was used to set up novel daylighting systems that aim at an efficient collection and redistribution of the diffuse component of daylight. These devices, called anidolic systems (an: without, eidolon: image). were designed, installed and monitored on experimental test modules under clear and overcast sky conditions. Three different anidolic systems with different specific objectives were considered (anidolic ceiling, integrated anidolic system, anidolic solar blinds). Installed on 6.55-m deep rooms, the first two showed a significant improvement of daylight factors monitored in overcast conditions in comparison to a reference facade (conventional double glazing): a substantial improvement of the daylighting autonomy can be expected as a consequence. Higher work plan illuminances were observed for the third system under clear sky conditions, demonstrating sunlighting control capabilities that improve visual comfort and overall performance. The present article gives a description of these anidolic systems, as well as an overview of their luminous performance, assessed experimentally within the framework of IEA Task 21. (C) 2002 Elsevier Science Ltd. All rights reserved.