In this paper the authors present the double light pipe, an innovative technological device, designed as an evolution of a traditional light pipe, which distributes daylight to underground areas of a building. illuminating, at the same time. the passage areas thanks to a larger collector and a second transparent pipe attached to the first one. Unlike the traditional light pipe, thanks to this double illuminating function it can be located in the middle of a room, despite its encumbrance. In this paper the technological design of the double light pipe is presented and the results of an experimental analysis on a reduced scale (1:2) model are shown. Internal illuminance data over horizontal and vertical work-planes were measured in various sky conditions with or without direct solar radiation. Being this innovative device obtained by a light pipe integrated with a second pipe, it performs like a traditional light pipe for the final room and, at the same time. illuminates the intermediate room giving it uniform and high quality light, particularly indicated for wide plant areas, such as show-rooms Museums. (C) 2009 Elsevier Ltd. All rights reserved.