Numerical and experimental analysis of the ‘Double Light Pipe’, a new system for daylight distribution in interior spaces

An innovative arrangement able to transmit daylight into hypogeal rooms and, simultaneously light the passage spaces, is presented. It is named the ‘Double Light Pipe’. It consists of two coaxial tubes: the inner cylinder is a traditional light pipe, which transmits light from a clear collector, placed on the roof top of the building, downward to a diffuser inside the underground areas, while the outer one allows light to enter into the passage spaces. A numerical analysis has been carried out using ECOTECT and RADIANCE software and the results are compared with a reduced scale experimental analysis.