Simulation and experimental studies on natural lighting in enclosed lift lobbies of highrise residential buildings by remote source solar lighting

The residential buildings in Hong Kong are often developed into highrise central core blocks due to limited buildable land and dense population. The lift lobbies in these buildings are enclosed without windows and their floor heights are restricted to not more than 2.8 m. Electric lighting is switched on continuously for 24 h a day. This paper investigated an alternative way to provide lighting for the enclosed space by solar energy via a remote source solar lighting system. The detailed analysis on different layouts of typical lift lobbies are reported first and then the remote source solar lighting system is proposed, which is composed of a simple heliostat and side-emitting fiber optic. Simulation on the light transmission performance in the system was carried out by the ZEMAX-EE. An experiment was carried out to validate the simulation results. The validated simulation results can reveal the performance of the side-emitting fiber optic lighting system. The results show that the proposed remote source solar lighting system can be applied as an alternative lighting system to illuminate the enclosed lift lobby at daytime in clear sky condition.