Performance evaluation of a top lighting light-pipe in buildings and estimating energy saving potential

Abstract

Nowadays, an escalation in the development of day-lighting systems is observed as people are fascinated towards day-lighting incorporation so as to get benefitted of the lighting energy savings, along with other intangible benefits like health, well-being, and productivity of the occupants. Light-pipe is one such day-lighting system that enables the natural light to enter the spaces which are located far away from the periphery area of a building and thus, cannot be illuminated by windows or other daylighting devices. Light-pipe, while illuminating the interior spaces, also blocks UV rays, which contributes to the heat gain of a room. The study focuses on the design, optimization, simulation and experimental evaluation of the modification in the conventional light-pipe design towards achieving more light through the pipe. This includes modeling of several structural design modifications in light-pipe and their corresponding ray-tracing simulations in TracePro. Out of these modifications over the conventional straight pipe, the design with the best results has been selected and developed so as to experimentally validate the simulation results. The simulation as well as experimental evaluation of the modified light-pipe in comparison to the conventional light-pipe in terms of the average internal illuminance of the room and the light transmission efficiency of the light-pipe indicates an improvement with the modified design of light-pipe.