Daylight performance of horizontal light pipe with egg-crate reflector in the tropics

Abstract

Horizontal Light Pipe (HLP) is one of a light transport system that can guide daylight deeper into building interiors. Improvement of HLP's light distribution by installing an egg-crate reflector at its opening distribution was conducted. The study's aim was to evaluate and explain the daylight performance of HLP with an egg-crate reflector at office space in the tropics. Experiment with physical scaled model 1:5 was used as a research method. Illuminance value, Daylight Factor (DF), uniformity ratio and diversity of illuminance of an office space lit by side window (base case) were compared to the office space lit by side window and HLP with an egg-crate reflector (case), simultaneously with daylighting standards. The results showed that HLP with egg-crate reflector improved daylight level and distribution. Improvement of DF and illuminance level were in the range of 16.6 % to 56.6 %. The uniformity ratio of the base case was in the range of 0.35 to 0.45, while in the case was in the range of 0.48 to 0.66. The diversity of illuminance of the base case at a low altitude of the sun (15:00) exceeded 5:1 while in the case was kept lower than 5:1 at all the measurement time.