Effectiveness of improving indoor uniformity of light shelves using location-awareness technology

Abstract

The light shelf is a natural daylighting system. Recent research has explored integrating IT technologies, particularly location-awareness technologies, into the system. However, most of these studies' design and performance evaluations are limited to focusing primarily on lighting energy savings. This study proposes an enhanced light shelf system that utilizes location-awareness technology to save lighting energy and improve indoor uniformity, and its effectiveness is validated. The proposed system works by modularizing part of the reflector, allowing daylighting performance improvements by concentrating or dispersing daylight according to the average illumination of the zone occupied by people. The performance evaluations were conducted through a testbed, and the main findings are as follows. 1) The proposed system divides the light shelf into modules, improving the performance of previous designs through a control algorithm. 2) This algorithm effectively concentrates or disperses daylight according to the occupant's location, resulting in energy savings and greater indoor uniformity. 3) The proposed system improved the uniformity ratio by 21.1 %–24.0 %, achieving energy savings comparable to previous designs. Thus, using location-awareness technology, this study improves indoor lighting environments and promotes energy efficiency.