Performance evaluation of a light shelf with a folding reflector (LSFR) to improve daylighting performance

• Published in: Building and environment Vol. 255; p. 111457
• Main Authors: Zhao, Xiaolong, Seo, Janghoo, Lee, Heangwoo
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-05-2024
• Subjects: Energy saving; Folding; Light shelf; Performance evaluation; Performance evaluation; Light shelf; Energy saving; Folding
• ISSN: 0360-1323
• DOI: 10.1016/j.buildenv.2024.111457

Recently, light shelves have been in the spotlight as a solution to the increasing lighting energy consumption in buildings, and various studies have confirmed their effectiveness. However, there is a lack of research on light shelves that operate according to the solar azimuth. To address this, this study proposes a light shelf with a folding reflector (LSFR) that operates in alignment according to the solar azimuth and validates its effectiveness through a testbed. The key findings are as follows. (1) The proposed LSFR is divided into three modules and becomes an inclined plane by moving the modules at both ends. Moreover, combined with light shelf angle control, the LSFR enables control over the direction of daylight inflow through light shelf reflection. (2) This study determines the optimal angle for a flat light shelf with angle control, highlighting the need to adjust the angle based on the external environment to enhance daylighting efficiency. (3) Upon implementing the optimal specifications, the LSFR reduces lighting energy consumption by an average of 49.5% and enhances the indoor uniformity ratio by 20.1% compared with Case 2 (flat light shelf with angle control). Particularly, the LSFR achieved a satisfactory 300 lx illumination without using additional lighting under the environmental conditions set in this study, which demonstrates the effectiveness of Case 3.
•This study derives optimal light shelf specifications.•The study also investigates factors that reduce daylighting performance.•A folding reflector technology based on the solar azimuth is proposed.•Algorithm to control the light shelf using folding reflector technology is proposed.•The proposed technology's is effective in improving daylighting performance.