The Efficacy of Horizontal Adjustable Bent Louver Shading for Enhancing Daylighting Performance in Walk-Up Apartment Buildings

This paper addressed the challenges posed by the limited windows and restricted areas in walk-up flats in Indonesia, resulting in improper indoor daylight performance. The study proposes using outdoor horizontally bent, adjustable louver screens as daylight reflectors to overcome this issue and improve daylighting performance in apartment buildings. The quasi-experimental technique implemented the Radiance Desktop Plug-in Version 1.02 and Ecotect 2011 lighting software. Variables, such as slat shading geometry, i.e., flat, one-bent, two-bent slats, and rotation opening angles, i.e., 30^o, 45^o, 60^o, and 90^o, were examined for interior daylight performance regarding daylight intensity and distribution. The findings indicate that although shading can reduce the average lighting level in a room, shading types with bents can improve daylight performance in another important aspect, namely achieving a more even distribution. The most effective shading technique for harvesting and distributing daylight evenly in tropical walk-up apartments was a two-bent slat type, particularly with opening angles of 90^o. The results also demonstrate that louvers with multiple bent slat geometry are particularly effective in reflecting high altitudes of incident light often encountered in tropical regions and scattering the incoming light evenly into the innermost area of the room.