The Effect of Light Shelf and Translucent Ceiling on Daylighting Performance in Office Building in Thailand

Abstract

Daylight control strategies were a challenge for a high-rise building in terms of savingenergy consumption. Light shelf was one of the daylight control systems which was usuallyhorizontal or inclined surfaces, placed on the inner and/or the outer side of windows toreflect sunlight to ceiling and distribute the light deeper into the room. This study aimedto investigate the performance of daylight control strategies in office rooms using alight-self with translucent ceiling. The light shelf, which is typically horizontal or inclined,was placed on the inner or outer side of windows to reflect sunlight and distribute itdeeper into the room. The study investigated the effect of type of daylight techniqueswhich are a combination of different light shelves and translucent ceiling on daylightingperformance. The illuminance level in an office room was calculated using DIALux 4.13 andwas performed for working hours in Bangkok, Thailand. The simulation was performedunder clear sky conditions and using real climatic data from four orientations. Fivetypes of daylight techniques, including the existing room, were investigated in terms ofilluminance level and uniformity of daylight in the office room. The CIBSE (2015) and IESNA(2011) standards indicate that offices room should have uniformity of at least 0.8 andan illuminance level of 500 lux. Thus, the objective of this research was to determine thebest combination of light shelves and translucent ceilings for achieving illuminance anduniformity standards. The results showed that the external light shelf with a translucentceiling and static louver at 90o (option 4) was the best solution for office rooms, providingaverage illuminance level 776 lux (above the standard) and uniformity 0.4 (nearly thestandard). This conclusion suggests that a light-shelf with a translucent ceiling guidesdaylight deep into the room but less uniformity.