A simulation assessment of the height of light shelves to enhance daylighting quality in tropical office buildings under overcast sky conditions in Dhaka, Bangladesh

The objective of this paper is to highlight the effectiveness of light shelves in tropical office buildings to enhance interior daylighting quality. Daylight simulation was performed for custom light shelves for a typical office floor of Dhaka City in Bangladesh, to determine the best possible location under overcast sky conditions. Six alternative models of a 3m high study space were created with varying heights of light shelves. The 3D models were first generated in the Ecotect to study the distribution and uniformity of daylight in the interior space with split-flux method. These models were then exported to a physically-based backward raytracer, Radiance Synthetic Imaging software to generate realistic lighting levels for validating and crosschecking the Ecotect results. The results showed that for achieving light levels closest to specified standards, light shelves at a height of 2m above floor level perform better among the seven alternatives studied including the alternative where no light shelves are present. Finally, the decisions were verified with DAYSIM simulation program to ensure the compliance of the decisions with dynamic annual climate-based daylight performance metrics.