Application of Daylight Simulation in Detailed Design Process: Distribution of Skylights for an Office Space under Overcast Sky Conditions in Dhaka

Abstract

During design phase, architects often uncertain about the actual environmental performance of architectural details under the local climatic condition. In most of the cases architect, owner and users have to wait till the completion of the construction of the building and full occupancy to understand the performance. The building simulation software can help an architect to visualize and conceptualize the actual performance of the details and helps in decision making process to progress with design details during preliminary design phase. This paper presents a thorough case of application of daylight simulation in detailed design process by analyzing different distribution of skylights for maximum utilization of daylight to illuminate interiors. Daylight simulation was performed in this study by creating a virtual environment based on the information of an existing urban office building located in Dhaka, Bangladesh, a tropical location, with predominantly overcast skies. The 3D models were first generated in the ECOTECT, to study the distribution and uniformity of daylight at the interior space, using the split-flux method. These models were then transferred to a physically-based backward raytracer, RADIANCE Synthetic Imaging software, to generate realistic lighting levels, for validating and crosschecking the ECOTECT results. The results show that, providing skylights in the roof can allow a huge amount of daylight into the workspace, therefore, need further detailing. A sensible distribution and rearrangements could help to ensure better illuminance and luminance distribution at the top floor. This paper also demonstrates a case of decision-making to do further details to reduce the glare and overheating possibility into the workspace. The focus of the paper is to highlight the importance of daylight simulation to progress with design details during preliminary design phase, while at the same time gives a general methodology for decision-making regarding daylight design elements.