A Study of Light Zone in Commercial Buildings

Assessing Energy Efficiency for Shading Devices

Abstract

This paper addresses the daylighting compromises of the passive architectural feature of sunshades, owing to the subdivision of varying illumination level of light zones into the interior luminous environment. In light zones, under and over-lit zones may cause visual and thermal discomfort, in addition to consequent energy consumption. However, using daylight, dependency on artificial lighting sources can be minimized, resulting in energy efficient sustainable buildings. This paper presents a simulation study of assessing the luminous performance of most commonly used shading devices, for recent tall office buildings of Dhaka. It emphasizes in the context of the most vulnerable—south, east and west orientation for this location—during the overheated period of summer. Six selected fixed external shading devices, from a field survey, have been evaluated, based on the light zone distribution. The simulation results indicate that both the geometrical, as well as the material characteristics of shading devices, can have a noteworthy influence on the desired luminous performance. The results also clearly illustrate the necessity of selecting proper shading devices to modify the dimensional relations of the light zone and enhance energy efficiency in offices of similar tropical areas.