Window to Wall Ratio for Day Lighting in Context of Apartment Building in Kathmandu Valley

Abstract

Day lighting is a required admission of natural light into an enclosed space for proper visibility and reduction or elimination of electric lighting. Day lighting is provided by the use of windows or any transparent or translucent surfaces. Provision of natural day lighting helps to create healthy living and working environment and to reduce the energy consumption of any building. Some of the main passive design factors that controls the admission of day light are window to wall ratio, fenestrations, orientation, shading devices, louvers and climatic condition. In this research, Window to wall ratio is considered to optimize day lighting inside a room of an apartment building located in Kathmandu valley. The study was carried out by simulation using VELUX Daylight Visualizer software. The analysis was performed for a habitable room model with 4.6 m x 3.3m x 3.3m dimensions. Window to wall ratio 10% to 30% was considered for analysis. The result shows that minimum window to wall ratio required for better illuminance and distribution of daylight from the window inside the room is 24%.