The Impact of Shading on Building Day lighting and Energy Consumption

Window is an important channel for utilization of daylight and communication with the nature. However, large window area usually results in excessive solar gains and glare problems, especially for south-facing facades of office buildings. Shading devices are believed as an effective implement to balance the requirements of daylight and the need to reduce solar gains. In this paper, the glazing and shading properties of south-facing facade of a simple office building have been taken as control variables. The integrated impact of glazing and shading properties on building daylighting and energy consumption was calculated by using daylight and thermal simulation module in ECOTECT and DOE respectively. The impact of window-to-wall ratio, height-to-width ratio, the height of windowsill on building energy consumption and indoor daylight were analyzed. The simulation results indicate that appropriate glazing and shading design in conjunction with simultaneous control of electric lighting components could significantly reduce energy consumption, while maintaining good thermal and visual indoor conditions. The optimum energy performance can be achieved at certain shade transmittance values, which is depending on window-to-wall ratio, climatic conditions and orientation. The selection of the height of windowsill must base on the depth of the room. For the room with very long depth, dividing the room into two areas (near and away from the window) for lighting control is suggested.