The effect of the cover and reflective properties of a four-sided atrium on the behaviour of light

From a natural lighting standpoint, the atrium envelope acts as a filter between the outdoor environment, the atrium light well and the spaces around it. On its passage through the atrium cover, a portion of the incoming daylight is directed towards the adjacent rooms and the other is inter-reflected between the atrium surfaces and channeled downward towards the lower floors. The amount of daylight reaching the adjacent spaces depends largely on how much light is transmitted from the outside, the size of opening within the atrium walls and the inter-reflection capability of the atrium. In this study we have examined the effect of roof configuration and the reflective properties of the atrium intermediate boundaries on the behaviour of light along the atrium walls. The investigation was limited to a top-lit atrium and results indicate that the reflective characteristics of the atrium walls can significantly affect the intensity that reaches the lower levels of the atrium. Floor reflectance has a significant daylighting effect but it is limited to the lower floors only. The design parameter that had the most significant daylighting effect is the type of roof cover.