Sky Obstruction and Daylight: Using the preferable sky window to urban daylight analyses

The urban environment can cause obstruction of the sky thereby affecting sunlight and daylight availability on the building fenestration and also further inside the building. This study uses the Preferable Sky Window (PSW) parameter to analyze daylighting availability in different urban scenarios with the objective to obtain some basic guidelines for daylighting access in urban environments. The PSW consists of a sky zone which identifies the sky section that has the greatest daylight potential in a horizontal plan located in the indoor environment. The scenarios with the most unobstructed PWS parameter were assumed to have the most daylight availability. The urban scenarios tested consisted of a fixed volume of buildings located in a pre-determined plot area. A computational daylighting simulation was also performed to correlate the PSW obstruction with the indoor daylighting performance. Daylighting simulation and PSW analyses were performed using Apolux code. According to this work, guidelines can be developed restricting building height and spacing in order to provide minimum standards of daylight availability. However, the same rules cannot be directly applied when the occupation pattern is not the same.