Impact of window design variants on lighting and cooling loads: clues for revisiting local building regulations

The study is placed within the context of local building regulations in India. Building regulations, for fenestration in general and window openings in particular, are, to a large extent, ambiguous in nature. In the context of India, observations show that the regulations specify window size for the sole purpose of ventilation whereas windows are major roleplayers in the thermal and daylighting performance of buildings. In this paper, parametric simulation is used to generate data for cooling and lighting loads for typical commercial office spaces in the hot-dry climate of Ahmedabad, India. This data is then analysed using Multiple Regression techniques to express loads as a function of floor area, aspect ratio, window-to-wall ratio and orientation of windows. The equations derived from regression help compare the energy implications of varying window sizes and their orientations. The observations and results stress the need to re-analyse local building regulations as they fail to indicate the maximum allowable limit of window size leading to highly inefficient building design.