Evaluation of Thermal and Visual Performance of Windows in Classrooms of Tehran

Providing suitable environmental conditions for educational buildings has always been critical because of the negative influence of thermal and visual discomfort on students’ learning and performance. Unsatisfactory conditions mostly caused by overheating and glare due to the presence of direct solar radiation, could be compensated by appropriate window configurations. Since occupants are obliged to sit in designated positions in classrooms, spatial analysis of the thermal and visual field are necessary in addition to temporal evaluations. This paper applies both spatio-temporal thermal and visual comfort metrics, to assess the effect of window design on comfort by dynamic simulations in a typical classroom model in Tehran’s climatic condition. In addition to comfort the primary energy demands have also been assessed in different window types. Presented graphs can be used to select the optimum window based on the desired window-wall ratio and orientation. According to results high performance windows with high LSG provide spatio-temporal thermal comfort in all orientations considering a WWR of less than 35%. However, spatio-temporal visual comfort is not achieved without external shadings except in the north-facing windows. Results show solar-control coated glazing (low SHGS) with high VT can be used as an alternative to solar shadings, wherever exterior shading is neither permitted, nor possible.