Energy efficiency criterion for increasing the area of the window

Taking advantage of the potential of daylighting in the building helps to save energy used for artificial lighting. In Russia and other countries, where most of the energy is consumed for heating in winter, the increased window area leads to a reduction in the energy costs of artificial lighting but increases the heat loss through the windows blocks. Some studies contain criteria for assessing the feasibility of increasing the area of window, however, the influence of artificial light sources have not included. In this paper, the thermal balance of the room is considered, including the influence of artificial light sources, heat gain from solar radiation and transmission heat loss through window blocks. By calculating the difference in the thermal balance of the room after and before the increase in the window area, an expression of the criterion for evaluating the benefits of increasing the window area by energy indicators was obtained. Based on the cost of heat and electricity, the expression of the criterion for assessing the benefits of economic indicators was proposed. According to the presented criteria, the calculation for different function spaces: residential, office and school classes designed for Moscow was carried out. It is shown that, according to energy indicators, an increase in the window area is unprofitable or low profitable for residential and office premises, but beneficial for the school class. In conclusion, the paper shows the possibility of evaluating the energy efficiency of increasing the area of the window using the developed criteria.