Study of Optimum Inward Glass Tilt Angle for Window Glass in Different Indian Latitudes to Gain Minimum Heat into Buildings

Abstract

Modern buildings use glass materials for building enclosures. Extensive use of glass in building envelopes increases the heat gain, which in turn increases the energy demand to maintain the building at comfortable conditions. This paper presents experimentally measured spectral optical properties of four different glass materials such as, clear, bronze, green and reflective glasses. The solar optical properties were computed using spectral optical properties. The effect of inward glass tilts to gain minimum heat into buildings for different latitudes of India with four different glass materials for energy efficient glass window design was studied.. The optimum glass tilt for different Indian latitudes such as, 90, 130, 170, 210, 250 and 290 in all orientations of the window glass (E, W, N, S, NE, NW, SE and SW) were computed. From the results it is observed that at 90 and 170 N latitudes minimum heat gain is found to be in south direction for the vertical position of all the glasses. For 130 N latitude, 40 inward tilt of the glass is observed to be optimum in south direction. For latitudes 210 and 250 N, 20 inward tilt of the glass is efficient in south orientation. 290 N latitude requires an inward tilt of 60 for glass materials to eliminate solar radiation passing through the glasses in south direction.