A window of a skyscraper consists of three layers of 7.5mm thick glass (k=0.18 W/mC). The first two layers are separated by a 5.5mm wide stagnant air space (k= 0.026W/mC ). The window is 5m high and 3m wide. If the temperature inside the building is maintained at 25C while the temperature outside is 12C. Take the convection heat transfer coefficients on the inner and outer surface of the window to be h=9W/m2C. Determine the rate of heat transfer through the window. [20 Marks]