A wall of a building is 15 m long and 4 m high. It has a 9 mm thick gypsum board (k = 0.16 Wmí1 Kí1 ) on the inside. Next to it is a 140 mm thick layer of glass fiber insulation (k = 0.046 Wmí1 Kí1 )...

A wall of a building is 15 m long and 4 m high. It has a 9 mm thick gypsum board (k = 0.16 Wmí1 Kí1 ) on the inside. Next to it is a 140 mm thick layer of glass fiber insulation (k = 0.046 Wmí1 Kí1 ) which is followed by a 180 mm thick layer of concrete (k = 2.1 Wmí1 Kí1 ). The outer face is made brick (k = 1.35 Wmí1 Kí1 ) with a thickness of 100 mm. The outside and inside heat transfer coefficients are 28 Wmí2 Kí1 and 8 Wmí2 Kí1 respectively. The inside and outside air temperatures are 23°C and 2°C respectively. Calculate (i) the total thermal resistance, (ii) the overall heat transfer coefficient, and (iii) the total heat transfer rate through the wall.