The exterior wall of a building consists of concrete blocks (k = 1.6 Wmí1 Kí1 ) of thickness 80 mm, and an insulation layer (k = 0.12 Wmí1 Kí1 ) of thickness 15 mm. The exterior surface of the...

The exterior wall of a building consists of concrete blocks (k = 1.6 Wmí1 Kí1 ) of thickness 80 mm, and an insulation layer (k = 0.12 Wmí1 Kí1 ) of thickness 15 mm. The exterior surface of the concrete absorbs solar radiation at the rate 400 Wmí2 . The outside and inside heat transfer coefficients are 20 Wmí2 Kí1 and 6 Wmí2 Kí1 respectively. The outside and inside air temperatures are 28°C and 18°C respectively. Calculate (i) the outside wall surface temperature and (ii) the rate of heat flow into the air inside.