The thickness of a basement wall made of concrete (k = 2.1 Wmí1 Kí1 ) is 210 mm. It is insulated on the inside with a layer of polystyrene insulation (k = 0.04 Wmí1 Kí1 ) of thickness 40 mm, and...

The thickness of a basement wall made of concrete (k = 2.1 Wmí1 Kí1 ) is 210 mm. It is insulated on the inside with a layer of polystyrene insulation (k = 0.04 Wmí1 Kí1 ) of thickness 40 mm, and finished with gypsum board paneling (k = 0.16 Wm-1K-1) of thickness 8 mm. The total horizontal length of the wall is 80 m and it extends 2 m below grade. The soil surrounding the wall has a thermal conductivity of 1.3 Wmí1 Kí1 . The inside air temperature is 17°C and the outside ambient temperature is í2°C. The inside and outside heat transfer coefficients are 9 Wmí2 Kí1 and 30 Wmí2 Kí1 respectively. Calculate (i) the average heat transfer coefficient for the basement wall, and (ii) the total rate of heat loss through the basement wall.