Calculate the rat at which heat would be lost on a very cold winter day through a 6.2 m× 3.8 m brick wall 32 cm thick. The inside temperature is 26ºC; assume that the thermal conductivity of the brick is 0.74 W/m .K.

Area of the brick wall,
A = 6.2 m × 3.8 m
= 23.56 m²
Temperature difference, ΔT = (inside temperature) – (outside temperature)
= 26° C – (-18° C)
= 44° C
= (44+273) K
= 317 K
Thickness, Δx = 32 cm
= (32 cm) (1 m/100 cm)
= 0.32 m