Chapter 3, Problem 165P

Consider a house with a flat roof whose outer dimensions are $\text{12 m × 12 m}\text{.}$ and The outer walls of the house are 6 in high. The walls and the roof of the house are made of 20-cm-thick concrete $\left(k=0.75\text{ W/m}\text{.K}\right)$. The temperatures of the inner and outer surfaces of the house are 15°C and 3°C, respectively. Accounting for the effects of the edges of adjoining surfaces. determine the rate of heat loss from the house through its walls and the roof. What is the error involved in ignoring the effects of the edges and corners and treating the roof as a $\text{12 m × 12 m}$ surface and the walls as $\text{6 m × 12 m}$ surfaces for simplicity?