Chapter 1, Problem 1.9P

A glass window of width $W=1\text{m}$ and height $H=2\text{m}$ is 5 mm thick and has a thermal conductivity of $k_g=1.4\text{W/m}\cdot \text{K}$ . If the inner and outer surface temperaturesof the glass are 15°C and $-\text{2}0°\text{C}$ , respectively, on acold winter day, what is the rate of heat loss through theglass? To reduce heat loss through windows, it is customary to use a double pane construction in whichadjoining panes are separated by an air space. If thespacing is 10 mm and the glass surfaces in contact withthe air have temperatures of 10°C and $-15°\text{C}$ ,whatis the rate of heat loss from a $\text{1 m}\times \text{2 m}$ window? Thethermal conductivity of air is $k_a=0.024\text{W/m}\cdot \text{K}$ .