Question

A room contains four single-pane windows of size 5 ft by 2.5 ft. The thickness of the glass is 1/4 in. If the inside glass surface is at 60°F and the outside surface is at 30°F, estimate the heat loss through the windows 0HT

Answer 1

Explanation:

The given data is as follows.

           Area = $5 ft \times 2.5 ft$ = 12.5 $ft^{2}$

             L = 0.25 in = 0.0208 ft     (as 1 inch = 0.0833 ft)

      $T_{s, in} = 60^{o}F$,         $T_{s, out} = 30^{o}F$

               k (thermal conductivity) = 0.8 $Btu/hr-ft-^{o}F$

Formula to calculate the heat loss will be as follows.

               Q = $k \times A \times \frac{T_{s, in} - T_{s, out}}{L}$

Putting the given values into the above formula as follows.

             Q = $k \times A \times \frac{T_{s, in} - T_{s, out}}{L}$

                 = $0.8 Btu/hr-ft-^{o}F \times 12.5 ft^{2} \times \frac{60^{o}F - 30^{o}F}{0.0208 ft}$

                 = 14285.7 Btu/hr

So, $Q_{net} = 4Q$

                  = $4 \times 14285.7$

                  = 57142.8 Btu/hr

Thus, we can conclude that heat loss through the windows is 57142.8 Btu/hr.