Question

A properly installed window quilt can provide an additional insulation of R-4 to windows. For a window with a U-factor of 0.33, determine the percentage of heat lost for a quilt-covered win- dow compared to a bare window.

Answer 1

Heat loss 67%.

Step-by-step explanation:

We know that heat transfer

Q=AUΔT

Where U is the overall heat transfer coefficient ,A is the area and ΔT is the temperature difference.

Now heat transfer in terms of U-factor

`Q_1=AU_1ΔT`

`Q_2=AU_2ΔT`

Given that temperature difference is same in both condition so

`(Q_1)/(U_1)=(Q_2)/(U_2)`

`(Q_1)/(Q_2)=(U_1)/(U_2)`

`heat\ loss=(Q_2-Q_1)/(Q_1)`

`heat\ loss=(U_2-U_1)/(U_1)`

Given that
`U_2=0.33U_1`

`heat\ loss=(0.33U_1-U_1)/(U_1)`

Heat loss 67%.