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

Answer:

Heat loss 67%.

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

$\dfrac{Q_1}{U_1}=\dfrac{Q_2}{U_2}$

$\dfrac{Q_1}{Q_2}=\dfrac{U_1}{U_2}$

$heat\ loss=\dfrac{Q_2-Q_1}{Q_1}$

$heat\ loss=\dfrac{U_2-U_1}{U_1}$

Given that$U_2=0.33U_1$

$heat\ loss=\dfrac{0.33U_1-U_1}{U_1}$

Heat loss 67%.