How do you calculate thermal load for a window?

The formula used to calculate thermal load for a window is based on the relationship between the area of the window, the U-factor, and the temperature difference (ΔT) across the window. The correct method involves using the U-factor, which represents the thermal transmittance of the window.

The calculation is typically represented as:

Thermal Load = Area × U-factor × ΔT

In this formula:

• The area represents the square footage of the window.

• The U-factor indicates how well the window insulates; lower U-factors signify better insulation.

• ΔT is the difference in temperature between the inside and outside of the building.

Using the U-factor with the area and temperature difference gives a clear quantification of heat loss (or gain) through the window, which is essential for accurately sizing heating or cooling equipment.

The other methods presented do not effectively capture the necessary factors that contribute to thermal load through a window. For example, utilizing the Solar Heat Gain Coefficient (SHGC) alone, as suggested in one of the options, only considers solar heat gain, which does not encompass the complete thermal profile. Options involving division or addition are not applicable to the principles of thermal load calculation, as they do not relate back to heat