Homeowners and HVAC technicians use heat loss calculations to determine the size of the heating system needed to maintain comfortable indoor environment using less energy. In order to calculate the heat loss or gain of a particular house. This complicated mathematical process takes into account all the factors that can affect the heating in a house.

Calculate the design temperature (DT) for the house, using the formula DT = IT – OT. The design temperature takes into account their preference for the internal temperature (IT) and the average outside temperature (OT) for their region. For example, if OT TI = 75 = 65, the home DT is 10. Get a copy of your house plans clearly marked dimensions for walls, windows, doors and ceilings. Use a tape measure to determine the dimensions not covered by housing plans.

The formula for surface area is SA = height x width. It may be helpful to label each door and window in the house plans and create a separate list. Write the area of ​​each window next to the label for quick reference in subsequent calculations. Calculate the surface area (SA) of an exterior wall of the house. Calculating the surface area of ​​an exterior wall surface area subtracting doors or windows on that wall. The formula for the surface area of ​​an exterior wall is SA (wall) = (height x width) – SA (gate) – SA (window). If more than one window or door, subtracting the surface area of ​​each window or door in the wall. Repeat the calculation of the surface area of ​​each exterior wall of the house.

Calculate the value U (UV) to the walls, doors, windows and roof of the house. U value is typical heat loss of a particular surface in the home. The formula for the value U is UV = 1 / R-value, where the value R is the potential of a surface insulation. If you do not know the R-value of windows, doors or insulation in your home, see Resources for a list of typical R-values. Calculate the surface heat loss (SHL) using the formula SHL = U xx SA DT value. Calculate the heat loss from the surface of each wall, window, door and ceiling. Add the surface heat loss for each wall, windows, doors and roof. This equals the total heat loss for the home.