Residential Heat Gain Calculator
Heat Loss · Disclaimer · Air Flow
ASHRAE Climate Zone
Stories
Floor Area (ft²)
Ceiling Height (ft)
Indoor Temp (°F)
Outdoor Temp (°F)
Same wall construction and R-value for all exterior walls. Enter gross wall area per orientation (windows on the next step).
Wall Construction
Wall R-Value
North Wall Area (ft²)
South Wall Area (ft²)
East Wall Area (ft²)
West Wall Area (ft²)
Optional. Leave blank for no windows — heat load still calculates.
North
Window Area (ft²)
Glazing
South
Window Area (ft²)
Glazing
East
Window Area (ft²)
Glazing
West
Window Area (ft²)
Glazing
Diagonal glass (NE/NW and SE/SW) for solar gain.
NE + NW Window Area (ft²)
Window Glazing
SE + SW Window Area (ft²)
Window Glazing
Total Door Area (ft²)
Construction
Ceiling / attic
Ceiling Area (ft²)
Ceiling R-Value
Attic Temp (°C)
Attic Type
Attics can exceed 50°C on hot days.
Floor / slab
Floor Area (ft²)
Floor R-Value / Type
Number of Occupants
Internal Loads (W)