Residential Heat Loss Calculator
Heat Gain · Disclaimer · Air Flow
ASHRAE Climate Zone
Stories
Conditioned Floor Area (ft²)
Ceiling Height (ft)
Indoor Design Temp (°F)
Outdoor Design Temp (°F)
Outdoor temp uses representative winter design values when a climate zone is selected. Edit for your local design conditions.
Enter total exterior envelope areas (not broken down by compass direction).
Wall Construction
Wall R-Value
Net Wall Area (ft²)
Total Window Area (ft²)
Window Glazing
Net wall area = gross exterior wall minus windows and doors.
Total Door Area (ft²)
Door Construction
Ceiling / Roof Area (ft²)
Ceiling R-Value
Attic / Roof Exposure
Floor Area (ft²)
Floor / Slab R-Value
Foundation Type
Air Changes per Hour (ACH)
Construction Tightness
Infiltration sensible loss uses 1.08 × CFM × ΔT. Mechanical ventilation can be added later as a separate line if needed.