Glossary · Heating, cooling & ventilation
Heat-loss calculation (CSA F280)
Also called: heat-loss calc · F280 · CSA F280-12 · heat loss and heat gain calculation · room-by-room heat loss
A calculation of how fast a home loses heat on the coldest days it's designed for, used to size heating equipment; in Canada it follows CSA F280.
What it means
It adds up heat flow through walls, roof, floors, windows and doors plus air leakage and ventilation at the local design temperature, giving the heating capacity the house needs in BTU/h or watts. CSA F280, titled Determining the Required Capacity of Residential Space Heating and Cooling Appliances, covers both heating and cooling loads; the current edition, F280-12, was reaffirmed in 2025.
Why it matters in an audit
Sizing a heat pump or furnace from a proper heat-loss calculation, rather than matching the old equipment, avoids oversizing and helps rebate-funded upgrades perform as promised.
Typical numbers
Reference values with their sources. Your energy advisor’s report gives the figure for your own house.
| What | Value | Source |
|---|---|---|
| CSA F280 edition | F280-12, reaffirmed in 2025 | csagroup.org ↗ |
In Canada
NRCan recommends a professional CSA F280-12 calculation before choosing a heat pump.