Heat loss and cooling load calculators based on CSA F280 and Canadian city design temperatures. Covers all provinces.
Furnace Sizing Calculator
Fuel Bill MethodReplacing your furnace? Size it from your actual gas bill — no R-values or blueprints needed. More accurate than rules of thumb for existing homes.
Open calculatorHeat Load Calculator
CSA F280New home or renovation? Calculate design heat loss using CSA F280 — enter insulation levels, city, and floor area.
Open calculatorCooling Load Calculator
CSA F280 / ASHRAEHow many BTUs to cool my home? Calculate cooling load for Canadian summers and size your AC correctly.
Open calculatorAC Size Calculator
Canadian Design TempsWhat size air conditioner do I need? Get a BTU recommendation for your home based on floor area, insulation, and your city's cooling design temperature.
Open calculatorHVAC sizing in Canada requires Canadian design temperatures — not US climate data. CSA F280-12 (Determining the Required Capacity of Residential Space Heating and Cooling Appliances) defines the method used by Canadian HVAC engineers and is referenced in provincial building codes. A furnace or heat pump sized using US Manual J inputs will be wrong for Canadian winters, particularly in Ontario, the Prairies, and northern regions where design temperatures reach −25°C to −40°C.
This hub offers two approaches to heat loss depending on your situation. For new construction or major renovations, the Heat Load Calculator uses the CSA F280 method — you enter insulation R-values, window area, airtightness class, and city to get a design heat loss in BTU/hr. For existing homes, the Furnace Sizing Calculator uses your actual gas or propane bill to back-calculate what your home already loses in heat — often more accurate than R-value estimates for older houses with unknown insulation levels.
The Cooling Load Calculator estimates summer peak cooling demand for central AC and heat pump sizing, adapted for Canadian cities and their July design temperatures sourced from NBCC 2020 Appendix C.
Heat loss calculations are most commonly needed in Ontario (design temps from −15°C in Toronto to −24°C in Thunder Bay), Alberta (−33°C in Edmonton), Quebec (−23°C in Montreal), and BC (−8°C in Vancouver to −29°C in Prince George). All city data used in these calculators is sourced from NBCC 2020.
Read our guide: How to Use a Heat Loss Calculator for Canadian Homes →