Key Takeaways
- An undersized heat pump runs continuously without maintaining setpoints during winter cold snaps.
- Over-sizing leads to rapid short-cycling, accelerating compressor wear and reducing summer dehumidification.
- As a general Quebec rule of thumb, target 20 to 25 BTU per square foot of living space for standard insulation.
Basic sizing formula for the Quebec climate
To estimate capacity, multiply living area square footage by a thermal factor of 20 to 25 BTU per sq ft.
For example, a 1,600 sq ft home built in the 1990s requires roughly 1,600 x 22 = 35,200 BTU/h heating output, matching a 3.0-ton (36,000 BTU/h) unit.
Key variables impacting heat load calculations
Square footage is only part of the equation: construction vintage, ceiling heights, window surface area, and solar exposure alter thermal demand.
Newer energy-efficient homes built after 2012 require up to 30% fewer BTUs per sq ft than homes built prior to 1980.
Why heating capacity at -8 °C determines LogisVert grant amounts
Hydro-Québec LogisVert calculates subsidies strictly from certified heating capacity at -8 °C, rather than rated summer cooling capacity.
Review the manufacturer AHRI certificate with your contractor to verify your exact grant tier.
Estimate your rebates & energy savings
Access our self-serve calculator or get a free, direct match with a qualified local contractor.