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Energy test guide · verified October 2, 2026
Before anyone sells you a heat pump or furnace, someone should calculate — room by room, to the CSA F280 standard — how much heat your house actually loses on the coldest design day. Contractors who skip it size by square footage and habit, and habit oversizes. Oversized equipment costs more, cycles hard, dehumidifies poorly, and never feels right.
Wall, window, ceiling and foundation areas with their real insulation values — ideally pulled straight from your EnerGuide assessment file, which is why bundling the calculation with the audit is both cheaper and more accurate than a standalone guess.
Every Canadian locality has a design temperature: the cold your heating must handle on a design winter day, from the National Building Code's climate tables. The calculation runs your envelope against that number, not a national average.
Your blower door number feeds in (leaky homes lose more), along with internal and solar gains. This is what separates F280 from a square-footage rule of thumb.
Not just a house total: each room's need in BTU/h. This is what exposes why the far bedroom never worked — and whether the fix is ducting, not a bigger furnace.
Heat pump capacity tables at cold temperatures get compared to your load: what the unit delivers at −8°C and at design temperature, and what backup covers the gap. The equipment decision becomes arithmetic instead of salesmanship.
Energy advisors and qualified HVAC designers run F280 calculations; ask for the report by name, and expect $150–$400 standalone or less bundled with an assessment. The tell that you need it: a contractor who quotes equipment size from your square footage, your old furnace's label, or a walk-through glance.
What the number is: Installed heating or cooling capacity as a percentage of the room-by-room design load (CSA F280 heat-loss calculation).Unit: % of design load (W or Btu/h)
What it means: Within ACCA Manual S limits; the system can meet design conditions without excessive cycling.
What to do: Go ahead; check the quote lists the load calculation and the unit's capacity at design temperature.
What it means: Costs more, short-cycles and gives temperature swings and drafts; a heat pump may miss its expected savings.
What to do: Ask for smaller or variable-capacity equipment chosen from the room-by-room calculation.
What it means: A furnace may not keep up on the coldest days; a heat pump will lean more on backup heat.
What to do: Confirm the backup heat plan and expected use, or choose a larger or cold-climate model.
NRCan recommends a recognized load method such as CSA F280-12. Manual S percentages are a US benchmark; ask your designer which sizing limits they used.
The calculation's 'issue' is usually a mismatch — between quotes, or between your house and what's installed. The options:
Often saves money
The most common outcome: the correct unit is smaller and cheaper than the habit quote. Never let the old furnace's size set the new one — the old one was probably oversized too, and your envelope may have improved since.
Sequencing, not spending
Air sealing and insulation reduce the number — done before equipment replacement, they let you buy a smaller heat pump. This is the whole logic of the retrofit sequence: envelope, then equipment.
Design choice
Size the heat pump for most of the winter and let backup (electric or existing furnace) carry the coldest tail — often the economic optimum in cold climates, and only calculable with a real load number.
See duct testing
When one room fails but the house total is fine, the answer is airflow — ducts, returns, balancing — not a bigger machine pushing harder through the same bad ducts.
Keep the F280 report with your quotes. A contractor who welcomes it is a contractor worth shortlisting; one who waves it off told you something useful too.
Rules of thumb by square footage, fear of cold-day callbacks, and matching whatever was there before. The incentives all point to bigger, and none of them price in what oversizing costs you: short cycling, worse humidity control, more noise, higher purchase price, and — for heat pumps especially — efficiency lost to constant starts.
No. A right-sized system runs long, steady, quiet cycles that hold temperature and wring out humidity. An oversized one blasts, satisfies the thermostat, and shuts off — repeatedly. For heat pumps, sizing to the real load is the difference between the technology working as advertised and a disappointing winter.
Program rules vary and change, but the practical answer: heat pump incentive paths run through the EnerGuide assessment, and quotes built on a real load calculation are what a registered advisor can stand behind. Ask your advisor which current programs expect the F280 paper — and get it regardless, because the equipment is yours for 15+ years either way.
Tell us you're considering a heat pump — we'll match you with an advisor who runs the F280 numbers before the sales visits start.