Ontario · Energy · checked September 28, 2026

Heat loss calculations in Ottawa

The heat loss calculation is how a heat pump or furnace gets sized for your house, and the key input is the design temperature: −24.3°C for Ottawa, from NRCan's HOT2000 climate data for Ottawa International.

Get matched in Ottawa → The CSA F280 heat-loss calculation
A kitchen table with a house floor plan, a laser measure, a tape measure and a laptop showing the plan

Design temperature

−24.3°C

Heating degree-days

4,354

Standard

CSA F280

Typical cost

$150–$400 standalone

How Ottawa is built

Ottawa's houses by when they were built Ten house shapes, one for each tenth of Ottawa's 287,345 houses. Before 1961: 16%, 1961–1990: 40%, 1991–2000: 13%, 2001 or later: 32%. Older houses glow hotter.
  • Before 1961 16%
  • 1961–1990 40%
  • 1991–2000 13%
  • 2001 or later 32%
Each house stands for one in ten of Ottawa's 287,345 houses (single-detached, semi-detached, row and duplex), drawn by when it was built. The glow shows the usual pattern: older houses tend to be leakier and less insulated. Snowfall scales with heating degree-days. Sources: Statistics Canada 2021 Census (table 98-10-0233-01), NRCan HOT2000 climate data.

Why the design temperature matters in Ottawa

−24.3°C is the 19th-coldest design temperature of the 70 cities we cover. The F280 calculation works out how much heat each room loses on that design day, from the house's actual walls, windows, air leakage and ceiling insulation.

At −24.3°C, a cold-climate heat pump sized to the calculation can carry most of the season, and the number shows how much backup heat the coldest days need.

In the Ottawa (Ontario) part of the Ottawa–Gatineau region, 69% of households heat mainly with a forced-air furnace, 10% with electric baseboards and about 6% with a boiler and radiators; natural gas is the main heating energy for 59% of households and electricity for 21% (Statistics Canada, 2023).

Why skipping it costs money

Contractors who size by square footage routinely oversize. An oversized heat pump costs more to buy, cycles on and off, dehumidifies poorly in summer and wears faster. An undersized one leans on backup heat. The F280 report is the evidence either way, and it's worth having before you compare quotes.

What it costs

About $150–$400 as a standalone calculation (a September 2026 planning range; quotes vary). Many energy advisors bundle it with an EnerGuide evaluation, which also gives the calculation measured air-leakage data instead of an assumption.

NRCan-licensed service organizations serving Ottawa

Many energy advisors also do room-by-room CSA F280 calculations for an extra fee; HVAC designers do them too. Ask for the F280 report itself, not just an equipment recommendation.

Only assessments from the seven HRSP-approved organizations qualify for the $600 Home Renovation Savings rebate and its assessment-path upgrade rebates; each listing below says whether it's one of them.

Source: NRCan list of licensed service organizations, checked September 28, 2026. Call to confirm your street is covered and ask about wait times.

Heat pump programs in Ottawa

Provincial · needs an evaluation Home Renovation Savings — Home Energy Assessment path Up to $10,000 per home for insulation, windows and air sealing, plus $600 back on your assessments — if the follow-up assessment is done by December 31, 2026 Open · deadline Provincial Home Renovation Savings — direct rebates (no assessment) Heat pumps up to $7,500 ($12,000 ground-source), solar with battery up to $10,000, plus attic, thermostat and appliance rebates — no assessment needed Open Federal CMHC Eco Improvement premium refund 25% back on your CMHC mortgage insurance premium after $20,000 of energy renovations Open Municipal Better Homes Ottawa Loan Program City of Ottawa low-interest loan repaid on the property tax bill: 20-year term at 4.33% fixed, minimum $10,000, maximum $125,000 or 10% of the tax-assessed value (whichever is less), 4% administrative charge. Covers insulation, air sealing, windows, heat pumps, water heaters, solar PV, batteries, Level 2 EV chargers and more. Pre- and post-retrofit EnerGuide assessments required. Detached, semi, townhouse and multi-unit buildings of 3 storeys or less. Delivered with EnviroCentre (page updated July 2026, 'Enroll today'). Municipal Better Homes Ottawa Heat Pump Incentive City incentive for loan-program participants only: $700/ton for cold-climate air-source heat pumps (central or mini/multi-split; NRCan cold-climate list, 80%+ capacity maintenance, at least 12,000 BTU, 55 dB or less); ground-source $1,000/ton plus $5/m of vertical well depth or horizontal loop.

Heat loss calculation in Ottawa: common questions

What design temperature is used for heat pump sizing in Ottawa?

NRCan's HOT2000 climate data gives −24.3°C for Ottawa International. Your designer may use the building code's design value for Ottawa, which can differ slightly; ask which one the calculation uses.

How much does a heat loss calculation cost?

About $150–$400 standalone as a planning range; often less when bundled with an EnerGuide evaluation.

Who does F280 calculations in Ottawa?

Many of the 26 NRCan-licensed organizations serving Ottawa offer them, as do HVAC designers. Ask for the F280 report itself.

Do rebate programs require a heat loss calculation?

Requirements vary by program and change often. Even where it isn't required, it is the best protection against an oversized or undersized system.

Heat loss calculation near Ottawa

Heat loss calculation in Gatineau13 kmHeat loss calculation in Kingston139 kmHeat loss calculation in Laval155 kmHeat loss calculation in Montréal161 kmHeat loss calculation in Terrebonne163 km All 70 cities →

Sources

Checked September 28, 2026. Census figures are for the municipality (Ontario); climate data is NRCan's HOT2000 station Ottawa International (6 km away).

Get matched with a registered advisor in Ottawa

Tell us your postal code and what you’re planning. We’ll connect you with one licensed service organization serving your area. No spam, no shared lead lists.

Email us what you’re planning, your postal code and the type of building (a house, a duplex or triplex, or a larger multi-unit building) — we’ll reply with registered service organizations for your area and which rebates apply.

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