How Thunder Bay is built
- Before 1961 43%
- 1961–1990 41%
- 1991–2000 7%
- 2001 or later 9%
What an evaluation finds in Thunder Bay homes
Of Thunder Bay's 37,935 houses (single-detached, semi-detached, row houses and duplexes), 43% were built before 1961 and 84% before 1991, according to the 2021 Census. The typical Thunder Bay house dates from 1961–1970, and an evaluation is how you find out what that means for yours: the blower door measures air leakage, the advisor inspects the attic, walls, basement, windows and heating system, and the report ranks upgrades by what they'd save.
Thunder Bay gets about 5,405 heating degree-days a year, a measure of how much heating its climate needs, and its winter design temperature, the cold day heating systems are sized for, is −28.6°C. Those figures come from the climate data for Thunder Bay in HOT2000, the home-energy software Natural Resources Canada (NRCan) gives energy advisors. That's the 9th-highest heating demand of the 70 cities we cover. Cold winters: heating is the biggest energy cost, so stopping leaks and insulating come first.
Thunder Bay also gets hot spells and heat waves, so plan how the house will stay cool: air sealing, attic insulation and shading help, and a heat pump adds efficient cooling.
In the Thunder Bay area, 84% of households heat mainly with a forced-air furnace; natural gas is the main heating energy for 81% of households (Statistics Canada, 2023). The heating system on the report shapes the recommendations: a forced-air furnace invites a ducted heat pump, electric baseboards a ductless one.
What it costs in Thunder Bay
Typical Ontario prices are about $500–$700 for the initial EnerGuide evaluation and $200–$450 for the follow-up, plus HST where it applies. Windfall Ecology Centre charges $500 + HST for the initial evaluation and $250 + HST for the follow-up, Reep Green Solutions charges $540 and $406 with no HST, and City-backed programs in Ottawa and London quote $500–$700 as typical for the first visit. Only assessments from the seven HRSP-approved organizations qualify for the $600 Home Renovation Savings rebate, and none of the seven publishes a price.
Most providers quote the initial (pre-upgrade) and follow-up (post-upgrade) visits separately. Rebate programs that pay on measured improvement need both, so ask for the combined price.
How a home energy assessment (EnerGuide evaluation) works
- Initial evaluation, about 2–3 hours. The advisor measures and inspects the house and runs the blower door test.
- Report and EnerGuide rating. You get the home's energy rating in gigajoules per year and a list of recommended upgrades with estimated savings.
- Do the work. Most rebate programs only count upgrades done after the initial evaluation.
- Follow-up evaluation. A second visit measures the improvement, which is what most rebates pay on.
Very Cold East Northern Ontario, Saguenay, Quebec City
Thunder Bay’s climate: Very Cold East
Deep, snowy winters: stop ice dams, and pair a cold-climate heat pump with backup heat.
Winters here are long and deep, with cold snaps of −25°C to −31°C and the heaviest snow loads of any region we cover. Heat escaping into the attic melts roof snow from below, which refreezes as ice dams. An EnerGuide evaluation here should focus on the attic, the basement and rim joists, and a heating plan with reliable backup heat.
In Thunder Bay: Thunder Bay ranked among Canada's highest-radon municipalities in the 2024 national survey, so test every home. Winters bring cold snaps near −31°C and heavy snow loads, so seal the attic and keep the gas furnace as backup to any heat pump.
Stop ice dams at the attic
NRCan says the best way to prevent ice dams is sealing attic air leaks and insulating thoroughly, so roof snow stays frozen. Snow loads here are the heaviest of any region we cover.
Cold-climate heat pump with reliable backup
Cold snaps of −25°C to −31°C are at or beyond many heat pumps' limits, so backup heat is a must: baseboards in most Quebec homes, the furnace in Ontario.
Insulate the basement and rim joists
Basements can be about 20% of a home's heat loss, and the long cold season makes the savings add up. Rim joists are often among the leakiest spots.
When to book: Book the evaluation from November to March for clear thermal scans, and check the attic after the first light snow. Start a 3-month radon test in the heating season.
Everything homes in Thunder Bay need →
Sources for this climate guide · checked October 26, 2026
- National Building Code of Canada 2020, climate data (NRC)
- Canadian Climate Normals 1991–2020 (ECCC)
- Keeping the Heat In (NRCan)
- Air-Source Heat Pump Sizing and Selection Guide (NRCan)
- Heating and Cooling With a Heat Pump (NRCan)
- Heat pumps, Canada Greener Homes (NRCan)
- Heat pump basics (NRCan)
- Primary heating systems by household, Table 38-10-0286-01 (Statistics Canada)
- 2024 Cross-Canada Survey of Radon Exposure
- Guide for Radon Measurements in Homes (Health Canada)
- Canada's top weather stories of 2023 (ECCC)
- Conditions for thermal scans, ASTM C1060 summary (Cx Associates)
NRCan-licensed service organizations serving Thunder Bay
A service organization is a company that Natural Resources Canada (NRCan) licenses to deliver EnerGuide evaluations; its registered energy advisors do the home visit. Every organization below is licensed by NRCan to deliver EnerGuide evaluations and lists Thunder Bay postal codes. Coverage is the share of Thunder Bay's urban postal areas each one lists.
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.
- Energy Werx HRSP-approved: Yes Profile
- Green Think HRSP-approved: No
- Greenbrain HRSP-approved: Yes Profile
- The Energuy HRSP-approved: Yes Profile
- All Season Inspection HRSP-approved: No Profile
- EnerSolution HRSP-approved: No Profile
- Sensible Home Inspections HRSP-approved: No
Rebates and financing an evaluation unlocks in Thunder Bay
Home energy audit in Thunder Bay: common questions
How much does a home energy audit cost in Thunder Bay?
Typical Ontario prices are about $500–$700 for the initial EnerGuide evaluation and $200–$450 for the follow-up, plus HST where it applies. Windfall Ecology Centre charges $500 + HST for the initial evaluation and $250 + HST for the follow-up, Reep Green Solutions charges $540 and $406 with no HST, and City-backed programs in Ottawa and London quote $500–$700 as typical for the first visit. Only assessments from the seven HRSP-approved organizations qualify for the $600 Home Renovation Savings rebate, and none of the seven publishes a price.
How many companies do EnerGuide evaluations in Thunder Bay?
NRCan's list of service organizations shows 8 licensed organizations with Thunder Bay postal codes (checked September 25, 2026). Four of the seven organizations approved for Home Renovation Savings assessments are among them, and only those seven qualify for its $600 rebate.
How long does an EnerGuide evaluation take?
The initial visit usually takes two to three hours, including the blower door test. The follow-up visit after upgrades is shorter.
Does an energy audit help with summer heat in Thunder Bay?
Yes. The advisor's upgrade list covers air sealing, attic insulation and windows, which slow summer heat gain as well as winter heat loss, and the evaluation's measurements are the starting point for sizing a heat pump that also cools.
Which rebates need an EnerGuide evaluation in Ontario?
Currently: Home Renovation Savings — Home Energy Assessment path (Up to $10,000 per home ($5,000 if heated with Enbridge gas), including $600 back on your two assessments, for insulation, windows, air sealing and more — if the follow-up assessment is done by December 31, 2026). Check the program page for current terms before you book.