How Thunder Bay is built
- Before 1961 43%
- 1961–1990 41%
- 1991–2000 7%
- 2001 or later 9%
Why air leakage matters in Thunder Bay
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.
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. Older houses usually test leakier than newer ones, and an EnerGuide report compares your result with homes of the same era, so you can see whether your house is typical or a problem.
After you seal: two checks
- Combustion safety. In the Thunder Bay area, the main heating energy is natural gas for 81% of households. A tighter house changes how fuel-burning appliances vent, so the spillage check should be repeated after serious air sealing. Combustion safety testing in Thunder Bay
- Radon. Sealing shifts the pressure balance between the house and the soil. Health Canada's 2012 survey found 12% of 108 homes tested in the Thunder Bay District Health Unit health region above the guideline. The larger 2024 Cross-Canada survey reports 34.3% (1 in 3) of houses at or above the guideline for the Thunder Bay, ON (Thunder Bay CMA) metro area. Test before and after big air-sealing jobs. Radon testing in Thunder Bay
What it costs in Thunder Bay
A blower door test is part of every EnerGuide evaluation rather than a separate purchase. 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 the test works
- A calibrated fan is fitted into an exterior door and pulls air out until the house is at 50 pascals, the standard test pressure.
- The result is air changes per hour at 50 Pa (ACH50): how many times an hour the whole volume of air would leak out and be replaced at that pressure.
- While the fan runs, you and the advisor walk the house and feel for leaks at the attic hatch, rim joists, pot lights, trim and plumbing and wiring penetrations.
- A second test after the work shows what changed, and it is what most rebates pay on.
Very Cold East Northern Ontario, Saguenay, Quebec City
What this means in Thunder Bay’s climate
Deep, snowy winters: stop ice dams, and pair a cold-climate heat pump with backup heat.
Why it matters here: Finds the attic and rim joist leaks that feed ice dams.
Best timing: Any season; most useful with a thermal scan in winter.
- 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. Ask: Ask the advisor to trace attic bypasses with the blower door and thermal camera, and to check insulation depth.
- 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. Ask: Ask whether the basement is dry enough to insulate from inside, and how much the rim joist leaks.
What else 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. A blower door test is part of every EnerGuide evaluation, so any organization below can do one in Thunder Bay. Ask to walk the house with the advisor while the fan runs.
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
Programs that include a blower door test in Thunder Bay
Blower door test in Thunder Bay: common questions
Where can I get a blower door test in Thunder Bay?
Book an EnerGuide evaluation with any of the 8 NRCan-licensed organizations serving Thunder Bay; the blower door test is part of every evaluation.
How much does a blower door test cost in Thunder Bay?
It is included in an EnerGuide evaluation. 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.
What is a good blower door result?
Lower is better. Your EnerGuide report compares your air changes per hour at 50 Pa with homes of the same era, which is more useful than a single target number.
Does air sealing affect radon?
It can. Tightening a house changes the pressure difference with the soil, so test for radon before and after major air sealing.