Blower door testing in Cambridge

Cambridge gets about 3,664 heating degree-days a year and has a winter design temperature of −18.3°C, according to NRCan's HOT2000 climate data for Toronto International, the closest comparable location in that data set (63 km away). That's about 7% less heating demand than the middle of the 70 cities we cover.

Of Cambridge's 41,030 houses (single-detached, semi-detached, row houses and duplexes), 23% were built before 1961 and 60% 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.

• Combustion safety. In the Kitchener-Cambridge-Waterloo area, the main heating energy is natural gas for 64% 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 Cambridge
• Radon. Sealing shifts the pressure balance between the house and the soil. Health Canada's 2012 survey found 4% of 101 homes tested in the Waterloo Health Unit health region above the guideline. The larger 2024 Cross-Canada survey reports 10.2% (1 in 10) of houses at or above the guideline for the Kitchener-Cambridge, ON (Kitchener-Cambridge-Waterloo CMA) metro area. Test before and after big air-sealing jobs. Radon testing in Cambridge

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.

• 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.

The blower door test in detail.