Blower door testing in Nanaimo

Nanaimo gets about 2,939 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 −3.2°C. Those figures come from the climate data for Comox, the closest comparable location in that data set (87 km away) in HOT2000, the home-energy software Natural Resources Canada (NRCan) gives energy advisors. That's about 25% less heating demand than the middle of the 70 cities we cover. Mild, wet winters: heating bills are modest, so moisture control and comfort matter as much as cutting heat loss.

Leaks also let damp air into walls and attics, so the coast's wet winters are a reason to find them before adding insulation. Nanaimo 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. Wildfire smoke reaches Nanaimo in some summers. The Government of Canada's advice is to keep windows and doors closed, limit exhaust fans and use the best filter your system can handle, so ask the advisor what your furnace or HRV can take.

Of Nanaimo's 33,520 houses (single-detached, semi-detached, row houses and duplexes), 15% were built before 1961 and 54% 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.

• Radon. Sealing shifts the pressure balance between the house and the soil. Health Canada's 2012 survey found 0.9% of 109 homes tested in the Central Vancouver Island Health Service Delivery Area health region above the guideline. The larger 2024 Cross-Canada survey reports 1.3% (1 in 75) of households at or above the guideline for Pacific Coastal Canada (Vancouver Island, Sea-to-Sky, Sunshine Coast, northern BC coast, Lower Mainland and western Fraser Valley up to but not including Chilliwack). Test before and after big air-sealing jobs. Radon testing in Nanaimo

A blower door test is part of every EnerGuide evaluation rather than a separate purchase. There's no provincial price list; the City of Nanaimo quotes $400–$500 as typical for an existing home. Several B.C. municipalities subsidize evaluations for their residents (see local programs below).

• 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.