What does a New Brunswick blower door test show?

A blower door test measures exactly how much air is leaking through your home's building envelope — and where those leaks are located. It is the single most important diagnostic tool for understanding your home's energy performance, and it is a required step for both NB Power and Canada Greener Homes Grant rebate eligibility.

How the Test Works

A certified energy advisor temporarily installs a calibrated fan in an exterior doorframe — usually the front door — and seals the opening around it with a flexible panel. The fan depressurizes the house to a standard pressure of 50 pascals, which is roughly equivalent to a 20 km/h wind blowing on all sides of the house simultaneously. At that pressure, the equipment measures how much air is flowing through the fan to maintain the pressure difference, which equals how much air is leaking in through every crack, gap, and penetration in the building envelope.

The result is expressed as ACH50 — air changes per hour at 50 pascals. This number tells you how many times per hour the entire air volume of your home leaks out and is replaced when the building is under that standard pressure. The NB Building Code requires new construction to achieve 3.5 ACH50 or better. Passive House standard targets 0.6 ACH50. Most older NB homes — particularly the 1960s through 1980s construction that makes up a large portion of the housing stock in Moncton, Saint John, and Fredericton — test between 8 and 15 ACH50, meaning the house is leaking like a sieve.

What the Numbers Actually Mean for Your Heating Bill

At 8-12 ACH50, a typical NB home is losing a significant portion of its heat not through the walls or attic, but through air leakage — gaps around pot light housings, plumbing stacks, electrical penetrations, attic hatches, rim joists, and the countless small openings that accumulate in a house over decades. In NB's climate with 4,800 to 5,200 heating degree days per year, that air leakage translates directly into hundreds or thousands of dollars in unnecessary heating costs annually.

The blower door test also guides the air sealing work itself. While the fan is running and the house is depressurized, the energy advisor or contractor can walk through the house with a smoke pencil or thermal camera and feel or see exactly where air is entering. This turns a guessing game into a precise diagnostic — you know which attic penetrations to seal, whether the rim joist is the biggest problem, and whether the basement sill plate is leaking.

Why This Matters Before and After Insulation

Getting a blower door test before insulation work identifies where air sealing effort will have the greatest impact. Air sealing and insulation work together as a system — adding R-60 of blown-in cellulose to an attic with unsealed pot light housings and plumbing stacks wastes 30-50% of the insulation's potential benefit because conditioned air still escapes through those gaps. The test tells you what to fix first.

Getting a blower door test after the work verifies that the air sealing was actually effective and documents the improvement for rebate purposes. NB Power's Total Home Energy Savings Program and the Canada Greener Homes Grant both require pre- and post-retrofit EnerGuide evaluations — which include blower door testing — to qualify for rebates. If you skip the pre-retrofit test, you lose eligibility for up to $10,000 in combined provincial and federal incentives. This is the most expensive mistake NB homeowners make when planning insulation upgrades.

A blower door test typically costs $300 to $500 as part of a full EnerGuide evaluation by a certified energy advisor. Given that it unlocks thousands in rebates and tells you exactly where to spend your insulation budget for maximum return, it is one of the highest-value investments you can make before starting any retrofit project.

New Brunswick Insulation can connect you with local professionals who work alongside certified energy advisors to plan and execute insulation upgrades properly. Browse insulation contractors in your area through the New Brunswick Construction Network directory at newbrunswickconstructionnetwork.com/directory?category=insulation.