What does a blower door test measure in a New Brunswick home? | Insulation IQ?

A blower door test is a diagnostic tool used during a home energy audit to measure the air leakage rate of your home's building envelope. During the test, a certified energy advisor mounts a calibrated fan and frame system in an exterior doorway — usually the front door — seals the opening around it, and then depressurizes the home to a standardized pressure of 50 Pascals below outdoor air pressure. By measuring how much airflow the fan must maintain to hold that pressure difference, the auditor can calculate exactly how leaky your home is.

The result is expressed in several ways, but the most commonly referenced metric is ACH50 — air changes per hour at 50 Pascals. This tells you how many times per hour the entire volume of air inside your home would be replaced if the pressure difference were maintained continuously. In New Brunswick, older homes typically test at 10 to 15 ACH50 or higher. A well-sealed modern home in Climate Zone 6 should target 3.0 ACH50 or below, and high-performance builds aim for under 1.5 ACH50. The current NB Building Code requires new construction to meet a maximum of 3.0 ACH50 confirmed by blower door testing.

What makes the blower door test particularly valuable is what happens alongside the measurement. While the home is under pressure, the energy advisor uses infrared thermography (thermal imaging camera) and smoke pencils to identify exactly where air is infiltrating. In New Brunswick homes, the most common leakage points include attic hatch perimeters, electrical outlets and pot lights on exterior walls, basement rim joists, plumbing and wiring penetrations, and gaps around window and door frames. In Saint John's older housing stock and Moncton's post-war bungalows, it is common to find significant air movement through interior partition walls that connect to unconditioned attic spaces.

Air leakage is not the same as insulation deficiency, but the two are closely related. A well-insulated wall with air gaps still loses heat rapidly because convection carries warm air through and past the insulation. This is why air sealing and insulation improvements are nearly always recommended together. In Climate Zone 6, uncontrolled air infiltration can account for 25 to 40 percent of a home's space heating energy consumption — a substantial fraction given New Brunswick's long, cold heating seasons.

The blower door test result is also required to establish your home's EnerGuide rating, which is the official energy efficiency score used to calculate Canada Greener Homes Grant eligibility and NB Power rebate amounts. Without the blower door component, the audit cannot generate a valid EnerGuide label. The test is performed both before and after any retrofit work; the post-upgrade blower door result confirms improvement and is needed to claim rebates.

For homeowners, the practical implication is straightforward: air sealing is often the highest-return investment you can make before adding more insulation. Adding R-20 batt insulation to a leaky attic helps, but not nearly as much as first sealing the bypasses and then insulating. Certified energy advisors serving Fredericton, Moncton, Miramichi, and the rest of New Brunswick will walk you through the blower door findings and prioritize which sealing work to tackle first.

If you are considering insulation upgrades and want to understand your home's air leakage profile first, the New Brunswick Insulation directory and the New Brunswick Construction Network can connect you with qualified energy advisors and insulation professionals who understand the full audit-to-upgrade process.

---

Looking for experienced contractors? The New Brunswick Construction Network connects homeowners with qualified professionals:

• moose luxury painting
• Thirty Four Renovations
• 3Tone Construction Ltd
• Gionetterenovations
• Brunswick insulation & roofing