What does the blower door test tell you about your home?

Have you ever seen a photo of a blocked off door with a fan spinning and wondered what that’s for? It’s called a blower door test, and it’s a key part of the Home Energy Assessment process. Let’s find out why.

What’s the purpose of the blower door test?

While you might feel drafts around your house, the blower door test tells us exactly how much air is leaking out of your home. Two common problems we look for with this test are:

The home leaks too much air: In winter, the hot air you’re paying to generate can easily leak out through cracks which affects home comfort and costs you money.

The home is too airtight: While an extremely airtight home will trap heat effectively, it will also trap moisture if it’s not ventilated correctly which leads to condensation, mold and mildew problems.  

How does the test work?

1. A Home Energy Advisor closes all windows and doors and sets up a large fan in one of your exterior doors.
2. When the fan is turned on, it sucks all air out of the house, depressurising it.
3. While the fan is running, the Home Energy Advisor can physically feel where air is trying to get into the house and show you some examples.
4. The pressure gauge on the equipment measures the air leakage of the home, which the Home Energy Advisor records and can use to make recommendations.

What happens next?

After reviewing the results, the Home Energy Advisor can make recommendations depending on what is best for your home. Some common upgrades included in Clean Energy Financing that can help with air sealing are:

• Insulating a basement with spray foam.
• Blowing insulation into empty wall cavities.
• Blowing insulation into an attic, particularly if that includes refurbishing a hatch and sealing light fittings.
• Replacing windows and doors.

Once your upgrades have been installed, your Home Energy Advisor will repeat the blower door test in their follow up audit. This tells us if there’s been any changes to the airflow in your home with the upgrades and can help assess if they’ve been installed correctly.