How a Blower Door Test Can Help Improve Your Home Comfort and Indoor Air Quality

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Has your older Maine home been a bit drafty lately, or have you noticed an increase in dust throughout your home? Or maybe you’ve realized that your new home is costing you more than you estimated for utility costs, and your heating and cooling equipment are struggling to keep you comfortable. These are all signs that your Maine home is full of air leaks. 

Regardless of what is causing you to take notice of the air leaks in your home, you probably want to resolve the issue, and residential air leakage testing can be a great help. Blower door tests are the industry standard when it comes to whole-house air leakage tests, and they’re used to resolve home air leakage rates that are too high for optimum comfort and efficiency. Here is what you need to know about how they work and how you can benefit.

What Is a Blower Door Test and How Does it Work?

The blower door test was invented in Sweden in the ’70s and had shown up in American homes by 1979. The goal of a blower door test is to provide a reading of the total air leakage throughout a building, and this is done by attaching a large fan to an exterior door with a special pressure gauge device attached. 

A blower door is temporarily attached to a home using an airtight skirt made of a plastic material, then all other exterior doors and windows must be shut, while interior doors remain open. Once the set-up is complete, your blower door technician will turn the fan on to create a negative pressure inside the home (the fan blows the air out, not in). 

After a few adjustments to complete the pressure gauge readings, the blower door test is complete and your blower door technician will be able to assist you in understanding the findings!

Understanding Blower Door Test Measurements

When a blower door fan creates a negative pressure within your home, outside air is pulled into your living space through whatever pathways it can find. With all of your outside windows and doors shut, this only leaves tiny, hard-to-reach, and often invisible air leaks for outside air to travel through. At this point, the pressure gauge is measuring:

  • If your home is airtight enough to reach 50 pascals

  • How many times the air in your home is replaced with outside air (Air Changes per Hour, or ACH)

  • The resulting air leakage in Cubic Feet per Minute (CFM)

  • How much air infiltrates your home naturally, without the blower door

These measurements are used to understand how air moves freely into and out of your home. So, how can an experienced home performance contractor like Evergreen Home Performance use the results of your blower door test?

What Happens Next?

A blower door test is all a part of a greater home diagnostic service, called an energy audit, and the data is used to select the measures needed to increase the overall comfort and efficiency of your living space. Your Evergreen Home Performance Energy Advisor can utilize infrared thermal imaging during the test to help locate the air leakage locations. Then, when your Evergreen technician crew arrives to air seal, they seal them up until your home is as airtight as possible. This is called air sealing

Air sealing provides you with greater control over your indoor temperatures, and the blower door test data helps determine how much ventilation your home needs to keep it safe and healthy. Usually, existing home ventilation equipment (like range hoods and bathroom fans) can be optimized to do the job.

What’s more, the same infrared imaging can be used to locate areas of poor insulation. Replacing outdated or damaged insulation can increase the overall effectiveness of your home improvement project, and should be completed alongside air sealing. 

With proper air sealing  and insulation, your Maine home will be:

  • More comfortable

  • Healthier to live in

  • Less expensive to heat and cool 

  • Less drafty

Want to keep Maine’s unpredictable outside air away from your comfortable and healthy home? Schedule an energy consult with Evergreen at or get in touch here.

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The team members were very professional, worked very hard, paid very close attention to detail and cleaned up meticulously every day. I really appreciated the care they took knowing the smallest details were going to make a big difference to our heating bills. Thank you!

Pam B.

Brunswick

We had Evergreen energy do blow-in cellulose. I was very happy with the result. They tested with blower-door before and after. House is now MUCH warmer. Also, in the time since when I've had to open walls for various access, I've been impressed with how they got the insulation packed in everywhere. I'd use them again.

Noah

Peaks Island

The folks at Evergreen did a great job fixing a rather major insulation problem in my house, which they helped identify with a great audit. When the work began, they were thorough, upbeat, and -- dare I say it -- efficient. I strongly recommend them.

Michael Williams

Last week, my oil company asked if we were using some other kind of fuel because our usage was so much less than they had expected We are very happy with the results; the house is much more comfortable

Steve T.

St. George

Working with Brian and with Nate and the rest of the crew was a pleasure. They made everything very easy and understandable. This was a major renovation and they were always at the ready with a lot of information. We had an extensive renovation on the basement which was a dirt basement and it came out beautifully. We can already tell from all of the insulation work what a difference it's made in sound and temperature. Brian worked with me on the rebates that are available when you do this kind of work. I would highly recommend this company to…

Valerie L.

Rockland

Our basement was the eyesore of the house. I wanted to make improvements, but first needed to make structural, insulating and moisture mitigation improvements. Evergreen was professional and competent in taking on a complex project of not only encapsulation and insulation of basement and crawlspace, but completed needed improvements to the structural integrity of the wood floor platform above a crawlspace and brought in a concrete contractor to pour where there was once a rotting, tiered wood platform - replacing that area with a more functional and tight tiered concrete area.

Duane B.

East Boothbay

Evergreen did everything they said they would and more. I actually don't mind going into the basement now since they sealed it. The air quality in the house is noticeably better and it's warmer in the winter. We can even store clothing down there where before, whatever was in there would mildew. Even the spider population declined! I used to vacuum so many of them from the corners of the ceilings in the house. Not any more!

Loriel Van Dusen

Evergreen is a terrific company to deal with. Polite and efficient crews, meeting deadlines and major reduction in our heat bills. They corrected a lot of issues we suffered from doing work with a shoddy building contractor. We would recommend them to anyone.

Mary Carey

Awesome company. It was a few years ago that they did the audit and then we commissioned them to do the work. We subsequently sold our house and moved to South Africa, but their level of service and expertise will live on.

Odette Brown

I am very pleased with my experience with Evergreen Home Performance. I met several times with Richard Burbank and he was very detailed in his explanations to all of my questions. He provided me with several options for improving the insulation to our home. The team of installers were very professional and respectful of our home. They did a great job of cleaning up every day after the days work and they were also very responsive to all my questions as well as we collaborated to get our home better insulated. It was a pleasure to work with Richard and…

Brian C.

Falmouth

Evergreen listened and produced a thoughtful evaluation, proposal and comprehensive plan for our attic and basement. They exhibited excellent workmanship, teamwork, and came back as planned after the completion of the job to test the outcomes. Their overall performance as insulation and home improvement contractors is truly outstanding and we highly recommend them.

Susan S.

Saco

Evergreen has a professional and reliable team of people who do excellent work. If you want the best of the best in the area, select Evergreen to accomplish your insulation needs.

Mary E.

St. George

Very easy process, start to finish.  Friendly, professional, and really know their stuff.  They made some improvements to our condo and we were very happy with how it played out.  Would definitely recommend them.

Clayton Eames

The Evergreen Team did a fabulous job, well exceeding our expectations, In just over a week they transformed our very drafty, noisy 213 year old house into a snug, draft-free, quiet haven with warm floors! The team was prompt, did everything they said they'd do and more. We are thrilled!

Trudy M.

Bridgton

Greetings one and all! I am writing to express my gratitude to all involved in my insulation project.  From start to finish, I appreciate the universal theme which was maintained by each and every one of you, to ensure that my home was insulated and protected from freezing pipes as if it was your home. Andrea, thanks for helping me navigate my way to the project. Nate, thanks for the thorough initial assessment and the time you took to explain this project to me, step by step. Brian, thanks for setting up my project - so happy

Michele

Portland Buy Local
Efficiency Maine
EPA Lead-Safe Certified
Building Performance Association
BPI Certified