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.

Is your home drafty and full of air leaks?

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We needed basement encapsulation to stop moisture coming up into the house from our regularly flooding basement. We had mold growing on windowsills and furniture. All the staff were friendly, respectful of our home, and easy to work with. Humidity has gone from 70% down to 40% and mold has not grown back after two months. Very grateful.

Sarah C.

Belfast

We just finished a large project of air sealing and reinsulating our 1890s basement and attic which had been completely renovated 8 years ago but still felt cold and lacked proper energy assessment and corrections. We met with Justin in December and were very impressed with his knowledge, professionalism and communication skills and knew Evergreen was who we wanted to work with. Dave was our on hands project manager and was excellent. The office staff has been quick to respond and helpful as well when needed.

Emily Gallant

I highly recommend Evergreen! 1st, I had a home efficiency inspection (that was free) & Bryan P. was great! He took the time needed, asked & listened to what I thought were priorities, explained clearly what he thought were priorities & why, then gave me numerous options. No pressure whatsoever. Then I had my attic sealed & insulated as the 1st step & Bryan came along on day 1 to introduce everyone & make sure we were all on the same page. Bruce's team (inc. Kelsey & Roland) did the work - they were exceptional!!

Melissa M.

Kennebunk

My experience with Evergreen was excellent. From their thorough and thoughtful initial consultation to their detailed post-work visit, the team was professional, knowledgeable, and responsive. Their workmanship was top notch. Our home is now much warmer and more efficient. I highly recommend their services!

Douglas R.

Edgecomb

Evergreen came out 2 years ago to do an assessment and insulate our roof. This year we had them come back and do the basement as well. They are hands-down the best crew we've ever hired to work on our house. They are experts at what they do, and super meticulous in their work. After working in our house for a week with blown insulation, there was no trace they were ever here. We've seen a huge decrease in our energy bills while at the same time the house has become way more comfortable. Can't recommend them enough.

RC Lations II

Portland

We are so pleased with the work the team from Evergreen Home Performance did in our home. The project included encapsulation of our basement with a reinforced vapor barrier, installation of a sump pump, spray foam insulation on the walls and insulation of the heating duct work. Everyone at Evergreen was friendly and professional. The project was completed on time and in budget. Our home is much cozier and warmer since the project was completed.

Linda Metzger

I had gotten estimates from several other companies, but Evergreen was in another league entirely with their professionalism. If you want the job done correctly, I couldn't recommend this company enough.

Rayna Mayo

Freeport

Great job installing windows and insulation.

Bob S.

Rockland

Evergreen has just completed Phase 2 of 2 at my home. They are professional, hard-working and courteous. They communicate well..no surprises. They've gone above and beyond to make my home comfortable and were very respectful of my home.I recommend them unequivocally!!!Many thanks to Brian, Brian, Rick, Eddie, Dawson and the rest of the Evergreen crew!!

David Henry Feldman

They were highly recommended. I found them to be very knowledgeable and so helpful, with practical ideas. Despite my not living within their service area, they were generous with their knowledge, describing the usual solutions to correct leaks in my basement, and what the result is likely to be by following path A, B or C, and why. I was discouraged. Talking with Evergreen helped me see that my basement problems are far from insurmountable and really, fairly common in 100-year old homes. There are proven solutions.

Rosalind J

Damariscotta

My husband and I bought a home on the water in Owls Head and decided to make the investment in Evergreen's recommendations for insulation. Brian Robinson spent 3 hours examining every nook and cranny before he made practical suggestions and explained them thoroughly to us.

Marie McNeely

Owls Head

Thorough, smart, informative, integrated, and communicative -- that's how my experience was with Evergreen even with the covid interruption midstream. The team picked up where they left off, insulated basement and air sealed attic and knee wall in 100' temps under the eaves! This business group was a pleasure to work with.

Karen W.

Gray

I would recommend Evergreen wholeheartedly because of their professionalism, their follow through, and thoughtful project planning.

Jennifer A

Evergreen is the "go-to" company for improving the efficiency of your home. There are others to choose from but none so effective, honest, and capable as Evergreen. They did a great quantity of dense packing cellulose to improve our home (both for energy efficiency and for sound insulation) and it was totally successful. They are on-time, helpful, and caring. They clean up to a level that can't be over emphasized. This was the second time we employed them and we'd use them again if the opportunity came. You'll not be sorry to select Evergreen.

Dirk F.

Belfast

From beginning to end – that is from the moment Justin McEdward stepped into our home to assess our energy conservation needs until the crew left – the Evergreen Home Performance process went absolutely smoothly. Justin made a thorough inspection and took pictures with an infrared camera. His proposal described the scope of work in detail, and he explained what we could expect the proposed work to accomplish. Our proposal was forthcoming within a couple of days, and Justin was available to discuss it and answer questions.

Adrienne Harkavy

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