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

Back to Blog

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?

Learn where those leaks are and seal them up for good!

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

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

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

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

Our house still the most efficient home we’ve ever lived in. And we have you folks to thank for that! A special howdy to Brian Robinson please!

Bruce O’Donal and Eva Butler

First we have Evergreen do a BIG project worth about $20K (windows, basement, insulate & rebuild an entire wall, a door, attics, and air sealing). They were so great we had them come back later when we decided we did want to do our other door. They are professional and do great work. They take care of your home and are trustworthy, and on top of all that friendly! I highly recommend you call them!

Garreth C Debiegun

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

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

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

Several years ago Brian Robinson evaluated the crawl space at my summer home on Islesboro where I knew moisture was becoming a problem. I had done quite a bit of work in the space many years prior with mixed results. When Brian offered some suggestions, they were ideas that incorporated work previously done, and would be a relatively low cost effort to improve the situation. He offered this advice over several phone conversations of some length, informally, and at no charge.

Cliff R.

Islesboro

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

Bryan, Dave and the entire Evergreen team are wonderfully professional, prompt and thorough. I enjoyed working with them and look forward to continued work as we upgrade our home! Thank you so much for your professionalism, fairness, time and diligence.

Cait

Yarmouth

We had Evergreen redo the insulation in our roof. The team handling our project did a great job. They left the house spotless. We've already noticed the difference in how much better our house is retaining heat. I would definitely recommend and will use them for future projects.

Ffej C.

South Portland

Great team!

George S.

Bath

I have always been impressed by the high level of service, quality of work, and excellent follow-through provided by Evergreen Home Performance in the three projects that they completed at the Wells Reserve at Laudholm over the past several years.

Paul D.

Wells

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