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!

Evergreen removed and replaced the insulation in my attic. They did a great job!, Crew was excellent, and the whole thing went smoothly, and the attic was NOT easy to get into or work in, so kudos to some hard work done well!

Joel A.

Portland

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

Really great experience from start to finish with Evergreen. They helped us prioritize what needed to be completed first, and has made a significant difference in our hearing costs already. Plus they were really friendly and considerate to work with!

Amy W.

Kennebunk

I was extremely pleased with the professionalism and quality of service that I received from the Evergreen team. I met Richard to discuss options for insulation. I knew immediately that I wanted to do business with them because he did not try to over-sell extra services that I did not need. Dave was the project manager. He was not only kind, but very respectful of my home. I would highly recommend this company.

Darlyann M

Bath

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

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

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

The Evergreen team was amazing from initial assessment and planning to the crew that came to complete the work. Our basement encapsulation is the best money we've spent on our house by far. The work was thorough and high quality. And what a wonderful group of people to work with. I highly recommend Evergreen!

Martha Bracy

We are thrilled with the job Evergreen did to transform our 213 year old home into a warm, draft-free, cozy space. The entire team led by Bruce was prompt, courteous, knowledgeable, and hard working. If Evergreen could transform our home in this way, we are sure they would make a comparable difference in YOUR home!

Jonathan M.

Bridgton

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

We had Evergreen come out to our tiny old (100+ year old) house to see what they would recommend for decreasing our carbon footprint, saving money, and increasing our comfort in the cold season. Richard and Bryan were great to work with, patiently answering our many questions and walking us through multiple options. We could only afford to tackle a few areas this year; we ended up replacing some windows and having them weatherize the entire house.

Alan M.

Falmouth

Led by Brian Robinson, the Evergreen Home Performance team just completed an insulation refit at my home. It was truly a great experience from start to finish, a period of time that was a fraction of the time that I originally anticipated due to the team's unbelievable work habits and professional knowledge of their tasks. As impressive were the communication skills and friendliness of each and every member of the team.

Anne W.

Rockport

Professional, friendly and hard-working staff. The product/approach they use for insulation is top notch. We felt the difference immediately, both from added warmth and eliminating drafts. The team and management were easily available to answer our questions or coordinate meeting times. Highly recommended.

Kevin J.

Yarmouth

Thanks Evergreen Home Performance for helping to make our home more efficient. Many thanks as well to Bryan for the initial walk through and recommendations to make our home more efficient and to Dave, Roland, and Jacob for a job that was done professionally and courteous.  We were amazed at the level of efficiency and everyday they made sure to protect our floors, carpets, and furniture. We had daily discussions with Dave about progress and what was being done and where they were at in the project.

Carol Fink

I waited a year to write this review. Evergreen finished our job late last winter. Terrific results!!! we've gone from 12-day propane deliveries to 30+ day propane deliveries. The house is noticeably warmer. The Evergreen crew was/is professional, prompt, thorough, scientific, gracious and immaculate with respect to keeping our house clean. Money well spent.

John E.

Boothbay

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