What is Blower Door Testing?

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Conventional wisdom tells us that windows and doors are responsible for most air loss in a house, but conventional wisdom isn’t always wise.  In fact, the most significant source of air leaks is usually a network of hidden cracks, chases, and penetrations that add up to the equivalent of one or two open windows. 

A steady exchange of air is essential for indoor air quality – the accepted standard is one complete exchange every three hours – but that kind of excessive air loss means you’re wasting energy by heating air that will soon be outside your home. 

Blower door testing is the key to identifying these energy-wasting leaks.  Here’s how it works:

Blower Door Testing | Evergreen Home Performance | Maine

  • A frame with a flexible panel that holds a large calibrated fan is installed in an exterior doorway.
  • All other exterior doors and windows are closed, interior doors are opened, ashes in woodstoves and fireplaces are covered, and dampers are shut.
  • The calibrated fan is slowly turned up until the pressure difference between inside and outside reaches a specific target – generally 50 Pascals.
  • A manometer measures the airflow required to achieve this pressure difference and reports it as cfm50 (cubic feet per minute at 50 Pascals).  Since it takes more airflow to maintain the pressure difference in a leaky house, this measurement indicates the home’s airtightness.
  • Airflow and building volume are used to calculate ach50 (air changes per hour at 50 Pascals).  Since this metric has been normalized for building size, it can be compared to other houses and standards.  It also indicates how close a building is to the accepted standard of one complete air exchange every three hours.

Blower door testing gives homeowners and Energy Advisors a big picture understanding of air movement in a house.  Since the pressure difference exaggerates air leaks, the test also helps Advisors locate air leaks, especially when combined with infrared analysis.  A final blower-door test at the end of the project confirms the improvements.

Contact us today to learn more!

207-594-2244

Update 12/2018: Evergreen has completed Phase II of my house (insulating and installing air/moisture barrier on exterior walls, replacing old windows) and now that heating season is upon us, the difference is astonishing. The house is tight as a drum and so easy to keep warm. Worth every penny. Thank you all! Working with Evergreen was a positive experience from start (no charge energy audit) to finish (a MUCH more comfortable home). Brian Robinson spent a lot of time with me on the audit, explaining clearly what he was finding in my ca.

Rebekah W.

Rockport

In the final stages of selling our home, and with a closing date set, an inspection came across an unanticipated issue in our attic. We quickly called in contractors, but nobody was able to identify the source of the problem. Then we thought of Evergreen. Brian Robinson was on site the next morning and immediately identified the source (a faulty roofing job completed three years earlier which had effectively sealed up portions of the ridge vent and restricted air flow - not easily visible with a quick inspection).

Robin McIntosh

Camden

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

The Evergreen crew who installed insulation in my attic were fantastic! They were very professional, worked exceedingly hard, and they did an excellent job. They were very pleasant and friendly to be around. They cleaned up beautifully after each work day, and left my home in great shape on when they walked out the door for the last time. I can't believe they were able to accomplish all that they did with heat soaring into the 80s and 90s. It was pretty unbearable up there! They have my highest praise and my gratitude.

Cynthia F.

South Portland

I was very impressed by the professionalism of this company and the workers. Brian R. was very prompt in replying to my questions; the crew was meticulous in all parts of the work and attentive to the safety aspects concerning Covid; and Brian was extremely thorough in the final inspection. My attic is now snug and warm and I've noticed that the second floor is warmer as well.

Julia S.

Rockland

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

We had Evergreen Home Performance of Rockland come in to make our home more energy efficient, and what a TOP notch crew. Brian and his crew did an amazing job from start to finish. Very knowledgeable and professional. We would Definitely highly recommend this crew to anyone who is looking for energy efficiency in their home with a company that truly is an expert and knows how to do a quality job and truly cares about their customer.

Melissa S.

Owls Head

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

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

A thorough inspection of our (older) house and its energy needs. Competent and personable work crew.

Jacob Watson

Great company. Very professional and thorough. They take the time to explain everything and offer options to fit your budget. Wonderful experience from start to finish.

Bonnie Eustace

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

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

Evergreen has insulated two homes that we've owned now and both times we experienced exceptional service and craftsmanship. Our rep, Justin, went above and beyond answering questions and the installation team was attentive to every detail, including pulling out old poorly installed insulation and redoing a bathroom fan that wasn't up to current code. They also left the place spotless every day! Our home is already so much warmer this fall and we are looking forward to using less oil this winter.

Eva G.

Falmouth

Evergreen Home Performance shows its expertise from start to finish. Evergreen did three house projects in winter/spring/summer 2020 for me, attic insulation, crawl space under a porch insulation, and basement foam/vapor barrier. From my initial discussion with Bryan, I understood the reasons for choosing different types of insulation, the associated costs, and time estimates. Evergreen scheduled in advance, came when they said they would, and the crews were highly professional in their work and demeanor.

Iris S.

Portland

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