Disappointing Blower Door Test

Since working with the Metro Green Homes Tour I have met several people who have been active in sustainable and energy efficient housing for years. One of these new friends offered to come over with her equipment and do a blower door test.
We had a test in 2012 when we first started the remodel. Although not terrible it was 3250 cfm at 50 pascals, the typical blower door pressurization that sucks air from the house. At that pressurization the number of cfm that are pulled through the house measured by the air pressure device is used to determine the air tightness of the house. The motto is build it tight ventilate right.
Nancy K. set up her equipment to do the test. First a metal frame was assembled. It had latches to slide the pieces up and down and to the correct width for my door.

Blower door frame
Blower door frame

Then a nylon cover was draped over the frame and Velcro’d on.

Frame cover
Frame cover

The cover’s frame was set into the door and stretched to fit tightly then clamped in place. The large barrel fan was inserted into the circular opening and the tubing was connected to make the readings with the air meter.

Frame positioned in door
Frame positioned in door

When the meter reached 50 pascals of air pressure the reading of cfm passing through the fan was measured. The reading pulled air from within the house at a steady rate of about 2700 cfm.

Waiting for 50 pascal air measure
Waiting for 50 pascal air measure

Given that I had worked pretty hard to seal up the remodeled part of the house I was shocked that the cfm reading at 50 pascals was 2700 cfm. That’s only about a 17% improvement. New windows and doors and new insulation in the walls and ceiling with expensive air barrier membrane inside would expect a bigger gain in air tightness.
We went around the house looking for spiderwebs moving in the corners. We also felt for air intrusion. It turned out there is lots of air intrusion from the rooms I have not done. The most came from the foundation areas around the new windows and the rear of the utility room wherever pipes pierce the outer wall. And the garage door actually whistled as air came rushing in all around it.

Nancy could see how disappointed I was. Oh my, all the work done and money spent on our main living space only to be losing so much air through the older part of the house!
I fretted about it for a day then started making plans to seal up the rear of the house. No excuses. It has to be done. now that I have a friend with a blower door though I can improve and get another test before the LEED evaluation.

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