Air sealing did not improve blower door test results. Why?
halaby
| Posted in Energy Efficiency and Durability on
I recently air sealed and insulated my house as follows:
1) air sealed 40 recessed cans;
2) air sealed all major attic penetrations;
3) spray foamed all my basement and crawlspace sills;
4) topped up all the attic insulation to 50R
The blower door test results were the same on post-test and pre-test. How does that happen?
Alternative retest methods did not change this outcome — no improvement detected. The energy auditor could not explain it.
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Replies
Charles,
Here are some possible explanations:
1. The blower door tests weren't performed correctly, and their results are inaccurate.
2. Your air-sealing efforts were sloppy.
3. Your air-sealing efforts were excellent, but there is a monstrous hole in your thermal envelope that you have not yet located.
Charles,
First, your # 4 doesn't necessarily help with air sealing.
Also, similar to what Martin said with his #3: It sounds like your leakage is in places different from those you sealed. As surely you know, there are many other places for infiltration than those you mentioned.
There is no substitute for blower door-guided air sealing. You run the fan the whole time, either pressurizing or depressurizing, find the leaks, seal them, and confirm as you go that the manometer shows a reduction. I have done pre and posts tests for crews that did not do this, and they often don't get much improvement. For that matter, I don't do much without the fan running myself.