Ok, we had what was supposed to be the second and LAST blower door test, but I am not happy with the result and I may have Dean Benton of Benton Green Energy come again after I have fixed some problems.
|Blower door reading on August 6, 2014|
You may recall that a blower door test helps determine how much air leakage you have through the building envelope. The test involves putting a fan in an outside door frame and depressurizing the home to accentuate the air leaks. The house is depressurized to a level of 50 pascals which is about equivalent to the force of a 20 mph wind on the home. There are 2 main values that you get from the test - one is directly from the manometer as shown above and one is calculated based on the volume of the house. This article, Blower Door Basics by Martin Holladay on Green Building Advisor (GBA) explains it much better than I ever could.
|Blower Door Set-up while we were at the rough-in stage.|
The number shown on the manometer above is called cfm50 or the amount of air that moves through the home at 50 pascals of pressure. The other number is ach50 or air changes per hour at 50 pascals.
Our previous reading was 98 cfm 50. The above reading is 235, but I think it leveled out at 220. In any case, the number has more than doubled - 2.4 times greater than the last blower door.
Well, I have some ideas.
What do you think about this dryer vent? Do you think that there is some leakage around this pipe?
|Dryer vent through the wall, not sealed around the vent pipe. This was installed AFTER the first blower door test.|
What about the vent cover for the kitchen fan? Do you think that those little plastic louvers seal out air?
|This flimsy plastic piece covers one of the fan vents. A similar cover was on the dryer vent.|
|Lunos e2 Heat Recovery Ventilator (HRV)|
For example, the space above the bathroom and the bedrooms is not really sealed off from the rest of the house. It is within the thermal envelope of the building. Do I count that? I think so, but I am not sure. I am going to post a questions on Green Building Advisor to get their advice.
|Area above the bathroom. You can see the Intello Plus smart vapor retarder from 475 High Performance Building Supply. The ceiling joists are insulated with dense pack cellulose. There will be a small door that fits in the opening. It does not set tightly to the frame, however. Is this within the thermal envelope?|
So, the big change from the rough-in stage to almost completion (I know, almost completed at 18 mos later - crazy ) is the vents. We taped cardboard over the area where the vents were during the first test, but I don't know if you tape over vent covers when you go for the final test. That's another question for the knowledgable people at GBA.
I'll let you know more later. Thank you for visiting here.