April 28, 2009

Huffed and they Puffed.....

After months of insulation working through one of the worst winters in memory, we come to where the butter hits the toast. Sort of. We are performing the blower door test to see how tightly the house has become.

Larry Masland arrived from the Department of Energy Resources, Gary and David arrives from Synergy Construction, Kohto arrived from Building Science Corporation, plus two guys from Conservation Services Group which will be performing the blower door test.

For the blower door testing, we closed all windows and doors, put these lovely red frocks on the back doors, engaged the fans inserted within said frocks, and started sucking the air out of the house to reduce the internal pressure. For those of you concerned about such things, the fan was not of a power to make us gasp for air, boil our blood, bulge our eyes, or make us float around the room.......which would be more of a gravitional problem.....ANYWAYYYYYY

Here's what the test looked like.

How'd we do?
Here are the results.

The results are not official, but the house is around 60% - 65% tighter. The walls and the roof were not really serviceable. They were as tight as they were ever going to be. But air still flowed into the basement, and therefore somehow up into the house through the basement ceiling. With the fan drawing, with some smoke pens, with a few cans of insulation foam, we should be able to walk around the basement, and then track and kill each tiny ceiling leak. But this was not to be, as everyone's schedule would not permit. Big disappointment.

UPDATE: To answer the comment from Jerry Marin: "So what was the cfm? Enquiring minds want to know."
With the basement door open the leakage was 2825 CFMs (cubic feet per minute)
With the basement door closed the leakage was 2275 CFMs
(Explanation: These leakage rates are during a highly de-pressured test, not during normal usage.) The original pre-project leakage rate in August was 7800 CFM (more or less until I track down the exact test result).
The team was very pleased with the results, but I know that we can do better. I am confident that with 60 minutes we could bring that result south of 2000 CFMs. The disappointment here is that the basement ceiling is completely at hand and reachable. I will attempt to get some sort of de-pressurization using the building's 2 kitchen fans and 3 bathroom fans, get some incense "punks" (are they called "punks" anymore?), armed with a can of foam. Only problem is that we will never have a new reading of the results.


Jeremy Marin said...
This comment has been removed by the author.
Jeremy Marin said...

So what was the cfm? Enquiring minds want to know.

Romain said...

To Jeremy Marin:

CFM means cubic feet per minute. This unit of measurement is used to gauge the air leakage of a house. On this project the original (pre-project) blower door number was 7800 CFM. This is the airflow needed to create a change in building pressure at 50 Pascals - the industry standard. This project final blower door test was around 2300 CFM; this is a dramatic drop. No wonder the project coordinators are pleased. The house is now very tight.
Another factor to take into account is the Building Tightness Limit. It is typically around 1300 CFM depending on the size and exposure of the building. You don't want your weatherization work to bring the building's air tightness to this level or below.

I have useful guides and articles if you are interested at my website:


Feel free to email me with any questions; Romain@americanbuildingtechnologies.com