Preliminary test results are in: 0.3 ach50

The big news is that we had a preliminary blower door test done this morning. All sorts of people from Cocoon, which is doing the insulation, and BKI (Building Knowledge) and TEC (The Energy Conservatory amd manufacturer of the blower door) came to watch the big show. They were not disappointed!

They sealed the blower door into a doorway and then turn on a calibrated fan to draw air out of the house, depressurizing it, so that any holes in the building envelope would allow air to infiltrate. They spent a fair amount of time setting up for it. We have temporary doors on at the moment, and some don't even have knobs, just holes for them, so they had to be sealed.

After they had everything set up, the actual test only took a few minutes. They were ready with an infrared device to check for leaks, but the leakage proved to be so small that they just packed up their things and were done. Rosemary, our architect, tells me that a tightly constructed house will have a blower door test result around 5 ach50 (air changes per hour at 50 pascals). Passive house standard is 0.6 ach50. Our preliminary (mid-construction) blower door test result was 0.3 ach50. This could vary slightly up or down on the final blower door test, once the air handling equipment is in, the permanent well-sealed doors and custom made door sills are installed, the windows are fully trimmed, and the interior stud wall is insulated and drywalled. Needless to say, we're super happy.

Good blower door test results also earn us LEED points in Energy and Atmosphere "3: Air Infiltration." In IECC climate zones 5-7 (we are in zone 6), the prerequisite is 5.0 ach50. For achieving 3.5 or 2.0 ach50, we can earn two or three LEED points, respectively. At 0.3 ach50, we are VERY well positioned for all three points!