The Potwine Passivhaus Gets Insulation and Drywall
After plugging everything up, we got a final flow measurement, in units of cubic feet per minute (cfm). The certification guy (Mark Newey, of CET) then calculated the number of air changes per hour, meaning the fraction of air that would leak out of the house during an hour, arriving at 0.23 ach at 50 Pascals, an unbelievably awesome number! The Passivhaus target is 0.6 ach50, and almost nobody gets down near 0.2 ach50. We high-fived each other and went home. Only later, when I relayed the information to the architect, did we realize that we were using the wrong number for the volume of the home. In reality, the result came to 0.34 ach50 — still an excellent number and a huge testament to the amazing craftsmanship of Don the carpenter and the rest of the Integrity team.