The TerraHaus passed its initial Passive House blower door test today! A blower door depressurizes a building and measures the rate of air leakage into the building at a standard test pressure of 50 Pascals. Whereas we might expect a building this size to have 10 air changes per hour (ACH) at this pressure, the TerraHaus has met the standard at less than 0.6 ACH.
How much is 50 Pascals? It simulates a 20 mile per hour wind blowing directly on on all sides of the house simultaneously. To convert this to natural air changes per hour energy auditors would divide this by about 20 in wind-protected sites or 15 for exposed homes in Maine.
For certification, G O Logic will submit the results of a final blower door test when construction is completed and details such as insulation levels, solar heat gain, and thermal bridging to the Passive House Institute of the US (PHIUS). PHIUS uses a sophisticated modeling program known as the PHPP to calculate the building’s energy requirement to maintain a 70 degree F temperature.
The successful blower door test is huge hurdle to overcome on the way to certification. It is a testament to both design (kudos to Alan Gibson and Matt O’Malia of G O Logic) and craftsmanship (kudos to the G O Logic construction crew). Congratulations to all involved on this milestone!
Stats: CFM50 = 132 ACH50 = 0.53