Pictured above is the apparatus for conducting a blower door test. An outside door is removed and this device is installed in the open frame. Fan speed is increased until a pressure differential, inside to outside, of 50 pascals is reached. Then the amount of airflow is measured. This is the amount of air that is leaking from the house. Knowing this number and the interior volume of the house, simple math will provide the number of Air Changes per Hour at 50 pascals (ACH50). Code for new construction mandates a maximum ACH50 of 3.0. Passive House certification requires 0.6. This morning we did an initial blower door test to determine if we had any major issues to address before drywalling. We measured 0.65 which is an excellent result considering that we have loosely fitted sheathing where our front door will go. I fully expect that we will hit the Passive House target when the house is finished.