The FireWise, Zero-Net-Energy rebuild that is underway out side of Fort Collins, CO just conducted the preliminary blower door test.  It achieved an incredibly tight 0.15 ACH50 (Air changes per hour at 50 pascals pressure).  This is more than 20 times more airtight than a typical code-built home and 4 times more airtight than the stringent standard for which we were aiming in order to achieve Passive House certification.  Achieving this level of air-tightness is the result of careful design, phasing, and construction quality.  The next step will be to conduct another blower door test once the windows, plumbing and electrical systems are installed.