The Zone Pressure Diagnostics (ZPD) Calculation Utility provides a way to estimate the leakage from one zone to another.   It can help to prioritize air sealing activities.   The ZPD Calculation Utility uses Minneapolis Blower Door tests taken with the house closed with zone pressure taps to the garage, the attic or the crawlspace.   An opening is then made to the suspected zone, such as opening a door, and then running the Blower Door test again and noting changes in the zone pressures.