Zone pressure diagnostics (ZPDs) are used to identify and measure series leaks, or leaks that pass through several zones of the house. For example, air leaking through the attic roof must first move from the living spaces into the attic through the attic floor. ZPDs measure the pressure difference between the living space and the bordering zone (such as the attic), and between the bordering zone and the outdoors. These bordering zones can also be basements, garages, kneewall areas, or particular rooms.
ZPD testing relies on the principle that the ratio of the pressure difference across the interior and exterior boundaries of a series leak is a direct function of their leakage area. Michael Blasnik developed the set of ZPD techniques known as the Blasnik methods. Ever since, these methods have become well established among weatherization crews,
with hundreds of users across the country. ...
Read more in David Bohac's Home Energy Article, "Zone Pressure Diagnostics" in the May/June, 2002 issue.