Using a Blower Door During an IR Inspection

Data obtained during infrared inspections can often be improved by incorporating other tools. When it comes to building inspections, a blower door can be useful in detecting air leakage sites and helping to gauge the airtightness of a building.


Air leakage is often a major source of energy loss in buildings. Although an infrared imager can help detect evidence of air leakage sites, it cannot pinpoint all air leakage sites nor can it quantify the amount of air leakage occurring. Many thermographers overcome these limitations by utilizing a blower door in conjunction with their infrared inspection.


A blower door consists of an instrumented, high volume fan that is temporarily placed in a doorway to create a positive or negative pressure within a building. In depressurized mode, the blower door simulates a wind blowing equally on all sides of the building. Conducting an infrared inspection with the building depressurized enables a thermographer to detect air leakage sites that would not be visible under natural conditions. With special software, it is possible to estimate the relative leakage of a structure as well as the total area of all leak sites.