What is a Blower Door?

A Blower Door is a tool for measuring the airtightness of buildings. It can be used for quality control to help find leaks, and it can very precisely measure the amount of air leakage. It is so good at this that it is used by building codes around the world to verify standards for air tightness in construction.

How does it work?

The Blower Door is a calibrated fan that is used to draw air into or out of a building. This creates a pressure difference which a super-accurate micromanometer (pressure gauge) can measure. The air flow through the fan is measured and compared to the pressure difference. With a few standard calculations, a very accurate estimate of leakage under pressure is measured!

Why is building more airtight the smart way to go?

Check out these videos for a great overview of some great reasons why air leakage through the building envelope does so much more harm than good.

Simple quality control with a Blower Door

You can use a Blower Door very simply to assess quality of air tightness. Even with basic training, a rough idea of performance can be readily determined. That’s why for high-performance builders, a Blower Door is a common sight throughout the construction process! Test early and often to really make improvements. Fixing leaks early in construction is much cheaper than trying to locate and fix them at the end.


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