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Leaky houses have their own set of problems - such as drafts and overworked air-conditioning systems - resulting in a house that will not adequately heat or cool, resulting in ever-increasing energy costs.

What is a blower door?

A blower door is a machine used to measure the airtightness of buildings. It can also be used to measure airflow between building zones, to test ductwork airtightness and to help physically locate air leakage in the building structure.

There are three primary components to a blower door:

•  a calibrated, variable-speed fan, capable of producing a range of airflows to pressurize and depressurize a variety of building sizes;

•  a pressure measuring instrument, called a manometer, to simultaneously measure the pressure differential induced across the face of the fan and across the building envelope, as a result of fan airflow; and

•  a mounting system - used to mount the fan in a building opening - such as a door or a window. Watch a video of a blower door operating.

Why is it important?

Air Tightness Testing is the process of determining the amount of air leaking from inside (heated air in winter or cold air in summer) to outside (waste of money, CO2). The test method itself is straightforward. We install a fan into a doorway of the building and draw air through the fan out of the property to create a negative pressure inside the house. Because we are measuring how much air is going through the fan, we can calculate how much air is escaping and therefore determine the house leakage rate i.e. the number of air changes per hour (ACH).