The Tale of the Breathing Building: How Blower Door Testing Brings Homes to Life

The Blower Door Test

Continuing high energy prices only underline the necessity of energy-efficient building construction and rehabilitation. As part of environmental policy measures, legislators require airtight building envelopes for all new buildings. After all, air tightness is a prerequisite for realizing up-to-date energy concepts. Energy-efficient measures like installing state-of-theart heating systems or windows can only develop their full potential if undesired leakages in the building envelope are eliminated.

The blower door measurement allows us to test the air tightness of buildings. It can also protect against severe structural damage caused by warm and humid indoor air penetrating the building construction through joints. In addition, the indoor comfort level rises through the elimination of draughts or cold-air pools. When rehabilitating existing buildings, an air barrier planned according to the recognized standards often achieves current low-energy or even passivehouse standards. 

The Tale Of The Breathing Building

It is a myth that buildings need to have cracks and joints to “breathe naturally”. Such air change occurs in an uncontrolled manner. Too much or too little outdoor air will enter the building. Even worse, pollutants and dust from the insulation mix with the indoor air. A building should consequently be ventilated by frequently opening the windows or via a ventilation system.

A building is considered airtight when the air in the building under testing conditions is not exchanged more than three times per hour. In a building equipped with a ventilation system, the air change at testing pressure cannot exceed 1.5 times per hour. “Airtight” thus does not mean completely sealing a building, but rather avoiding undesired leakages in the building envelope. This is important because warm air flowing out through the joints costs energy. At the same time, the warm air transports moisture. It cools at the outside wall of the building and condenses. This condensation can cause severe structural damage. Outside air infiltrating the building through joints also transports allergens from the insulation and dust particles into the house, which can lead to ill effects on the occupants’ health.

Why Is It Important?

Air leaks can cost homeowners a lot of money in wasted energy. By identifying and sealing these leaks, blower door testing helps reduce energy bills. It also makes homes more comfortable by eliminating drafts and cold spots.

Moreover, a well-sealed home has better indoor air quality. It keeps out pollutants, allergens, and moisture. This is especially important for people with allergies or respiratory issues.

The Measuring Principle

We have been using the blower door for air tightness measurements  since its commercial release in the late 1980's.  Today it is one of the most successful testing devices for air tightness worldwide. IR thermography during the blower door measurement optimally completes the test of the building envelope, delivering comprehensive results and conducive evidence of the condition of the building envelope. These conclusions are illustrated and documented within the quality assurance process.

There Are Many Reasons For A Blower Door Test

Therefore, the objective of the measurement should be agreed upon in advance.

We Recommend The Blower Door Measurement

1.  For quality assurance during the construction phase

2.  As a final measurement after completion of the construction process

3.  Before expiry of the warranty (airtightness is owed permanently, not only on the day of measurement)

4.  In existing buildings for damage analysis or before a planned refurbishment.

A serious blower door measurement always includes quality assurance (leakage detection) and is an investment that pays off in any case.