Blower-Door-Measurement method

Airtightness measurement with Blower-Door-Measurement method

In well-insulated buildings, up to 60 % of the heating energy can be lost through joints and cracks in the building envelope. Energy-efficient construction can therefore only be achieved with a high degree of airtightness of the building envelope. Furthermore, this prevents structural damage due to condensation and prevents as well as drafts from penetrating, noise or odours. The blower door measurement method can be used to check the tightness of the building envelope.

Buildings should be free of damage, durable and fit for purpose. Hence SIA Standard 180 formulates requirements for the building envelope as well as limit and target values for airtightness. For buildings constructed according to the Minergie standard, airtightness measurements are recommended (Minergie®) or mandatory (Minergie-P® & Minergie-A®) for quality assurance.

Even with a successful measurement result regarding the general airtightness of the building envelope, a careful check for individual leaks must be carried out in order to prevent possible damage (e.g. due to condensation) to critical building components.

In addition to airtightness, the quality of the indoor air in Minergie-ECO® buildings must also be checked after construction completion (acceptance measurements). As a certified body for indoor air measurements (reference to our homepage), we can offer you these two services as unique interlocutor.

How does the blower door measurement method work?

The blower-door measurement method determines how often the air volume of a building is exchanged with outdoor air per hour at a certain pressure difference. In order to build up the differential pressure (negative or positive pressure), a fan is installed in an opening in the building. The output of the fan is controlled in such a way that a defined pressure difference is established between the outside and the inside. The air volume flow rate that the fan has to deliver while maintaining the pressure corresponds to the volume flow rates through leakages in the building envelope. The so-called air volume flow characteristic curve is calculated from this data.

During operation in negative pressure, leaks in the building envelope can be easily identified by hand, smoke tubes or thermography. Furthermore, during positive pressure operation, the air outlet points can be visualized with a fog generator.

Ecosens is a member of the Thermography and Blower Door Association Switzerland (theCH)

Our services include:

  • Preparation of the airtightness measurement concept and coordination with the Minergie ® certification body
  • Positive and negative pressure test with the blower-door measuring method
  • Determination of air exchange rates (qE50 - value) according to the guideline airtightness in Minergie buildings (RILuMi)
  • Leakage detection with fogging/thermography in case of non-fulfilment of requirements
  • Preparation of test certificates according to Minergie-P/-A® standard
  • Special investigations such as leakage detection with vacuum and fog generator or tracer gas (e.g. in case of pollutant/odour problems)

Your contact in German-speaking Switzerland:

Raphael Rapold Project manager: Indoor air quality
MSc. economic chemistry +41 44 839 47 90 More

Pascal Diefenbacher Divisional manager for indoor air quality
Dr. sc. Environmental Sciences (Federal Institute of Technology) +41 44 839 47 97 More

Case studies

Acceptance measurements of air tightness (Blower-Door)
Apartment building Soodstrasse 90, 8041 Zurich

The new apartment building at Soodstrasse 90 in Zurich, Switzerland, was constructed in accordance with SGNI (Swiss Sustainable Building Council) building label requirements (DGNB System, Switzerland). This certification required airtightness of the building structure to be scientifically measured.


Acceptance measurements of air tightness (Blower-Door)
Temporary laboratory FGCZ, University of Zurich Campus Irchel

The new construction of the provisional laboratory building of the University of Zurich at the Irchel campus in Zurich was carried out according to the specifications of the SGNI and Minergie-P-ECO building labels. For certification, the airtightness of the building envelope had to be tested by measurement.