Blower Door

The door to your well-being

Detached houses, multi-family houses, commercial buildings – We are your specialists for blower door testing of small to large buildings

  • We check the airtightness of small to large buildings, such as single and multi-family houses, industrial halls, office buildings, cold stores, freezers, logistics halls, non-residential buildings, gymnasiums, hypermarkets, gyms, swimming pools, sports halls, passive houses and other buildings


  • SYSWE relies on reliable and powerful measuring instruments for airtightness measurement


  • Detection of leaks by thermography

The increased energy demand caused by high air leakage is significant. Thus, in a detached house due to leaks energy losses in the amount of 500 to 600 euros annually occur. Eliminating weak spots in the building envelope has sustainable advantages: Energy is saved – this saves costs and the environment – and building quality increases – so does the quality of life and the value of the property. In addition, the blower door test serves as proof for KfW loans (KfW Efficiency House) and is a basic prerequisite for buildings with ventilation systems. Passive houses in particular are subject to stricter norms and laws.

The specialists from SYSWE are your competent and reliable partner with many years of experience for a blower door test on your building. Are you looking for an expert in air density measurement? Contact us!

How does the Blower Door test work?

We use a Blower Door measurement device, which consists of a frame that is placed in the door or window opening and a high-performance fan to create the differential pressure. The frame is covered by a blanket (red colored in the picture) to seal the door opening airtight. Special measurement instrumentation is documenting the pressure difference during the test.

In the beginning of the measurement an under- or overpressure is created in the building. This helps to locate the leakages and to calculate the air exchange rate (n50). The air exchange rate indicates how often the air volume of the building is exchanged at a constant pressure of 50 Pa.

Reasons for a Blower Door test

The Blower Door test is used to verify the airtightness of a building.

A high airtightness means

  • a lower energy loss
  • a reduction of the risk of structural damages and mould formation resulting from high humidity
  • a constant comfortable temperature
  • no efficiency loss of the ventilation system
  • a good noise protection

The Blower Door test is possible in the inhabited or uninhabited building. After the measurement procedure you’ll get documentation with the results.

You are interested in a Blower Door test or need more information? Contact us!


What is a Blower Door Test?

The Blower Door Test is a procedure to check buildings on inadvertent air exchange (air leakages) between the inner building envelope and outdoors and to locate the leakages. Also individual rooms or building sections can be checked.

Why should I perform a Blower Door Test?

To gain an optimal comfortable living and to minimize the therefore necessary energy. In addition the test is a certificate for KfW credits.

Why should a building be as airtight as possible?

After §6 of the energy saving regulations (EnEV, 2014) a building owner is obligated to build the house permanently airtight. “Airtight” means the whole building envelope is as airtight as a walled and plastered wall. This is especially for the energy saving, because a lower loss of heated (or cooled) air means also lower heating (or cooling) effort to gain the right temperature.

Why perform a Blower Door Test when I am already living in the building?
  • Airtightness means no unnecessary energy consumption by heat loss
  • Leakage means draught in the rooms
  • Condensate formation can occur inside the insulation plane
  • An increasing moisture penetration can occur
  • Increasing loss of insulating effect
  • Mould formation in the rooms possible
  • Moisture damage in the brickwork and wood construction
How is a Blower Door test performed?

A Blower Door measurement device is clamped into the door or window. Additional locations were air can disappear are sealed previously, like elevators or open pipes. While the measurement the air exchange rate is determined with the help of over- or underpressure.

Which measurement values are determined with the test?

The measurement values are represented according to international standards. The air exchange rate [1/h] n50 at a pressure difference of 50 Pa is determined.

What are the costs of a Blower Door Test?

The costs depend on the inner volume of the building. Please call us, we prepare a non-binding offer for you, adjusted to your requirements.

Are there any reference values that have to be observed?

Yes, there are reference values. Airtightness is state of the art since the DIN V 4108-7 (11/1996) and after the publication in the Federal Gazette No. 140 it is generally accepted technical regulation of the Heat Insulation Ordinance 95. The unrequested performance of the Airtightness by the construction manager is therefore provided.

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Boris Rieken
Boris Rieken

Tel.: +49 4222 - 805 805 0

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