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Determination of air permeability of the building using the blower door


The purpose of the leakage test is to determine the air permeability of the building (n50 values) and to verify that it satisfies the requirements. In accordance with the applicable 2008 Technical Terms, the required tightness is:

  • for buildings with gravitational ventilation n50 ≤ 3,0 h-1
  • for buildings with mechanical ventilation  n50 ≤ 1,5 h-1
  • for energy-efficient buildings it is recommended thatn50 ≤ 1,0 h-1
  • for passive buildings n50 ≤ 0,6 h-1

The aim of the leak test can also detect, document and repairing leaks.


  • Review of the technical documentation of the building
  • Analysis of comments submitted by the client
  • Perform a leak test with leak detection
  • Preparation of a test report covering the determination of the size of the derivative, eg n50
  • Indication of leaks and how to remove them


The tightness test is performed in overpressure and underpressure. There are two methods of testing: Method A - Building Survey, Method B - Building Inspection at the execution stage.

Sample table of contents:

  • Data necessary to identify the building
  • Legal basis
  • Description of research object
  • Description of apparatus and procedures
  • Measurement data
  • Air leakage chart
  • Derived quantities
  • Leakage and proposal to remove them

Legal basis

The leakproofness test is carried out in accordance with the method described in EN 13829 " Thermal performance of buildings. Determination of air permeability of buildings. Fan pressurization method”.

Measuring device

Leakage testing is performed using the Blower Door Model 4 air intake door with digital readout. The measuring range is from 19 to 7 200 m3 / h. The dimensions of the adjustable door structure are: width from 60 to 101 cm, height from 121 to 238 cm.

Measurement time

Measurement can only be carried out when the housing designed for testing the building or part thereof is completed. It is advisable to perform an initial measurement of the air permeability of the partition, which makes it possible to remove the leak more easily after the building has been completed.

Meteorological conditions

In case of product of the internal and external temperature difference (in Kalvins) and the height of the building's casing (in meters) equals more than 500 m • K, it is unlikely that a pressure difference under zero flow conditions exceeds 5 Pa. The same applies to situations in which the wind speed exceeds 6 m / s or reaches the third grade on the Beaufort scale. If the pressure difference in the zero flow condition exceeds 5 Pa, tests can not be performed.

On the leak test information provided

dr inż. Maciej Mijakowski, mmijakowski@nape.pl