🌀 Blower Door Airtightness Test

Construction PN-EN ISO 9972

Overview

STATUS (as of 06.11.2026). PN-EN ISO 9972:2015-10 “Cieplne właściwości użytkowe budynków — Określanie przepuszczalności powietrznej budynków — Metoda pomiaru ciśnieniowego z użyciem wentylatora” (Thermal performance of buildings — Determination of air permeability of buildings — Fan pressurization method) — English version, published 26.10.2015, implements EN ISO 9972:2015 and ISO 9972:2015 [IDT]; it replaced PN-EN 13829:2002 (Polish version). The card has no withdrawal note — the standard is current. ISO 9972:2015 (third edition, 10.08.2015) replaced ISO 9972:2006; EN ISO 9972:2015 replaced EN 13829:2000. In PCA accreditation scopes (copy of the database of 06.11.2026) the standard appears as PN-EN ISO 9972:2015-10.

SCOPE AND USE (introduction, clause 1). The standard is intended for measuring the air permeability of buildings or parts of buildings in the field: overpressure or underpressure is created mechanically and the air flow rates are measured over a range of indoor–outdoor static pressure differences. It applies to the envelopes of single-zone buildings; many multi-zone buildings can be treated as single-zone by opening interior doors or by inducing equal pressures in adjacent zones. It does not address the air permeability of individual components. The result can be used, among other things, to check compliance with a design airtightness specification, to compare similar buildings and to assess the reduction of air leakage after successive retrofit measures. The method does not measure the air infiltration rate — this can be estimated from the results by calculation or measured by another method, e.g. tracer gas. Ideal test conditions are small temperature differences and low wind speeds; strong winds and large indoor–outdoor temperature differences are to be avoided.

STRUCTURE OF THE STANDARD (table of contents). Apparatus (clause 4): air-moving equipment, pressure-measuring device, air flow rate measuring system, temperature-measuring device. Procedure (clause 5): measurement conditions, measured extent, time of measurement, building preparation methods, heating, ventilation and air conditioning systems, intentional openings in the envelope, openings inside the measured extent, preliminary check, temperature and wind conditions, zero-flow pressure difference and pressure difference sequence. Results (clause 6): internal volume, envelope area, net floor area, calculation of the air leakage rate and derived quantities — air change rate at the reference pressure difference, specific leakage rates (per envelope area and per floor area), effective leakage area. Then: test report (clause 7), uncertainty (clause 8) and informative Annexes A–E (equipment, air density, uncertainty estimation, Beaufort scale, leakage location).

WHAT THE 2015 EDITION CHANGED (according to a summary by a European knowledge platform on building airtightness). The former building preparation methods A and B were replaced by methods 1 and 2, and a method 3 for specific purposes was added, which individual countries may define in their own regulations (e.g. sealing certain natural ventilation openings in line with the energy performance calculation). When the measurement serves to check compliance with a code or standard, the measured extent is defined as in that document. If an opening cannot be closed, it remains open. The pressure-measuring device has an accuracy of ± 1 Pa in the range from 0 Pa to 100 Pa, the temperature-measuring device 0.5 K. The internal volume includes internal walls and floors. The coefficient of determination r² of the linear regression shall be at least 0.98. 50 Pa is no longer the default reference pressure difference — another one may be chosen. An informative note gives an overall uncertainty of about 10 % in calm conditions and about 20 % in windy conditions. The test report gives the building volume and the position of the sealing of the mechanical ventilation.

REGULATION. The Polish regulation on technical conditions for buildings and their location (consolidated text Dz.U. 2022 item 1225), in Annex 2 item 2.3.3, gave the recommended airtightness of buildings: n50 < 3.0 1/h in buildings with natural (gravity) or hybrid ventilation and n50 < 1.5 1/h in buildings with mechanical ventilation or air conditioning, and in item 2.3.4 recommended an airtightness test after completion of construction according to the Polish Standard on determining the air permeability of buildings. In the Sejm ELI database (read on 06.11.2026) the regulation has the status “uznany za uchylony” (deemed repealed) with the date 21.09.2026.

WHAT WE DO NOT GIVE HERE. The available preview of the standard ends with the introduction — details of the building preparation methods (table in 5.2.3), the values of the lowest and highest pressure difference and the number of measuring points, the formulae for calculating the air leakage rate and requirements for weather conditions are known to us only from the summary of changes, and therefore we do not give them. We do not give requirements of subsidy programmes or passive house standards — none of the available sources contains them.

Method principle

A fan mounted in an opening of the envelope (for example in the external door) creates overpressure or underpressure in the building or part of it. At a series of indoor–outdoor static pressure differences, the air flow rate through the fan, equal to the leakage flow rate through the envelope, is measured.

From the regression results (r² at least 0.98) the air leakage rate at a chosen reference pressure difference and derived quantities are calculated: the air change rate (e.g. n50 at 50 Pa), specific leakage rates and the effective leakage area. The building is prepared by one of methods 1, 2 or 3.

Applications

• Checking a building or part of a building for compliance with a design airtightness specification (introduction to the standard)
• Comparing the air permeability of similar buildings or parts of buildings (introduction to the standard)
• Assessing the reduction of air leakage after successive works on an existing building (introduction to the standard)
• Basis for estimating the air infiltration rate by calculation — the method itself does not measure infiltration
• Locating leaks while maintaining a pressure difference (informative Annex E)

Key parameters

Standard

Standard number

PN-EN ISO 9972:2015-10

Title (PL)

Cieplne właściwości użytkowe budynków — Określanie przepuszczalności powietrznej budynków — Metoda pomiaru ciśnieniowego z użyciem wentylatora

Title (EN)

Thermal performance of buildings — Determination of air permeability of buildings — Fan pressurization method

Step-by-step procedure

1. Measured extent and preparation method

   Define the measured part of the building (when the measurement serves compliance with a regulation — as defined in that regulation) and choose preparation method 1, 2 or 3 (5.1.2, 5.2.1).

2. Building preparation

   Prepare the heating, ventilation and air conditioning systems and the intentional openings in the envelope according to the chosen method; an opening that cannot be closed remains open. Open the openings inside the measured extent (e.g. interior doors) (5.2.2–5.2.4).

3. Installing the equipment

   Install the air-moving equipment and the pressure-measuring devices (5.2.5–5.2.6).

4. Preliminary check and conditions

   Carry out the preliminary check, record the temperature and wind conditions; avoid strong winds and large indoor–outdoor temperature differences (5.3.1–5.3.2, introduction).

5. Zero-flow pressure difference

   Measure the pressure difference with the fan switched off; its average is used to establish the lowest pressure difference in the sequence (5.3.3–5.3.4).

6. Pressure difference sequence

   At successive pressure differences (overpressure or underpressure) measure the air flow rate through the fan (5.3.4).

7. Calculations

   Calculate the air leakage rate from the regression (r² at least 0.98) and the derived quantities at the chosen reference pressure difference: air change rate, specific leakage rates, effective leakage area (clause 6).

8. Test report and uncertainty

   In the test report give, among other things, the building volume and the position of the sealing of the mechanical ventilation; estimate the uncertainty (clauses 7–8, Annex C).

Required equipment and apparatus

Health and safety (OHS)

• The available text of the standard gives no safety requirements — the rules for working at the fan and in a building with combustion appliances are set by the contractor on the basis of a risk assessment

Frequently asked questions