Building Air Leakage Resource Centre

by John Herbert (@johnherbert)

For building owners building air leakage costs extra money, whether it is through the additional energy use or poor indoor environmental quality. The latter, infiltration of polluted outdoor air and Radon are both a serious health concern impacting occupants.

Attempting rectification after occupation/renovation is always more difficult and time consuming, so the execution of the construction work is vital, we know it has a major impact on the airtightness of buildings.

Air leakage can be tested and verified during construction, using a 2 stage process using blower door test, supported with thermography (Infrared) and fog testing, to ensure unwanted air leakage is minimised.

In 2004 HK BEAM created 4/04 green building rating tool for new buildings, that introduced air leakage testing, and later in 2012 BEAM PLUS Interiors rating tool introduced air leakage testing for shops and offices, but regulation has not followed. Europe now has strict regulations requiring new buildings to undergo air leakage testing, to meet the country standard.

John Herbert organised air leakage seminar in 2015

Therefore to help reduce building energy use and wasting energy, air leakage standards and testing are needed here in Asia.

Air Leakage Frequently Asked Questions (FAQ)

What is Building Air Leakage?

A building envelope with openings, sometimes due to poor construction, allows polluted outdoor air into the building.

What are the consequences of air leakage in buildings?

In Asia, air infiltration has several consequences:

  1. allowing hot humid air to enter an air conditioned building, causes condensation on interior surfaces, providing the right environment for growth of mould inside buildings;
  2. poor indoor air quality impacts the health of occupants;
  3. increased energy use;

How to Identify Building Air Leakage?

Air leakage can be detected using blow door test, thermography, fog testing to identify the location of the air leakages, but in most cases these do not quantify the amount of leakage corresponding to each leakage.

What is the Key Issue for Buildings with Curtain Walls

According to the ASTM standard for curtain wall construction, curtain wall have permitted air leakage rate that qualifies for the ASTM standard. ( xxx litres/sec at 300pa). that means buildings with curtains walls have air leakage.

Resources (suggest a resource?)

Retrotec blower door Online Training

German Air Leakage Association Handbook (Chinese)

German Air Leakage Association Handbook 2 (Chinese)

Building Air tightness article by John Herbert (HK)

Air Change in Low and High-Rise Apartments research (HK)

A Guide on Indoor Air Quality Certification Scheme for Offices and Public Places 2019 (HK)


Passive Haus Guide (UK)

Analysis of Large Building Air Leakage
Testing DOD (USA)

Air Testing Standard Military (USA)

ATTMA Air Testing Standard 1 (UK)

ATTMA Air Testing Standard L2 non-domestic (UK)

BEAM Plus – Interiors rating tool (PDF)

HK BEAM 4/04 version (PDF page 1-20)


tightness EU newsletter (PDF) Nov. 2020


  1. CAN/CGSB 149.15 – Determination of the Overall Envelope Airtightness of Buildings by the Fan Pressurization Method Using the Building’s Air Handling Systems
  2. The United States Army Corps of Engineers Air Leakage Test Protocol for Building Envelopes
  3. ISO 9972:2006 – Thermal performance of buildings — Determination of air permeability of buildings — Fan pressurization method
  4. ASTM E779 – Standard Test Method for Determining Air Leakage Rate by Fan Pressurization
  5. ASTM E1827 – Standard Test Methods for Determining Airtightness of Buildings Using an Orifice Blower Door
  6. EN 16798-3: 2017: “Energy performance of buildings – Ventilation for buildings – Part 3

tags: air leakage, infiltration, exfiltration, permeance, building envelopes, airtightness