Blower door testing in Australia
National construction code is finally trying to bridge the gap around design performance and actual performance!
An exert for Class 1 buildings (Residential) from the new NCC 2019
V18.104.22.168 Verification of building envelope sealing
Compliance with P2.6.1(f) is verified when a building envelope is sealed at an air permeability of not more than 10m3/h/m2@50Pa reference pressure when tested in accordance with AS/NZS ISO 9972 Method 1
The intent is that 10m2/h/m2@50Pa is broadly equivalent to 10air changes per hour at 50Pa when applied to homes. It should be noted that V22.214.171.124 is only one way of achieving compliance with P2.6.1(f). Other ways of complying include the following:
a) The relevant provisions of Part 3.12.3.
(b)A Performance Solution that uses one of the other NCC Assessment Methods which verifies that compliance with P2.6.1(f) will be achieved.
exert from NCC2019
|Type 1||Method A - Building in use test||Method 1 - Building in use test||Building in a closed state, dampers closed, and nothing temporarily taped/sealed up. Ventilation systems running 24/7 can be sealed up.|
|Type 2||Method B - Building Envelope Test||Method 2 - Building Envelope Test||HVAC and Exhaust systems/strategies taped up and isolated from the blower door test. Air Leakage attributed to poor draught stoppers or leaky ductwork/plenums are hidden. This is a Building envelope test only.|
|Type 3||-None-||Method 3 - Specific Purpose test, such as compliance tests with particular inventories of items, closed or sealed.||Shall be documented in a specification by engineers|
exert from ISO 9972
What does it all mean?
Build quality testing is finally here! We have copied what was introduced to the UK, except with a little twist. Aurstralian air tightness testing requires no temporary sealing of HVAC or intermitent ventialtion systems. seee the table below.
|Classification of openings of buildings||Building in use|
|Ventilation openings for natural ventilation||closed only||temporarily sealed||As Documented|
|Openings for whole building mechanical ventilation or air conditioning||temporarily sealed||temporarily sealed||As Documented|
|Openings for mechanical ventilation or air conditioning (only intermittent use)||closed only||temporarily sealed||As Documented|
|windows, doors, and trapdoors in evvelope||closed only||closed only||As Documented|
|Openings not intended for ventilation||closed only||temporarily sealed||As Documented|
exert from ISO 9972:2015
Australia, can finally start producing and policing homes with a high performance air barrier, thanks to a non mandatory option for compliance to test that a home is below 10m3/h/m2@50Pa (equivilent to 10AirChanges an Hour@50Pa). This target provides an objective scale/target that everyone agrees is possible to achieve and reasonable to expect.
What is the building envelope?
Envelope, for the purposes of Part 2.6 and Part 3.12 in Volume Two, means the parts of a building’s fabric that seperate artificially heated or cooled spaces from—
a. the exterior of the building, or
b. other spaces that are not artificially heated or cooled.
exert from NCC2019
Bathrooms, toilets and laundries are considered to be INSIDE the building envelope. the air barrier follows the insulation barrier, there must be no air gap between the 2 details of the building envelope.
If you are getting air tightness testing done. Make sure your air tightness tester is being conducted to Australian standards with dampers closed , and not taped. This Method B/2 process hides issues in your building.