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Tightening Your Airtightness

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As our industry looks at updating the National Construction Code in 2019 there is an increasing focus on the role that airtightness will play in our industry going forward. Building tightness testing and envelope construction can be used as an operational solution to address poor air tightness in Australian buildings, however the code update process has shown that this is often difficult to quantify in the design stage. Leakage can be affected significantly by wind, internal stack effects and combustion ventilation and these air leakages can account for as much as 15% of energy usage in a building directly correlating to operating cost.

Updates to the National Code of Australia are slowly bringing in measures of airtightness with the code proposals making this testing a key plank in two of Australia’s climate zones, however there is a view that implementing testing and compliance requirements can improve energy efficiency and indoor environment quality. These changes will come into force next year making it vital to educate the construction industry in methods and techniques of fa├žade and building fabric sealing and air tightness.

CIBSE ANZ is addressing this issue with seminars in Adelaide and Sydney in the past month. Mark Jacobsen, Managing Director of Flowtech, gave an informative talk on Building Envelope Testing (BET) in Adelaide, using case studies of projects that included Lucas Heights Nuclear Research Building and data centres as well as examples of where poor installation resulted in air leakage. He outlined the method of testing with a VSD controlled door fan capable of up to 3,000l/s to pressurise the building to between 50 to 80 Pa. and how to accurately measure the air leakage.

CIBSE NSW delegates heard from Chris Nunn, Head of Sustainability, Real Estate at AMP Capital and Jeff Robinson, Global Sustainable Design Expertise Leader at Aurecon. Together they explained the upcoming changes to the National Code of Australia and how the industry can prepare themselves, contractors and clients. The changes in 2019 will include minimum requirements for buildings and align with international standards (i.e. Part L in the UK) but only for locations where modelling is able to quantify the energy savings (climate zones 1 and 8). However, as we see these requirements implemented there is a logical progression that this will increasingly apply to projects, and as such, compliance and testing will become a growing industry. Jeff Robinson presented on a proposal for thermography and airtightness testing data to become a part of residential building hand over data, akin to electrical safety and plumbing certificates. This has the benefit of creating a consistent industry standard and check that homeowners can understand and assess, while creating a differentiator for those that are building well sealed houses. 

The key takeaway from these events was that if we “build tight, ventilate right” we will be able to much better control the indoor environments of our buildings while improving energy efficiency. Translating the technical jargon into easy to understand ratings like what we have seen with the NABERS program will enable builders and developers to show their customers the quality and care that has gone into their buildings.  Despite what the modelling is able to calculate at this point the feeling in the room was that sealing buildings make sense in the same way that closing your window when the air conditioner is on does. 

For more information on the changes to the code or building sealing standards please visit:
ABCB Code updates
Australian Passive House Association 
CIBSE Guide TM29

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