Mark Vender
The authors of a new study hope their work will act as a catalyst for industry change as Australia moves to net-zero-carbon housing. As well as providing in-depth technical information on moisture management and airtightness, it recommends how construction practices need to change to achieve highly energy-efficient, durable and healthy buildings.
An Australian Based Study On Airtightness and Moisture Management was published by Pro Clima, and authored by Jesse Clarke, M.AIRAH, and Lothar Moll, with input and review from international experts. According to Clarke, it came about when his organisation began investigating building science in the Australian climate.
“The international trend that has occurred in many developed countries is that housing starts to have moisture-related health issues as insulation and airtightness increase,” Clarke explains. “This happens when the sole focus is put on energy without understanding the effects it has on the building envelope.”
In Australia, some have certainly suggested that making our buildings more airtight will lead to condensation and mould. Clarke disagrees.
“The relationship between energy efficiency and health is not a trade-off,” he says. “When done correctly, a more airtight and well-insulated building is actually a healthier, more durable and more energy-efficient building. This is what the study is about – how to do it correctly.
“The fundamental basis of building science is to tune the construction systems to the climate and this largely comes down to the vapour permeability of membranes. The principles by which high-performing buildings operate all centre around airtightness. Airtightness gives greater control of heat and moisture, but the prerequisite for healthy buildings is that the materials layers used to make the systems airtight are appropriately selected based on the local climate.”
Accordingly, Clarke says the study aims to plug the knowledge gap between how houses are currently built in Australia and how they should be built.
“The Proclima CEO asked me several years ago if it was possible to leapfrog the problems that the rest of the world has had: the sick building crisis, the leaky building crisis, the mould crisis,” says Clarke. “My answer was ‘possibly not, but we are going to try’.”
Included in the study are computer-based simulations of the combined heat and moisture transport of wall assemblies; a roof construction review; and a field study of state-of-the-art construction practices in Australia. When it comes to construction practices, Clarke notes that some parts of the industry are already embracing new approaches.
“The builders are the true innovators,” says Clarke, “the ones who have to make everything work. But most importantly they prove that better is possible. They are the link between the theoretical and the real world. Particularly important are the ones who operate with more than just price and cost in mind but rather have a better sense of value and want to contribute to the process of industry change. Their work is showcased in this document.
“It’s a piece of work that will hopefully be used as a guiding light for policy-makers, architects and builders.”
The study can be downloaded from the Proclima website.
Photo by Andrew Seaman on Unsplash
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