Mark Dewsbury, M.AIRAH

University of Tasmania
Challenges on the regulatory journey

Since 2008, researchers at the University of Tasmania have been liaising with building regulators regarding Australia’s imminent “leaky building syndrome”. These experiences occurred in many northern hemisphere nations in the 20th century and early in the 21st century for New Zealand. The same problems may have been present in Australian buildings since the 20th century, but the regulatory framework and building occupant expectations in Australia have been quite low. For more than a century we have blamed condensation and mould in houses on the building occupant and not on the building. 

We now have some regulations regarding condensation and mould in Australian homes. For many Australian climate zones, we are now required to consider roof space ventilation, permeable membranes in external walls, and some forms of exhaust ventilation. And if we are unsure, we need to apply the transient simulation method, as described in DA07. These are all positive steps, but are they enough? Where is the exhaust ventilation supply air coming from? How does moisture drain from a code compliant external wall? What inputs are consultants using when completing transient hygrothermal simulations?

Before it was adopted nationally, the Nationwide House Energy Rating Scheme was developed over nine years between 1993 and 2002 in order for governments and industry to agree on all the inputs. Similar developmental patterns are observable for many areas of building regulation, like roofing, insulation, water control and fire control. In the context of NatHERS, this has included national climate data sets, interior thermostat settings, and a national materials database.

One could say that the current use of hygrothermal simulation is like the wild west. What inputs are used and why are those inputs chosen? And how might simple choices affect the results? This presentation will explore some of the challenges facing transient hygrothermal simulation. 

About Mark Dewsbury:
Mark Dewsbury is passionate about the pathway to net-zero and sustainable buildings. His professional experience includes more than 30 years within the public and private sectors. As a Senior Lecturer and post-doctoral researcher at the University of Tasmania, he focuses his research on methods of designing and building to improve the construction, thermal performance and indoor environmental qualities, and minimise mould and condensation in buildings. His team of post-graduate researchers are exploring the systemic, regulatory and industry knowledge gaps associated with significant risks to IEQ and durability during our transition to high-quality, low-carbon and net-zero buildings.