A hygrothermal analysis of 6 Star envelope systems used in code compliant homes in Victoria

The correlation between energy efficient buildings and the increased risk of condensation and mould inside homes and within the built fabric of homes has been internationally recognised for more than nine decades. In the northern hemisphere, regulations and standards have been in use for more than five decades. However, the regulatory development in Australia has been tardy. Researchers at the University of Tasmania have been completing steady state, hybrid steady state and transient hygrothermal calculations and simulations for the last decade and much of this data has performed the back-bone for the “Condensation in Buildings –Tasmanian Designers’ Guide” which is referenced with the National Construction Code for Tasmania and the Australian Capital Territory. The guide is also used in Victoria. Recent research that has been exploring risks of moisture, moisture accumulation and mould growth in ‘code compliant’ 6 Star homes in Victoria. To gain an understanding of current problems in new housing and to plan recommendations for 7 Star housing, the Victorian Building Authority contracted the University of Tasmania to complete a series of hygrothermal research tasks. The first part of the research explored eleven external wall common external wall types used in external walls of Class 1 and Class 2 buildings, within NatHERS climates for Victoria. This paper reports the results of the hygrothermal analysis for the six of the simulated wall systems, demonstrated significant durability and human health risks in current construction practices.