Recent increases in the occurrence of condensation and mould within new Tasmanian housing

Tasmania, located in southern Australia, is a cool-temperate climate. For several months, the external environment is cooler than the desired minimum temperature for thermal comfort. However, this same climate has many days in the hotter months when the external temperatures are above those desired for thermal comfort. This creates a scenario where heating is used extensively, and during the warmer months, houses are also increasingly cooled. Combined with enhanced thermal performance regulations three distinctly different, yet interlinked consequences have evolved. Firstly, the newer homes are much warmer in winter, providing thermal comfort and human health benefits. The increase in envelope performance has enabled and created greater differences in vapour pressure between the conditioned and unconditioned interior spaces and the external environment. Finally, the better performing envelope has led to an increase in thermal comfort expectations, where reverse-cycle air-conditioning is often operated 24 hours a day, 7 days a week. These factors have led to a significant increase of internal surface and interstitial condensation within many new homes. This paper discusses recent condensation problems encountered within Tasmania, which has established significant knowledge and practise deficiencies within the design and construction professions in relation to climate based vapour pressure management within buildings.