A climate-based moisture index approach for hygrothermal analysis in Australia

Abstract

In Australia, one-third of new constructions are affected by condensation and about 50% of buildings suffer from mould risk, mainly due to inappropriate design and management strategies. Despite the potential structural damage and serious health hazards, there is a lack of preventive moisture management strategies at the legislative level. The first hygrothermal management provisions were adopted in the National Construction Code only in 2019, with very general indications that correlate the breathability of the membranes with the climate zone. However, the building code identifies only eight zones for the entire Australia, which were originally developed for thermal analysis and energy efficiency provisions. The result is a coarse climate grid that clusters locations with highly variable humidity conditions. This paper undertakes a semi-empirical approach to identify whether the current climate zones are suitable for hygrothermal purposes. This research represents the first step towards an Australian-specific moisture risks management framework, and it advances the discussion about the suitability of the current hygrothermal design and construction policy and practices. The outcomes reveal the highly variable moisture indices obtained for the different representative cities, affirming the inappropriate use of existing climate zone clustering for hygrothermal assessment purposes.