Hygrothermal assessment is essential to the production of healthy and energy efficient buildings. This has given rise to the demand for the development of a hygrothermal laboratory, as input data to hygrothermal modeling tools can only be sourced and validated through appropriate empirical measurements in a laboratory. These data are then used to quantify a building’s dynamic characteristic moisture transport vis-a-vis a much more comprehensive energy performance analysis through simulation. This paper discusses the methods used to establish Australia’s first hygrothermal laboratory for testing the water vapor resistivity properties of construction materials. The approach included establishing a climatically controlled hygrothermal test room with an automatic integrated system which controls heating, cooling, humidifying, and de-humidifying as required. The data acquisition for this hygrothermal test room operates with the installation of environmental sensors connected to specific and responsive programming codes. The room was successfully controlled to deliver a relative humidity of 50% with ±1%RH deviation and at 23 °C temperature with ±1 °C fluctuation during the testing of the water vapor diffusion properties of a pliable membrane common in Australian residential construction. To validate the potential of this testing facility, an independent measurement was also conducted at the Fraunhofer Institute of Building Physics laboratory (IBP) Holzkirchen, Germany for the diffusion properties of the same pliable membrane. The inter-laboratory testing results were subjected to statistical analysis of variance, this indicates that there is no significant difference between the result obtained in both laboratories. In conclusion, this paper demonstrates that a low-cost hygrothermally controlled test room can successfully replace the more expensive climatic chamber.

To reduce greenhouse gas emissions, nations have introduced energy efficiency regulations for new and existing buildings. This has been considered advantageous as more efficient building envelopes would reduce energy consumed to heat and cool home interiors to within accepted thermal comfort bandwidths. However, as these methods have been adopted, many nations have identified an unintended visible presence of surface and interstitial condensation and mould in new code-compliant buildings. In Australia, it has been estimated that up to 50% of Australian houses constructed in the last decade (2006–2016) have a presence of condensation and mould. Australia introduced its first condensation and mould-related building regulations for new homes in 2019. This paper reports on the hygrothermal and mould growth analysis of the most common low-rise residential external wall system, a timber-framed clay masonry veneer wall. A key component of this paper discusses the application of innovative methods in the Australian context. The external wall’s moisture accumulation and mould growth were simulated for a period of ten years using the transient hygrothermal simulation tool, WUFI^® Pro, and the mould growth model, WUFI^® VTT. This study identified significant risks for this typical external wall system when constructed in a temperate climate.

Hygrothermal modelling is increasingly used to inform building envelope design. A key input for these calculations is the material’s vapour diffusion properties. Respecting a growing international concern, this research has questioned the appropriateness of the current test method to establish construction material for vapour diffusion properties. This article reports on the empirical measurement of the vapour diffusion properties of two vapour-permeable building membranes commonly used in Australia residential systems when subjected to variable relative humidity conditions. The method involved completing dry cup and wet cup standard tests as specified in ISO 12572, (23 °C and 50% relative humidity RH). Further tests were then conducted as temperature remained at 23 °C but the relative humidity changed to 35%, 65% and 80%, respectively, in order to know if the diffusion properties are the same or change with varying relative humidity. The results from the wet cup and dry cup tests under different relative humidity conditions were non-linear and different. These results indicate vapour-permeable membranes behave differently when exposed to different relative humidity conditions. In conclusion, this research demonstrates that the current vapour resistivity test method is inadequate, hence the need to establish more detailed diffusion resistivity properties in different humidity ranges that represent conditions experienced within a building’s external envelope.

The energy efficiency performance requirements of the Australian National Construction Code have been regularly enhanced since 2003 to reduce greenhouse gas emissions. Since 2010 research has increasingly raised a concern about high air moisture content, moisture accumulation and mould growth. Coincidently, in Australia, asthma is the leading cause of disease in children aged 0–14 years, accounting for 17.9% of the total burden in boys and 18.6% in girls. Many researchers have supported a connection between damp housing and childhood respiratory symptoms. The contemporary code compliant houses in Australia may have inadvertently created ideal interior environments that promote mould growth. If the built environment is promoting mould growth, leading to sick building syndrome, it is a matter of serious concern, resulting from the design or technical flaws in the building fabric. This paper attempts to bridge the gap between architectural and medical science perspectives in this area of study.

Moisture-related damage is still a formidable cost factor in the building sector. Besides installation deficiencies, moisture control design failures are the most frequent reasons for moisture problems. Therefore, adequate moisture control analysis has become the key for sustainable buildings. However, by only focusing on vapour diffusion other important moisture loads such as driving rain, construction moisture or air infiltration are mostly neglected. Therefore, international moisture control standards often refer to simulation models for more realistic analysis, leaving many practitioners wondering how to handle these tools. To overcome this dilemma, the updated German moisture control standard has introduced a three-pathway approach for design evaluation: first, deemed to satisfy list, second, restricted Glaser calculation and third, fully fledged hygrothermal simulation. The third pathway includes the option to account for small leaks or imperfections in building envelope components. Guidelines in other countries are also embracing similar moisture control approaches which gives hope for more durable and sustainable building design. To reach this aim, moisture control should also become an integral part of the design process instead of a secondary chore.