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    Why Australia needs to join the Passive House movement

    Aurecon

    Improved building outcomes, such as greater levels of thermal comfort, a healthier work environment, lower energy costs and increased building structure longevity can all be achieved as a result of compliance with the Passive House Building Standard. 

    Passive house construction can provide high comfort and quality of life without sacrificing energy efficiencies or increasing costs, according to Johanna Trickett, environmentally sustainable design consultant at Aurecon. 

    “Australia and New Zealand are at the start of this journey and due to initial obstacles and challenges, such as a knowledge gap in industry as well as availability of products and materials, the Passive House Building Standard will likely incur greater costs than will be the case once this standard becomes normalised. However, the Passive House benefits of user comfort and energy efficiency outweigh the costs,” says Trickett. 

    Jesse Clarke, Building Science Manager, Pro Clima Australia, says the emerging issues that minimal compliance buildings are faced with include moisture and mould in cooler climate locations, and exacerbated summer cooling issues in warmer climate locations.

    “The Passive House Building Standard has solved both of these issues by delivering comfort through control over thermal fluxes over the building envelope, combined with adequate thermal bridging. This provides the stability of indoor conditions,” says Clarke.

    “Through air tightness considerations and implementation of the building standard, we see a balance in the moisture flows with the heat within the building envelope which results in a healthy, dry, high-performing building.”

    Susanne Hundert, associate at Aurecon, says Passive House construction requires very high levels of building fabric air tightness to provide the thermal comfort and low operating costs expected.

    According to Hundert, the key areas to consider when delivering a successful Passive House building is the building envelope and the building services. Both the envelope and services must be carefully considered at the same time during the design process.

    Improved health is achieved from factors such as enhanced indoor air quality (low CO2, volatile organic chemicals and other contaminant levels) and the greatly reduced requirement for supplementary heating and cooling, says Joel Seagren, Intelligent Ventilation Solutions Engineer at Fantech.

    “This reduces the risk of allergy and dehumidification effects that can be associated with HVAC air delivery systems,” he says.

    “While ventilation requirements are well prescribed for some building classes (but not all), the importance of correct ventilation is increased as there can be no reliance on fresh air infiltration via the building fabric. While this is not explicitly included in the design, it can have a meaningful impact in terms of indoor air quality, condensation removal, and potentially mould growth.

    “Direct ventilation, mechanical or natural, increases the required capacity of heating and cooling equipment when outdoor air temperatures, or humidity levels, are outside comfort bands, which is typically most of summer and winter depending on the climate zone.”

    According to Seagren, with efficiencies stated to be between 80-90 percent for high quality heat recovery units, this could allow for a significant reduction in heating and cooling plant capacity, energy consumption, and therefore operational costs.

    An overview of the Passive House Building Standard, high performance building envelopes, airtightness, mechanical ventilation, and construction sequencing were among some of the thought-provoking topics discussed and presented by select industry experts at a Passive House ‘Under Construction’ Workshop hosted by Aurecon and Monash University, and supported by the Australian Passive House Association in Melbourne this April.

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