“Passive House (PH), or in the original German Passivhaus, denotes a highly energy-efficient building, one that can be conditioned passively without much, if any, fossil fuel use, and is gaining popularity as a brand across Australia”
The challenges for the future-fit of Passive House in Australian housing lie in addressing new ways of living from domestic, demographic, sustainable, and affordable perspectives. Making a Passive House “future-fit” means ensuring the super energy efficient buildings remain comfortable, climate resilient, and cost effective as climate conditions shift and building regulations evolve.
The primary challenges lie in managing summer overheating, scaling up complex supply chains, and transitioning to sustainable, low-carbon materials.
Most participants in the recent debate event supported Passive House’s role in future housing provision. The standard provides a framework for linking energy efficiency and comfort. From an engineering perspective, the standard indicates that the Australian Building Code is moving toward a fabric first approach with improved airtightness, insulation, and mechanical systems for climate control. From a construction perspective, the certification process is viewed as a major advantage, providing clear aims, processes, and outcomes.
Additional comments
Whilst agreeing with Passive House’s aims, there was much discussion about the means of achieving them. Participants made several observations about the future fit.
- Passive House is a misnomer; it is designed around mechanical principles. The fabric remains constant, and the active systems are adapted to different climates. But the fabric, which is passive and fixed, remains the main source of thermal comfort while the active system is minimal as a consequence, so can this be described as passive
- In contrast to passive climate-responsive design, there is a significant overreliance on mechanical systems. The fabric is adapted to a site and climate, and active systems are minimised. The former is deterministic while the latter is indeterminant, transactional. Future fit will necessitate blending the two approaches.
- Passive House sees this as a design problem as part of the design phase, not a systems problem. Questions about the design’s validation and the performance gap with operations are of concern. For example, a recently built 7-star rated NatHERS building with high energy efficiency, reported IEQ, and condensation, as the occupants could not afford to heat the building. Both Passive House and NatHERS should consider more education, better briefing, commissioning, and affordability criteria need to be added to the energy standards to meet occupant expectations.
- Overheating in Passive Houses has been studied in depth. Super insulation may mitigate underheating in cold climates, but it may cause excessive overheating and increased energy use during hot periods in all climates, particularly room by room. Passive Houses with sufficient natural ventilation can apply the Adaptive model of thermal comfort.
- PHPP (Passive House planning package) modelling uses a steady state calculation method. A computer simulation has now replaced this system. From a modelling perspective, extreme airtightness (Maximum Limit: ? 0.6 Air Changes per Hour at 50 Pascals [ACH50]) is not necessary; 0.4 is sufficient in Australian conditions. Furthermore, using future climate files in the modelling process reduces uncertainty and improves the reliability of the estimation.
- A Brisbane project home builder has been found to use the Passive House concept for subtropical design. With growing interest in this approach, it’s crucial to examine the science behind it to validate its credibility. If their methods diverge from established Passive House standards, it could mislead consumers regarding energy performance. Clarifying whether their approach aligns with Passive House principles is essential for ensuring customers understand their homes’ energy efficiency and design. Analysing the science of Passive House in subtropical settings can help validate or challenge their claims.
- The standard would better encourage the use of mixed-mode operational practice, identifying free-running periods and adding operational guidance. Mixed-mode operational practice combines manual and automatic controls for managing indoor conditions, enhancing comfort and energy efficiency. Free-running periods are periods when a building can remain comfortable without mechanical heating or cooling, enabling energy savings. Operational guidance involves offering best practices for building managers and occupants on how to effectively use mixed-mode systems, such as when to ventilate naturally.
Overall, these questions about the Passive House standard suggest a re-evaluation of its sufficiency and stringency in addressing future housing needs, including a focus on retrofitting existing buildings. More research is needed on the value proposition of Passive House for Australia, and its future fit should be reconsidered. Its value proposition is based on an energy efficiency approach that emphasises thermal comfort and indoor air quality at a cost premium.
Some argue that the value of the proposition could be improved by leveraging the affordability of solar energy and a passive design approach. Greater self-sufficiency and reduced greenhouse gas emissions can be traded against energy efficiency technologies, saving resources, capital, and operational costs.
Finally, a study by Duc Minh Le, et al. evaluates climate resilient retrofit strategies for existing Australian homes, using projected 2050s weather data under future moderate (RCP4.5) and high-emission (RCP8.5) scenarios.
They summarise that a brute force parametric analysis was employed, simulating 120,960 unique retrofit combinations (envelope insulation, exterior colour, fenestration upgrade, and ceiling fan application) for a representative building archetype. The assessment covered annual heating/cooling energy consumption and thermal resilience, a home’s ability to maintain safe conditions during extreme events, across four distinct climate zones (Brisbane, Canberra, Melbourne, and Sydney).
Results show a climate driven shift in retrofit priorities and achievable benchmarks; for example, a current 7-star NatHERS building will be a 5 Star building.
The researchers analysed weather patterns based on predictions for the 2050s using two scenarios. The first is the moderate emission scenario, in which global emissions peak around 2040 and then decline, resulting in moderate climate change. The second is the high emission scenario, which assumes emissions rise significantly without any actions taken, resulting in severe climate change.
In climate modelling, these pathways describe different levels of greenhouse gas concentrations and the amount of heat trapped in the atmosphere by the year 2100
Conversely, in cooler climates (Canberra, Melbourne), reduced winter demand initially improves annual performance (more than 30 per cent heating reduction), before it reaches a turning point at which future cooling loads rise and negate these benefits.
Thus, the configuration of an optimised retrofit design is not static but must evolve in response to climate change. While a highly insulated and airtight building envelope improves annual energy performance, it can pose severe overheating risks during power outages.
However, pairing this high-performance envelope with adaptive strategies (natural ventilation) proves transformative, significantly enhancing passive survivability during future heatwaves. Ultimately, a holistic, systems-based approach that integrates passive measures and adaptive strategies is essential to ensure that retrofitted homes are not only energy-efficient year-round but also safe and climate-resilient in the face of extreme future conditions.
References
- Clark, J. (2011). Housing Futures, Architecture Australia, May June. https://architectureau.com/articles/housing-futures/
- Happy Haus. (2026). https://happyhaus.com.au.
- Wall, C., & Hyde, R. (2026). Passive House (Passive Haus): The Value Proposition Australia. Frith coming.
- Hyde, R., Wadley, D., & Hyde, J. (2025). Household Challenges in Solar Retrofitting to Optimize Energy Usage in Subtropical Climates. Energies, 18(23), 6312. https://www.mdpi.com/1996-1073/18/23/6312
- James, M. & Brill, J., 2016, Passive House in Different Climates. The Path to Net Zero, 1st Edition, Routledge. file:///Users/richardhyde/Downloads/10.4324_9781315696553_previewpdf.pdf
- McLeod, R. S., Hopfe, C. J., & Kwan, A. (2013). An investigation into future performance and overheating risks in Passivhaus dwellings. Building and Environment, 70, 189–209. https://www.sciencedirect.com/science/article/abs/pii/S0360132313002503
- Mitchell, R., & Natarajan, S. (2019). Overheating risk in Passivhaus dwellings. Building Services Engineering Research and Technology, 40(4), 446-469.https://journals.sagepub.com/doi/full/10.1177/1420326X231153856
- Le, D. M., Christopher, P., & Ngo, T. (2025). Climate-Resilient Retrofitting for Australian Homes: A Parametric Analysis of Future Performance and Overheating Risk. Results in Engineering, 108176. https://www.sciencedirect.com/science/article/pii/S2590123025042227
- Pitts, A. (2017). Passive House and Low Energy Buildings: Barriers and Opportunities for Future Development within UK Practice. Sustainability, 9(2), 272. https://doi.org/10.3390/su9020272. https://www.mdpi.com/2071-1050/9/2/272
- Ren, Z., Tang, Z., & James, M. (2021). Predictive weather files for building energy modelling. https://ahd.csiro.au/wp-content/uploads/Predictive-weather-files-User-Guide.pdf
- Rupp, R. F., Kim, J., Toftum, J., Brager, G., & de Dear, R. (2025). Ten questions concerning the application of adaptive thermal comfort in mixed-mode buildings: Building and Environment, 113490. https://backend.orbit.dtu.dk/ws/portalfiles/portal/408974496/1-s2.0-S0360132325009631-main.pdf
- Welch, S., Obonyo, E., & Memari, A. M. (2023). A review of the previous and current challenges of passive House retrofits. Building and Environment, 245, 110938. https://www.sciencedirect.com/science/article/abs/pii/S0360132323009654
Acknowledgments
Lyndsay Clare and Kerry Clare
