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In Australia, the 7-Star NatHERS standard has raised the bar for energy efficiency, a welcome step in the right direction. But for homeowners chasing true comfort and predictable performance, the Passivehaus (Passive House) standard pushes things much further.
To see what this means in practice, the Australian Passivhaus Association (APA) recently ran the Passivhaus Incubator project, in which the participants modelled how the same home design would perform as a 7-Star NatHERS house versus a certified Passive House across different Australian climates. Today the results were presented by Joel Seagren at Brickworks Design Studio in Melbourne, and offer one a clear comparison between the two approaches.
NatHERS 7-Star is a relative rating system (based on MJ/m²/yr) predicting thermal comfort and energy use compared to a benchmark.
Passive House is an absolute performance standard (in kWh/m²/yr), verified through airtightness testing, PHPP energy modelling, and on-site commissioning.
Envelope & detailing: Passive House construction focuses on airtightness, continuous insulation, triple glazing, and elimination of thermal bridges.
Ventilation: Passive Houses use mechanical ventilation with heat recovery (MVHR), ensuring fresh filtered air without energy loss.
Comfort: Every room stays at an even temperature — no drafts, no cold spots, no overheating.
The most dramatic difference, however, is in energy demand for heating and cooling.
At the Passivhaus Incubator program, a reference home was modelled across Melbourne, Canberra, and Sydney. The data compares the 7-Star NatHERS design to the same house upgraded to meet Passive House criteria.
Here's some data shown during the presentation that relates to the modelling of a "standard" passive solar design (CSIRO “SAP 300 Design”):
| City | Energy Demand (kWh/m²/yr) | 7-Star | Passive House | Reduction |
|---|---|---|---|---|
| Melbourne | Heating | 89.4 | 12.9 | 86 % |
| Cooling | 10.0 | 3.6 | 64 % | |
| Canberra | Heating | 122.5 | 13.0 | 89 % |
| Cooling | 4.8 | 0.8 | 83 % | |
| Sydney | Heating | 32.7 | 4.0 | 88 % |
| Cooling | 23.0 | 12.7 | 45 % |
(Source: Australian Passivhaus Association – Passivhaus Incubator presentation, 2025)
Across all climates, the Passive House model slashed heating energy by 85–90 %, while cooling energy dropped by 45–80 %, depending on location. Even in mild Sydney, where cooling loads dominate, the Passive House achieved nearly half the energy demand of the 7-Star home, all without compromising comfort.
These results confirm similar findings from previous research (e.g. AIRAH’s Ecolibrium journal, 2019), showing that airtight, thermally bridge-free construction and controlled ventilation can reduce energy demand by 60–80 % compared to high-performing but conventionally built homes.
While both standards create energy-efficient homes, Passive House achieves:
Measured airtightness (≤ 0.6 ACH@50 Pa, blower-door tested)
Verified comfort (temperatures between 20–25 °C year-round)
Healthier air quality, thanks to MVHR filtration and humidity control
Predictable performance, not dependent on occupant behaviour
In short: a 7-Star home is good, a Passive House is proven.
At TERRA!, we believe that great architecture should not just look beautiful, it should perform beautifully. That means we don’t settle for the bare minimum.
When we design a home, we often start with a 7-star baseline as a good step up from code, but we also evaluate what it would take, in insulation, detailing, orientation, and services, to push that same design into Passive House territory. That way, you (the client) can see what the trade-offs are: additional upfront cost, different detailing, perhaps a little more coordination in construction, versus dramatically lower energy bills, better comfort, and a more resilient home.
If you’re curious, we can even generate a “dual path” energy model for your future home: one to a 7-star standard, and one to Passive House. You’ll see exactly where the biggest gains come from, what the cost delta might be, and whether going all the way is a smart investment.
Ready to explore? If you’d like us to run that comparative model for your project, or talk through how your next design might be upgraded, just get in touch, we’d love to walk you through it.