The short answer
Under NCC 2025, most new houses taking the NatHERS route must reach 7 stars, the same minimum as NCC 2022. In climate zones 1 and 2 it can be 6.5 or 6 stars where the house has a qualifying roofed outdoor living area. Glazing has its own checks: conductance in climate zones 2 to 8 and solar heat gain in climate zones 1 to 7. Victoria adopted NCC 2025 on 1 May 2026.
What does 7 stars actually measure?
It is a thermal rating, scored out of 10 stars, for the heating and cooling energy a home needs to stay comfortable. It says nothing about your appliances. That is the second number: the Whole of Home rating, scored out of 100, which covers heating, cooling, hot water, lighting, cooking and pool pumps, less anything solar puts back. On the NatHERS route, the Whole of Home figure has to be not less than 60.
Minimum NatHERS thermal rating
Show the numbers
| Item | Range |
|---|---|
| Most new houses | 7.0 NatHERS stars, out of 10 |
| Climate zones 1 and 2, with conditions | 6.0 to 6.5 NatHERS stars, out of 10 |
What changed with NCC 2025?
For a house, less than the headline suggests. The star minimums and the Whole of Home figure above read the same in NCC 2025 as they did in NCC 2022, and the glazing clauses in Part 13.3 still split the work between a conductance check and a solar heat gain check. Victoria adopted the new edition on 1 May 2026. Which edition applies to a project that was already in design or underway is a question for your building surveyor, not a brochure.
Where do windows come into it?
Glazing is the weakest part of most walls, which is why it carries its own provisions. YourHome puts the loss at up to 40% of a home's heating energy, and the gain at up to 87%. A designer trades window size, orientation and performance against each other to land the rating, and the ABCB publishes a free NCC 2025 Housing Energy Efficiency Calculator for working the deemed-to-satisfy version through.
Is it true that the tropical north has no glazing rules?
No, and this one travels a long way. It's true that the conductance clause does not apply in zone 1, because there is little or no need for heating there, and that's where the myth starts: the conductance check covers climate zones 2 to 8 only. But the solar heat gain limit still applies there, because it runs across climate zones 1 to 7. If anything, zone 1 is where keeping the sun out of the glass matters most. Zone 8 is the one left out of the solar heat gain check.
Do the 7-star rules apply when you replace windows?
The star minimum is written for new homes, so a straight window swap in an existing house is not rated against it. That is not the whole story in Victoria. The building regulator says full replacement of building elements is treated as an alteration, and its guidance is that extending or substantially renovating a home, more than 50 per cent of it, may bring the current energy requirements into play. A registered building surveyor is the person who decides where your job sits.
How do you find your climate zone?
The ABCB publishes a climate zone map you can search by address or postcode. Melbourne, for example, is in climate zone 6, where summer cooling and winter heating both count, so a window choice that is right for Brisbane can be wrong there.
This is a summary of published provisions, not a compliance check. For a building permit, the numbers come from a NatHERS assessor and a registered building surveyor.