NatHERS 7-Star Rating: What It Means for Your Melbourne Renovation
In May 2024, new homes and most significant renovations across Australia — including Melbourne — need to meet a 7-star NatHERS rating, up from the previous 6-star minimum. In practice, that means better insulation, better-performing windows, and more deliberate orientation than older homes were built with.
For homeowners renovating an established Melbourne property, this isn't just a box to tick — it can genuinely shape the design. Understanding what's actually being measured, and where the real cost and design impacts sit, makes it much easier to plan for rather than be surprised by.
What NatHERS actually measures
NatHERS (Nationwide House Energy Rating Scheme) models how much heating and cooling energy your home will need, based on its shell — insulation, glazing, orientation, and airtightness. The rating runs from 0 to 10 stars; it does not assess appliances, solar, or hot water systems, which sit under a separate whole-of-home standard introduced alongside the star rating change.
The assessment is done by a qualified accredited assessor using detailed 3D modelling of your design, not a simple checklist — which is why it needs to happen while the design is still adjustable, not after documentation is locked in.
How 7 stars compares to the old 6-star minimum
The step from 6 to 7 stars sounds small on paper but represents a meaningful tightening of the standard — industry estimates put the improvement in thermal performance at roughly 25 to 30 percent. For homeowners, that typically shows up as thicker or higher-performance insulation, upgraded glazing specifications, and considerably more attention paid to draught sealing and airtightness than older builds required.
Why the jump to 7 stars matters
Higher-performance glazing is often required, especially on north and west-facing windows
Wall, floor, and ceiling insulation typically needs to exceed what most 20th-century Melbourne homes have
Orientation and window placement carry more design weight than before — they're now a compliance factor, not just an aesthetic choice
The whole-of-home standard: more than just the star rating
The 7-star NatHERS rating measures your building shell, but it's only half of the compliance picture introduced alongside the star rating change. A separate whole-of-home standard now also applies, covering the fixed equipment that affects a home's total energy use — hot water systems, space heating and cooling equipment, and in most cases, a minimum onsite renewable energy allowance such as solar.
Hot water systems are assessed against efficiency benchmarks, with heat pump and solar systems generally outperforming standard electric or gas storage systems
Heating and cooling equipment efficiency is factored in separately from the building shell's thermal performance
Many councils now expect a home to demonstrate a baseline level of onsite renewable generation, most commonly solar, as part of whole-of-home compliance
Lighting efficiency is also assessed, though it typically has the smallest impact on the overall calculation
This means a renovation can meet the 7-star shell requirement and still need attention paid to equipment selection to satisfy whole-of-home compliance. Discussing both requirements with your architect at the same time, rather than treating equipment selection as a later decision, avoids a compliance gap discovered late in documentation.
Does it apply to every renovation?
Not every project triggers a full 7-star assessment — the threshold depends on the scale of works and how your council and building surveyor classify the renovation. A single room refresh is treated differently to an extension that adds significant new floor area, and alterations to an existing dwelling are assessed differently again to a full rebuild. This is worth confirming early, because it affects both your design brief and your budget.
What it means for your budget and timeline
Higher-spec glazing and insulation typically add cost, but reduce ongoing energy bills
A NatHERS assessment needs to happen at the design stage, not after — retrofitting compliance into a finished design is expensive
Some products (like double or triple glazing) have longer lead times than standard stock, which can affect your build program
Building the assessment into the design process from the start, rather than treating it as a final compliance check, is the difference between a smooth path to approval and a costly redesign partway through documentation.
Frequently asked questions
Do older Melbourne homes need to meet 7 stars for a small renovation?
It depends on the scope — minor internal work is often exempt, but extensions and significant renovations generally aren't.
Can heritage-listed homes be exempt from the 7-star requirement?
Heritage considerations can affect what changes are permitted, but they don't automatically exempt a project — this needs to be confirmed case by case.
Does a higher NatHERS rating cost more to build?
Usually, yes, at the outset — mainly through glazing and insulation — offset over time by lower heating and cooling costs.
Who carries out the NatHERS assessment?
An accredited NatHERS assessor models your design digitally, typically coordinated by your architect during the documentation stage.
Does the whole-of-home standard apply to every renovation that needs a 7-star assessment?
In most cases, yes — where a NatHERS assessment is triggered, the whole-of-home standard generally applies alongside it, though the specific requirements can vary depending on your council and the scale of works.
How does the 7-star requirement interact with the rest of my design brief?
It works best when treated as one of the inputs shaping the brief from the outset, alongside layout, budget, and aesthetic priorities, rather than a compliance step applied afterward. Orientation, window placement, and material choices that satisfy 7-star requirements often align naturally with a good design brief anyway — north-facing living areas and generous glazing tend to be desirable for liveability as much as for compliance, which is one reason the two rarely pull in genuinely opposite directions when they're considered together early. Raising the requirement in your first design conversation, rather than midway through documentation, gives your architect the most room to fold it into the brief without reworking decisions that have already been settled.
If you're planning a renovation and want to understand what 7-star compliance means for your specific home, book a consultation with our team.
Formery Architecture + Interior Design is a Melbourne Architecture studio working across residential renovation, new builds, subdivision and dual occupancy projects. Our director Emma works with homeowners across Melbourne's inner north, inner south-east and bayside suburbs.
Book a free discovery call —formery.com.au