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NatHERS shows up in builder marketing, on contracts, sometimes on listings. What you rarely find is a clear answer to what the rating means for you as a buyer. A guide to stars, the new Whole-of-Home score, certificates, disclosure rules, and due diligence on new and existing homes.
NatHERS shows up in builder marketing, occasionally on a contract, sometimes on a listing. What you rarely find is a clear answer to the question that matters: what does the rating mean for you, the buyer?
Government, energy-assessor, and builder sites cover NatHERS well enough from a compliance angle. They rarely answer the questions a buyer is actually asking: how comfortable will this home be, how cheap to run, how it'll hold up at resale, and whether the rating you've been shown is worth the paper it's printed on.
This guide is the buyer-side version. It explains what a NatHERS rating tells you, what it doesn't, and how to read one during due diligence on both new and existing homes. Melbourne-relevant where the rules diverge, national where they apply. As at May 2026.
NatHERS, the Nationwide House Energy Rating Scheme, is Australia's system for rating the thermal performance of homes. It produces a star rating from 0 to 10, where more stars mean less energy is required to heat and cool the home to stay comfortable. That's the headline figure most buyers see.
Sitting behind it is a software model. An accredited assessor enters plans, climate zone, orientation, glazing, insulation, construction type, shading, and ventilation. The software predicts annual heating and cooling demand. Stars are assigned accordingly.
What the thermal star rating does not measure:
The practical implication: two 7-star homes can have very different real bills and lived comfort, depending on what's been installed, how it's been built, and how it's lived in. The rating is a design-stage signal, not a guarantee of running cost or comfort.
NatHERS now produces two distinct scores, and conflating them is the most common buyer mistake.
Thermal star rating (0 to 10). The classic NatHERS number. Measures how much heating and cooling the building shell needs to keep occupants comfortable. Higher stars equal less mechanical conditioning required.
Whole-of-Home rating (out of 100, can exceed 100). Introduced alongside NCC 2022. Adds the home's appliances (heating, cooling, hot water, lighting, pool and spa pumps, plug-in appliances) and on-site renewables (solar PV, batteries) on top of the thermal shell. A higher score means lower modelled whole-home energy use, once fixed services, plug-in appliances and on-site renewables are accounted for.
The key thing for buyers: solar panels don't add stars. They add Whole-of-Home points. A 6-star home with a strong solar setup and efficient appliances can post a higher Whole-of-Home score than a 7-star home with gas hot water and no solar. Both numbers matter, and they answer different questions.
A buyer-relevant reading of the scale:
The important thing: for new builds and major renovations under the current code, 7 stars is the floor, not the ceiling. A "7-star home" being marketed isn't premium by itself, it's compliant. If you want above-minimum thermal performance, you're looking at 8 stars and up, with the certificate to back it. Existing homes and homes built under earlier code versions sit on different baselines.
This is the split that confuses most buyers, and where the regulator-side content is least useful.
NatHERS is part of the building permit pathway. A rating is done at design stage to demonstrate the home meets the NCC's thermal performance and Whole-of-Home requirements. The certificate is generated, and is typically filed with the building approval. It often doesn't reach the future buyer unless someone asks.
If you're buying off-the-plan or near-new, ask for it. The builder or vendor should be able to produce a NatHERS Certificate showing the thermal star rating, Whole-of-Home score, climate zone, glazing schedule, and insulation assumptions. Match those assumptions to what's actually been built. Substitutions during construction can quietly drop the home below its certified rating.
Until now, NatHERS has had no routine role in established home sales outside the ACT. Most Victorian resale listings have no rating attached, and asking for one rarely produces a meaningful answer. That's changing, slowly.
A national NatHERS for existing homes program was trialled through 2024 and 2025. The trial delivered more than 1,000 free assessments and found the approach viable. Existing-home assessor training began in late January 2026. Stage 2, which is expected to broaden demand and access, follows from mid-2026. An additional data-collector accreditation pathway is expected from late 2026. Until then, assessor capacity is very low, and most established homes you'll consider as a buyer won't have a NatHERS rating you can look up.
A few exceptions worth knowing:
If you want a rating done on an established home you're seriously considering, you can engage an accredited assessor. Published industry pricing varies widely. For a standard detached home, expect several hundred dollars at minimum, commonly around $600 to $800 plus GST, and more for larger or complex homes. Treat very cheap assessments with caution. The industry body has flagged underpricing as a quality risk.
A NatHERS Certificate is more than a star sticker. A well-prepared one will show:
First check: is the certificate accredited? Accredited NatHERS certificates display the NatHERS branding and are issued by an assessor accredited through one of the recognised bodies. Non-accredited reports may look similar but don't carry the same quality controls. If the document doesn't have NatHERS branding and assessor accreditation details, treat it as marketing material rather than a verified rating.
Second check: does the as-built dwelling match the assumptions? Walk the property with the certificate. Check insulation depth where you can see it, window types, shading. A certificate generated at design stage assumes the build matches the plans. If it doesn't, the real rating may be lower than the document suggests.
Third check: does it cover Whole-of-Home? Some older certificates pre-date the Whole-of-Home component. Newer builds should show both numbers. If only the thermal star is shown, ask why.
Three separate questions live inside this one, and they have different answers.
Yes, with caveats. A better-rated home, all else equal, is designed to need less mechanical heating and cooling to stay comfortable. That should translate to lower energy bills, fewer days where the home is uncomfortable, and less reliance on the heating and cooling systems themselves.
The caveat is the gap between modelled and actual performance. NatHERS assumes a standard occupancy pattern. Real households cool more or less, leave doors open, run gas heating in lieu of reverse-cycle, set thermostats unusually high or low. Construction quality and detailing also matter, and aren't tested in the rating. Treat the rating as the home's potential, not its guaranteed running cost.
Limited evidence at the national level, more at the state level. The strongest dataset is from the ACT, where mandatory disclosure under the EER scheme has been in place since 1999. ACT Government reviews have found higher-rated homes sold for modestly more than otherwise equivalent stock, with sale-side disclosure compliance running around 98%.
Translating that to a national NatHERS premium isn't straightforward. ACT EER is a separate 0 to 6 scheme, the disclosure culture is mature, and Canberra buyers are used to factoring it in. In Victoria, where no equivalent disclosure rule currently applies at sale, the resale signal from a NatHERS rating is softer and harder to isolate. The honest answer: it likely supports marketability, particularly to sustainability-conscious buyers, but a clean Australian price premium attributable specifically to NatHERS isn't well established outside the ACT.
Increasingly relevant. Some lenders use NatHERS thresholds as eligibility criteria for green home loan products. Bank Australia's Clean Energy Home Loan, for new builds, currently requires a NatHERS rating of 7.5 stars or higher, alongside all-electric fixed appliances and rooftop solar. Other lenders have their own criteria, often for retrofits rather than purchase. None of this is universal yet. Expect more products tied to ratings as disclosure matures.
The bottom line: a higher NatHERS rating today buys you comfort, lower bills, and some optionality on green finance. Whether it earns a resale premium depends heavily on where you're buying.
Whether you'll see a NatHERS rating on a listing depends entirely on where the property is.
ACT has had a mandatory EER disclosure scheme for residential sales since 1999, with rental disclosure obligations also applying where an EER exists. Sale-side compliance runs around 98%. Rental disclosure compliance is much lower, around 33% in the most recent government review. ACT EER is conceptually similar to NatHERS but legally distinct, and on a different scale (0 to 6 versus 0 to 10). If you're comparing Canberra properties, you're looking at EER, not NatHERS, even if the language sometimes blurs.
NSW began trials of home-energy-rating disclosure from September 2025. A voluntary disclosure phase rolls out from mid-2026, building on what the trial found. A move to mandatory disclosure remains a later step, with timing to be determined.
Victoria does not currently mandate energy-rating disclosure at sale or lease. Two parallel reforms are worth knowing about:
Nationally, the Home Energy Ratings Disclosure Framework Version 2 was agreed by energy ministers in December 2024. It sets the parameters under which states and territories can introduce mandatory disclosure schemes, with NatHERS as the preferred underlying assessment. Translation: expect more jurisdictions to adopt disclosure over the next few years, and expect NatHERS to be the rating most buyers see on listings before the decade is out.
If a listing or builder uses "stars" without specifying which scheme, ask. The number means very different things depending on what's being rated.
The checklist I work through when NatHERS is in play.
Is a 7-star home actually impressive, or is that just the new minimum?
The new minimum. From 1 May 2024 in Victoria, most new residential builds and major renovations must meet 7 stars thermally plus a Whole-of-Home score of at least 60. A 7-star home in 2026 is compliant, not premium. If you want above-minimum thermal performance, look for 8 stars and up, with the certificate to back it.
Does the rating include rooftop solar?
Not the thermal star rating. Solar affects the separate Whole-of-Home score, which sits alongside the star rating on current certificates. If a higher star rating is being attributed to solar, that's a misreading of the certificate.
Will a higher NatHERS rating get me a cheaper home loan?
Sometimes. Bank Australia's Clean Energy Home Loan for new builds currently requires a NatHERS rating of 7.5 stars or higher among its criteria. Other lenders have their own thresholds, often for retrofit lending rather than purchase. Check current criteria with your broker rather than assuming a universal green discount.
Can I get a NatHERS assessment on an established home I'm considering buying?
Yes, but supply is limited. Stage 2 of the existing-homes rollout broadens access from mid-2026 (assessor training started in late January 2026, with a further data-collector pathway expected from late 2026). Before then, you can engage an accredited assessor privately. Published industry pricing varies widely. For a standard home, expect several hundred dollars at minimum, commonly around $600 to $800 plus GST, and more for larger or complex homes. Whether it's worth it depends on the price point and how much the rating is likely to change your view of the property.
Is the NatHERS rating the same as the ACT EER?
No. Different scheme, different scale (0 to 6 versus 0 to 10), different rules. ACT EER is a separate state-legislated scheme with mandatory disclosure at sale and lease. NatHERS is the national thermal and Whole-of-Home rating used for new-home compliance and the emerging existing-home program.
How accurate is NatHERS in real life?
It's a modelled estimate based on standard occupancy assumptions and the building as designed. Real bills depend on how the home was actually built, how heating and cooling are used, your tariff, and your appliances. A high rating predicts the home should perform well thermally. It doesn't guarantee a specific dollar saving.
Will mandatory disclosure of energy ratings become standard at sale?
Probably, on different timelines by state. The national framework agreed in December 2024 sets the parameters for state schemes. The ACT has had it since 1999. NSW is trialling. Victoria has signalled engagement with the framework but no fixed date for sale disclosure. Expect the picture to shift through the second half of the decade.
What's Whole-of-Home, and why does it matter?
A separate NatHERS score introduced with NCC 2022. It models the home's total energy use across heating, cooling, hot water, lighting, pool and spa pumps and plug-in appliances, netted against on-site renewables (solar PV, batteries). Score out of 100, can exceed 100. Reads alongside the thermal star rating, not instead of it. The two answer different questions: stars are about how comfortable the shell is, Whole-of-Home is about how cheaply the fitted services and appliances run.
How much does a NatHERS assessment cost?
Published industry pricing varies widely. For a standard detached home, expect several hundred dollars at minimum, commonly around $600 to $800 plus GST, and more for larger or complex homes. There's no nationally fixed fee. Treat very cheap assessments with caution. Cost varies by assessor experience, property complexity, and whether Whole-of-Home is included.
When a NatHERS rating is on the table, I treat it as one signal in a broader read of the home, not the deciding factor. For new builds, the certificate is a starting point for due diligence on what's actually been built. For existing homes, the absence of a rating is the more common situation, and the thermal due diligence is done by eye and by spec sheet rather than by document.
The signal I'm reading is consistency. A genuinely well-performing home has a rating that holds up when the as-built fabric is checked, a Whole-of-Home score that reflects sensible appliance and solar choices, and an assessor whose accreditation can be verified. Marketing-only "star" claims, certificates that don't match the dwelling, and "6-star" marketing where 7 is now the minimum are flags worth registering.
If you're buying in Melbourne over the next two years, the best use of NatHERS is as a baseline. Use the certificate to ask sharper questions. Don't expect it to answer them all.
If you'd like a second set of eyes on a specific property's rating, or on the thermal due diligence for an unrated established home, get in touch.
If you’d like to talk it through, we can map out the next step.
No obligation. Just context.
It all starts with a confidential conversation.
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