On 1 July 2026 the Nationwide House Energy Rating Scheme opened the second stage of its expansion to existing homes, a year after the first. An accredited assessor can now walk through any established Australian house, measure what is actually there, and issue a certificate of its own. Behind it sits a national field trial run with the CSIRO from 2024 to early 2026, which delivered more than 1,000 free assessments across a range of climates and dwellings and concluded the scheme was viable, fit for purpose and should be fully implemented.
Running costs did not vanish with the rate cycle. The Australian Energy Regulator's 2026-27 default market offer cut residential flat-rate prices from 1 July 2026, by 3.4% in the Ausgrid and Endeavour zones and 5.0% in the Essential Energy zone in New South Wales, and by 7.2% in south-east Queensland, yet the AER still prices the flat-rate default offer in the Essential Energy zone at $2,604 a year on 4,600 kWh, and the building sets a large share of that bill for as long as you own it. This guide covers the 7-star rule, what a rating measures, how to check one, the premium evidence, retrofit costs and the finance that helps. It belongs on your checklist next to the pest report and the insurance quote.
The 7-star rule, state by state
Building Ministers agreed in August 2022 to raise the minimum, and the National Construction Code 2022 lifted the thermal rating for new houses to the equivalent of 7 NatHERS stars out of 10, adding a whole-of-home energy budget for fixed appliances. Each state chooses when, and whether, to adopt it. NCC 2025, published on 1 May 2026, tightened energy efficiency for commercial buildings and left the residential requirement where NCC 2022 put it, so 7 stars is still the number for new homes.
The commencement dates below come from the Australian Building Codes Board's own adoption tables, which is where to check them if you are buying a home approved close to one of these dates.
| Jurisdiction | 7-star commencement | Applies to | Status at September 2026 |
|---|---|---|---|
| NSW | 1 October 2023, through enhanced BASIX | New homes, except climate zones 9, 10 and 11 in north-eastern NSW and apartment buildings up to 5 storeys | In force; a transition for contracts signed before that date ended 30 September 2024 |
| ACT | 15 January 2024 | New houses and apartments | In force; the only jurisdiction with mandatory rating disclosure at sale |
| Victoria | 1 May 2024 | New homes and apartments | In force |
| Queensland | 1 May 2024 | New houses and units, with an optional outdoor living area credit | In force |
| South Australia | 1 October 2024 | New homes and apartments | In force |
| Western Australia | 1 May 2025 | New homes and apartments | In force |
| Tasmania | Not adopted | Minimum stays at 6 stars | Tasmania adopted NCC 2025 on 1 May 2026 but replaces its energy efficiency part with the 2019 code's, which sets 6 stars |
| Northern Territory | Not adopted | Minimum stays at 5 stars | The NT variation caps the requirement at 5 stars and the NT has not adopted NCC 2025 |
A house completed in Hobart or Darwin in 2026 is therefore not a 7-star house unless the builder chose to exceed the code. Everywhere else, 7 stars is the floor the certifier holds the builder to, and a certificate issued on the plans is only as good as the company that finishes the build, one more reason builder due diligence matters.
What a rating actually measures
A NatHERS certificate now carries two numbers, and buyers routinely confuse them.
The Star Rating (0 to 10) measures the building shell only: orientation, insulation, glazing, shading, thermal mass and air leakage, run against the local climate file. It estimates how much heating and cooling the house needs to stay comfortable; appliances do not count. A 7-star home, in the scheme's own words, needs only a small amount of heating and cooling.
The Home Energy Rating (0 to 100+), called whole-of-home for new builds, adds fixed appliances (heating, cooling, hot water, lighting, pool and spa pumps) and any solar or battery, and estimates annual energy use and cost. A score of 100 means net zero over the year, and a home that exports more than it uses can rate above it. Under the code a new house must reach 60 and a new apartment 50, nationally, not just in one state.
The gap between 6 and 7 stars is larger than one digit suggests. Sustainability Victoria says that in most locations a 7-star home needs 20% to 25% less heating and cooling energy than a 6-star one; RMIT researchers writing for The Conversation and republished by CSIRO's Australian Housing Data put the cut at about 24%. The NSW Planning Portal says the higher BASIX standards, which lifted the state from an average of 5.5 to 6 stars to 7, could save as much as $980 a year on energy bills. The same RMIT analysis put the extra capital cost of reaching 7 stars at an average $1,704 across detached houses and townhouses, ranging from $545 in Queensland to $3,275 in the Northern Territory, or 0.1% to 0.8% of total capital cost. Builders often quote a higher number, so ask what is actually in it.
How to check a rating on an established home in 2026
There are two routes, and one that has just closed.
Ask for the certificate. Any home built to 7 stars has a new-home certificate dated after its state's commencement date. Ask the agent for it and scan the QR code, which links to a secure online record. The ACT is the only jurisdiction where a seller must disclose the rating, so outside Canberra this is a request, not an entitlement.
Commission a NatHERS existing-home assessment. An accredited assessor visits for two to three hours, records the building fabric, air leakage, appliances and solar, then models the home in accredited software. You get the Star Rating, the Home Energy Rating, estimated annual energy use and a list of upgrade options. Assessors set their own fees, so the scheme's advice is to contact more than one for a quote, and NSW is offering subsidised assessments to eligible households in a pilot running in limited locations. The "Find an Assessor" tool on homeenergyrating.gov.au lists assessors by postcode. An existing-home certificate cannot be used for building-code compliance, so a major renovation still needs a new-homes assessment.
An old Residential Efficiency Scorecard. The Scorecard ran from 2017 as a national program administered by the Victorian Government, and its own website confirms it has now closed, with households pointed to the NatHERS expansion instead. You cannot commission one any more. If a vendor produces an old Scorecard certificate it still tells you something, but it rated the cost of running the home's fixed appliances out of 10 stars, not the building shell, so it is not a NatHERS certificate and the two scales are not interchangeable.
When there is no certificate, ask the vendor for the year built, the ceiling insulation and its R-value, the window type, the hot water system's age, and the solar system's size, inverter age and warranty, and have the building inspector photograph the ceiling space.
Disclosure when you sell. Not compulsory yet, outside the ACT. Energy Ministers released Version 2 of the national Home Energy Ratings Disclosure Framework in December 2024, but it leaves the rules to each state and territory. NSW and the Commonwealth ran a trial of disclosure at sale and lease, and the scheme says the findings will inform when NSW moves to mandatory disclosure. No date has been set, and no other state has legislated.
What buyers pay for efficiency
The headline number comes from Domain's Sustainability in Property Report 2025, published on 29 May 2025. Houses whose listings advertised energy-efficient features sold for 14.5% more than those that did not, a median gap of $118,000 nationally, rising to 23.8% and $197,000 in Melbourne. Listings mentioning solar carried a $140,000 gap, double glazing $145,000 and a north-facing aspect $375,500.
Read those with care, for three reasons. Domain's own methodology note says it separates efficient from non-efficient homes using keyword data in for-sale and sold listings, then compares medians. Nothing holds size, land, location or age constant, so the figures do not separate the feature from the kind of house that has it. Solar and double glazing cluster in newer, larger homes, and a north-facing aspect is as much a location premium as an efficiency one. Second, the premium is shrinking rather than growing: it peaked at 17.2% and $125,250 in 2022. Third, some of the feature numbers rest on very little. Double glazing appeared in only 1.8% of listings, five of the eight capitals produced no double-glazing figure at all, and Canberra's north-facing premium came out at minus $250. The $140,000 gap for solar is not what a solar array adds to a house; it is the gap between the houses that have solar and the houses that do not.
The rating-based evidence is older and narrower, because only the ACT has had ratings on every sale. A 2008 study the Australian Bureau of Statistics prepared for the federal environment department modelled Canberra sales and found that a 1-star improvement lifted market value by about 3% on average, 2.5% on 2005 sales and 3.8% on 2006, holding floor area, block area, distance to the city and neighbourhood advantage constant. Modelled a second way, as rating bands rather than a straight line, the premium kept rising with the rating but the marginal addition to it declined. Note the base: 2,385 Canberra sales in 2005 and 2,719 in 2006, detached houses only, with anything built after the ACT's own 1995 rating scheme excluded. It is the best Australian evidence there is on ratings and price, and it is twenty years old. A December 2024 paper by Exemplary Energy, looking at advertised asking prices rather than settled sales, found that correlation had become weak at best, with an inverse relationship across all dwellings together that has persisted since late 2014. The authors put that down to the worst-rated properties sitting closest to the city centre where land is dearest, and to apartments rating well but selling for less than houses while taking a growing share of the market. Split by dwelling type, the premium reappeared, and most starkly for apartments: in most ACT suburb regions, the paper says, a higher-rated apartment would almost certainly attract a price premium.
In short, the evidence that efficiency itself commands a premium is thinner than the headline numbers suggest. Homes advertised as efficient do sell for more, but no Australian work since 2008 has isolated the rating from the size, age, land and aspect that travel with it, and the one recent ACT analysis found the raw relationship running the other way. The first Australian study using existing-home NatHERS certificates cannot exist yet, because those certificates have only existed since 2025. The wider case for energy efficiency as a value driver, including insurance and climate exposure, is covered separately.
The cost to retrofit an older home
If the house you want rates 2 or 3 stars, the question is what it costs to move it. No government source publishes retrofit prices, so every figure below comes from a commercial price index. They are a starting point for your own quotes, not a substitute for them.
| Upgrade | Indicative installed cost, 2026 | What it does | Source |
|---|---|---|---|
| Ceiling insulation, 3-bedroom house | $800 to $2,500 ($12 to $35 per square metre) | Biggest thermal gain in an uninsulated home. the 2008 ABS study found R4 ceiling batts, then costing about $1,200, lifted a poorly insulated home by at least one star | What's The Damage, September 2026 |
| Heat pump hot water | $4,635 national average after STCs, $4,827 in NSW | Runs on about $150 to $300 a year on Solar Choice's modelling against $450 to $900 for resistive electric; the saving depends on your tariff and household size, so work the payback for your own home | Solar Choice price index, 1 September 2026 |
| Rooftop solar, 6 kW | $6,390 national average after STCs; 10 kW $9,870 | Lifts the Home Energy Rating; does nothing for the Star Rating. City averages vary widely, from about $5,070 in Perth to $9,890 in Darwin on a 6 kW system | Solar Choice price index, 1 September 2026 |
| Home battery, 10 kWh | $9,584 average installed after the federal discount, battery only; $10,384 with a new inverter | Shifts solar into the evening peak. The discount is paid in certificates calculated on usable, not nominal, capacity, so a battery sold as 10 kWh earns less than 10 kWh worth | Solar Choice battery price index, August 2026; Clean Energy Regulator, February 2026 |
| Double glazing, whole house (10 to 14 openings) | $10,000 to $28,000; retrofit units into sound frames $550 to $1,100 a window; secondary glazing $400 to $850 | Largest Star Rating lever after insulation, and the easiest place to over-spend | Going Rate, June 2026 |
| NatHERS existing-home assessment | Quoted by the assessor, so get more than one | Tells you which of the above the house actually needs | Home Energy Rating, June 2026 |
Order matters. Draught sealing and ceiling insulation cost the least and move the Star Rating the most; glazing is expensive and should target the rooms you occupy at the temperature extremes. Households that financed upgrades through the federal Household Energy Upgrades Fund are estimated to save an average of $1,700 to $2,300 a year on their energy bills, on Clean Energy Finance Corporation analysis and CSIRO modelling using data to October 2025, published by energy.gov.au in August 2026.
A new granny flat is a new Class 1 building and must meet the current standard in adopting states, so its rating will often beat the main house.
Green loans and rebates in 2026
The finance side has thinned at the big banks and thickened at the smaller ones. The rates below were advertised on each lender's own site on 7 September 2026 and they move, so confirm the rate and the eligibility rules before you apply.
| Program | What it offers | Conditions |
|---|---|---|
| Bank Australia Clean Energy Home Loan | 5.88% p.a. variable for a qualifying new build and 5.98% for a renovated established home, comparison rates 6.21% and 6.25% | Owner occupiers and investors, principal and interest, LVR up to 90%, $199 a year. The reduced variable rate runs 60 months from settlement, or the term of a 3-year fixed, then reverts. A property can qualify only once, so check whether a previous owner already used it |
| Gateway Bank Green Plus Home Loan | 5.85% p.a. variable, 6.14% comparison rate | Needs a property rated 7 NatHERS stars or higher. The rate sits on the package tier for LVR up to 80%, so budget for a 20% deposit, and $299 a year |
| CommBank | No green home loan appeared on its home loan pages on 7 September 2026 | It is one of the seven Household Energy Upgrades Fund lenders, so ask about that instead |
| Household Energy Upgrades Fund (federal, $1 billion) | Discounted loans for solar, batteries, insulation, glazing, heat pumps and appliances through seven lenders: Plenti, Westpac, ING, Bank Australia, CommBank, Brighte and Plico | Existing homes; more than 10,000 upgrades across about 4,100 homes by the December 2025 quarter. One lender's discount is fully drawn, so check what each is still offering |
| Cheaper Home Batteries Program (federal) | Around 30% off an eligible battery, from 1 July 2025 | Must pair with rooftop solar. Since 1 May 2026 the certificates are tiered by size (full rate to 14 kWh, 60% from 14 to 28 kWh, 15% from 28 to 50 kWh) and the certificate rate now steps down every six months to hold the discount near 30% as battery prices fall; expanded to an estimated $7.2 billion on 13 December 2025 |
Two notes for investors. Victoria's minimum energy efficiency standards for rentals phase in from 1 March 2027: ceiling insulation, efficient cooling and 4-star shower heads when a new rental agreement starts, which includes a fixed term rolling over to month to month, plus efficient electric heating and an efficient water heater when the old unit fails beyond repair, and draughtproofing from 1 July 2027. Cooling then applies to every rental from 1 July 2030 whatever the lease. A cheap Melbourne rental with an empty ceiling space carries a compliance bill, so read the regulations before you price the deal. And a green mortgage discount is worth more than most rebates over 30 years, so ask a mortgage broker which lenders accept your certificate before you settle.
The risks
Greenwashing in listings. "Energy efficient" costs nothing to type. Since July 2026 the answer is "show me the certificate", and a genuine one has a QR code to an online record.
Ratings on plans versus as-built. A new-home certificate models the design. Insulation left out around downlights or a glazing substitution during construction will not show on the paper. When buying off the plan, ask for evidence the as-built inspection matched the certificate, or commission an existing-home assessment after completion.
Over-capitalising. The ABS study found the gain per star shrinks as ratings rise, and in its banded model the 4-star group carried a slightly larger premium than the 5 and 6 star group above it. Whole-house double glazing at $28,000 on a home the market will value at 6 stars either way is a comfort purchase, not an investment.
Frequently asked questions
Does a 7-star home cost more to build?
Marginally. RMIT researchers put the average extra cost at $1,704 across detached houses and townhouses and $2,051 for apartments, between 0.1% and 0.8% of total capital cost, and expected bill savings to outweigh the extra repayments in many circumstances, though they noted that in some places, Brisbane and Sydney among them, the move to 7 stars may not be cost-effective on their conservative assumptions. Orientation is the cheapest lever, because putting the living areas on the northern side costs nothing at the design stage.
Will an energy rating be compulsory when I sell?
Only in the ACT today, the one jurisdiction with a mandatory disclosure scheme. Energy Ministers released the national framework in December 2024, NSW and the Commonwealth have trialled disclosure at sale and lease with mandatory disclosure to follow at a date still to be set, and the other states have not legislated. Expect it within the life of a normal ownership, not within your current contract.
Is a solar system worth more on resale?
Buyers pay more for homes with solar, but Domain's $140,000 figure is a gap between two kinds of house, not the value of the panels. A 6 kW system averaged $6,390 installed nationally in September 2026, and an ageing inverter is a replacement item. Treat solar as a running-cost benefit and a tiebreaker, and check size, age and warranty.
What to do now
Ask every agent for the NatHERS or BASIX certificate before the second inspection. If there is none and the home is on your shortlist, book an existing-home assessment and treat the assessor's fee as part of the due diligence budget. Use the certificate's upgrade list to price the cheap items (insulation, draught sealing, hot water) into your offer rather than paying an "energy efficient" premium for a solar array on an uninsulated house.
If you are buying new, check the approval date against the state's 7-star commencement date and ask for as-built evidence. A buyer's agent who does this every week will already know which builders' certificates match the finished product; GoMatch will match you with one for free.
All figures were checked against the sources below on 7 September 2026; loan rates, rebates and the NSW disclosure timetable are the items most likely to have moved.
Sources
- Home Energy Rating (NatHERS), "Measuring the energy efficiency of existing homes", "How to get an assessment", "Understanding your certificate", "Improving your rating" and "Disclosure", homeenergyrating.gov.au. Updated 23 and 24 June 2026.
- Home Energy Rating, "Stage 2 of Home Energy Rating for existing homes begins" and "NatHERS for existing homes trial report". 1 July 2026.
- Home Energy Rating, "Promoting home energy ratings and disclosure". 26 August 2026.
- Australian Energy Regulator, "Information Kit, Default Market Offer 2026-27". May 2026.
- Australian Building Codes Board, "NCC 2022 state and territory adoption dates" (correct as at 22 September 2023) and "NCC 2025 state and territory adoption information", ncc.abcb.gov.au.
- Australian Building Codes Board, National Construction Code 2025 Volume Two, Specification 42, Schedule 9 Tasmania and the Northern Territory schedule. Published 1 May 2026.
- Australian Building Codes Board, National Construction Code 2019 Volume Two Amendment 1, clause 3.12.0.1.
- NSW Planning Portal, "BASIX" and "Increase to BASIX Standards". Commenced 1 October 2023.
- Business Queensland, "Whole of Home assessment and score" and "7-star energy standard for units", business.qld.gov.au.
- ACT Government Planning, "National Construction Code (NCC)", planning.act.gov.au.
- Department of Climate Change, Energy, the Environment and Water, "Residential buildings", dcceew.gov.au. Updated 23 February 2026.
- Sustainability Victoria, "Seeing 7-stars: new home energy efficiency standards explained".
- Moore, T. and Willand, N. (RMIT University), "Will 7-star housing really cost more? It depends, but you can keep costs down in a few simple ways", The Conversation, republished by CSIRO Australian Housing Data. 16 September 2022.
- Domain, "Sustainability in Property Report 2025". 29 May 2025.
- Australian Bureau of Statistics for the Department of the Environment, Water, Heritage and the Arts, "Energy Efficiency Rating and House Price in the ACT". 2008.
- Lee, T., Grounds, V. and Paterson, L. (Exemplary Energy), "Energy Efficiency Rating of Dwellings, Effects on ACT Sale Prices and Building Stock", Asia Pacific Solar Research Conference. 3 to 5 December 2024.
- What's The Damage, "Insulation Cost Australia 2026". Verified September 2026.
- Solar Choice, "Heat Pump Hot Water Price Index" and "Solar Choice Price Index" (both 1 September 2026), and "Battery Price Index" (August 2026).
- Going Rate, "Double Glazing Cost Calculator (Australia 2026)". Pricing reviewed June 2026.
- Residential Efficiency Scorecard, homescorecard.gov.au, program closure notice. Archived 8 July 2026.
- Clean Energy Regulator, "Changes to rebate for solar batteries from 1 May". 17 February 2026.
- energy.gov.au, "Cheaper Home Batteries Program".
- energy.gov.au, "HEUF households saving up to 80% on energy bills". 13 August 2026.
- energy.gov.au, "Household Energy Upgrades Fund reaches 10,000 installations". 29 April 2026.
- Bank Australia, "Clean Energy Home Loan", bankaust.com.au. Accessed 7 September 2026.
- Gateway Bank, "Green Plus Home Loan". Accessed 7 September 2026.
- Commonwealth Bank, home loan pages, commbank.com.au. Accessed 7 September 2026.
- Consumer Affairs Victoria, "New minimum energy efficiency standards" for rental properties, and the Residential Tenancies Amendment (Minimum Energy Efficiency Standards) Regulations 2025. Commencing 1 March 2027.
