Self powering homes are being pitched as the next step for Australian housing. The rating tool that measures them is already sitting on every new build certificate, and most builders have never looked at the number.
Last updated: August 2026
A home that generates more energy than it consumes is not a prototype. It is a score. Under the Nationwide House Energy Rating Scheme, a Whole of Home rating of 100 represents a net zero energy home, and ratings above 100 are possible where a house produces more across the year than it uses. The National Construction Code minimum for a new house is 60. Everything between 60 and 100 is a design decision rather than a regulatory one.
That gap is where the self powering house actually sits. The labels move around, from self powering to net zero to energy positive. The number does not.
What a self powering home actually means
Two ratings sit on a NatHERS certificate and they measure different things. Conflating them is where most of the confusion starts.
The thermal star rating runs from 0 to 10 and covers the building shell only. It answers one question. How much heating and cooling energy does this house need to stay comfortable. It says nothing about what is plugged into it.
The Whole of Home rating runs from 0 to 100. It takes that thermal result and adds the energy used by fixed appliances, heating and cooling, hot water, lighting, cooking and pool or spa equipment, then subtracts energy generated on site by solar and stored in a battery.
Under NCC 2022, a new house has to reach seven stars and a Whole of Home rating of 60. New apartments have to average seven stars, with no apartment below six, and reach a Whole of Home rating of 50.
Which means seven stars and self powering are not the same claim. A seven star house sitting on a Whole of Home score of 60 is fully compliant and will still draw meaningfully from the grid across a year. The homes being described as self powering are the ones scoring at or above 100.
The two numbers on a NatHERS certificate
Thermal star rating. 0 to 10. The shell only. Heating and cooling energy.
Whole of Home rating. 0 to 100. Fixed appliances, hot water, lighting and cooking, offset by solar generation and battery storage. A score of 100 is a net zero energy home. Above 100 means the home produces more than it uses.
NCC 2022 minimum for a new house. Seven stars, and Whole of Home 60.
Why the shell comes before the solar
Jeremy Spencer is a registered builder, energy assessor and director at Melbourne design and build firm Positive Footprints, and a founding director of the Sustainable Builders Alliance. He speaks in the residential stream at the Master Builders Victoria Future Builders Conference in Docklands on 31 August, on the net zero all electric home as a product for the market.
His argument starts with demand rather than generation.
“Unlike traditional homes, these homes have fundamentally low energy needs, which, when coupled with solar production, produce more power each month than they use.”
Jeremy Spencer, Positive Footprints
The sequencing matters commercially, not just technically. Because the Whole of Home rating is a net calculation, every kilowatt hour designed out of a house is a kilowatt hour you never have to generate, store, invert or warrant. Insulation, orientation, glazing and airtightness have no moving parts and no replacement cycle. Panels, batteries and inverters have all three.
Spencer is also the lead writer on the Sustainable Builders Alliance Roadmap to Net Zero Homes, a free industry resource setting out how to design and build for net zero outcomes. For a builder who wants to understand the sequencing without engaging a consultant first, it is a reasonable starting point.
The battery maths changed on 1 May 2026
This is the part most likely to catch a builder quoting work right now.
The federal Cheaper Home Batteries Program has been the single biggest driver of household storage since it opened on 1 July 2025. More than 500,000 batteries had been installed under it by mid August 2026, and the funding was expanded in December 2025 from an original 2.3 billion dollars to an estimated 7.2 billion, with a stated target of more than two million installations by 2030.
The discount structure, however, changed on 1 May 2026, and it changed in a way that directly affects how a system gets sized.
The program still covers battery systems from 5 kWh to 100 kWh nominal capacity, and certificates are only created on the first 50 kWh of usable capacity. Within that, the certificate factor now tapers by tier. The first 14 kWh of usable capacity attracts the full factor. Capacity above 14 kWh and up to 28 kWh attracts 60 per cent. Capacity above 28 kWh and up to 50 kWh attracts 15 per cent.
The tapering is progressive, so a larger battery still draws full support on its lower tiers. The practical effect is that the subsidy no longer scales with size. Under the original settings, going bigger was often close to proportionally cheaper, which is exactly why average system sizes doubled. That is no longer the case. A battery specified for a self powering outcome now needs to be sized against actual household load and inverter output, because the rebate will not carry the difference.
There is a Victorian layer on top of that. The Solar Homes Program still offers eligible households a solar panel rebate of up to 1,400 dollars with an optional interest free loan of the same amount, and it is available to the owner of a home under construction. The combined household income cap dropped from 210,000 dollars to 150,000 dollars on 1 July 2026, and the property has to be valued under 3 million dollars. The state battery loan is closed to new applications, so storage now runs entirely through the federal program.
All of which is worth confirming before a client signs, rather than after.
Blackout backup is a specification, not a feature
The resilience claim is the one most likely to come apart at handover.
A grid connected solar system shuts down when the grid goes down. That is anti islanding, and it is a safety requirement protecting the people working on the network. Panels on the roof and sun in the sky will not keep the lights on by themselves.
Adding a battery does not automatically change that either. A battery installed purely for self consumption, charging by day and discharging at night to cut a bill, will drop out with the grid unless the system has been designed to run islanded.
Three things have to be specified for that to work. A backup capable or hybrid inverter, or a separate backup gateway, that can disconnect the house from the network and form its own supply. A changeover arrangement that does it automatically rather than by hand. And a dedicated backup sub board carrying the circuits that stay live.
The third is where expectations usually break. A battery has a continuous output limit, commonly in the low single digit kilowatts, so whole of house backup is a deliberate design ambition rather than a default setting. Running ducted air conditioning, an electric oven and instantaneous hot water at the same time off a backup circuit is not a given. Which circuits go on the backup board is a conversation that belongs at selection stage, in writing.
Phil Alviano, senior future built environment advisor at Master Builders Victoria, makes a related point. He argues that energy independence is no longer confined to premium homes as solar and battery costs fall, while urging homeowners to press their builders on the quality of the installers, panels and batteries used.
For a builder, that is not a consumer tip. It is a warranty question. The client will not call the installer in three years. They will call whoever signed the contract.
Why this is a product decision, not a compliance one
In Victoria the direction is already legislated. From 1 January 2027 a building surveyor cannot issue a building permit for a new home connected to mains gas, and the trigger is the permit issue date rather than the contract date, so from that point every new Victorian home has to be designed as all electric.
Nationally, the picture is quieter. Building ministers agreed to pause further residential energy changes in the National Construction Code until around 2029. Nobody is being pushed toward 100 on Whole of Home by regulation.
That is precisely what makes it a commercial question rather than a compliance one. Builders have a stable residential ruleset to price against for several years, and a rating tool that already quantifies running cost at design stage. A Whole of Home score is a number a builder can put in front of a client, in writing, before a slab is poured. Very little else in a quote can do that.
Australia now has more than four million rooftop solar systems, roughly one in three homes, and half a million household batteries added in a little over a year. The components are mainstream. What is not yet mainstream is builders knowing, and quoting, where their own standard designs land on the scale.
Five things to check before you quote one
1. Ask your assessor for the Whole of Home score, not just the star rating. Most builders can tell you a design passed. Fewer can tell you the number it passed with.
2. Size the battery against household load and inverter output, not against the rebate tiers. Since 1 May 2026, bigger is no longer proportionally cheaper.
3. Specify backup explicitly. Which inverter, which changeover arrangement, and which circuits sit on the backup board.
4. Confirm rebate eligibility in writing before contract, particularly the Victorian income and property value caps, which tightened on 1 July 2026.
5. Define what self powering means in the contract. Net zero across a year is a very different promise from never drawing from the grid.
The point
The self powering house is not a new idea. What has changed is that the components are affordable, the rating tool measures the outcome, and the number is available to anyone who asks their assessor for it.
The builders who get in front of this will not be the ones with the biggest battery on the roof rack. They will be the ones who can tell a client exactly what a house will cost to run, and then hand over a house that does it.
Spencer presents on the net zero all electric home in the residential stream at the Master Builders Victoria Future Builders Conference, held at the Crowne Plaza in Docklands on 31 August, alongside sessions on renovating for improved performance and on circular design in practice. The full agenda and registration sit on the Master Builders Victoria event page.
Frequently asked questions
A home that generates at least as much energy as it uses across a year. In Australian terms that means a NatHERS Whole of Home rating of 100 or above, where 100 represents a net zero energy home and anything higher means the house produces more than it consumes.
Not on its own. The seven star rating measures the building shell and its heating and cooling demand. Bills also depend on appliances, hot water, and whether solar and storage are installed. That combined picture is the Whole of Home rating, and the code minimum for a new house is 60 out of 100.
Only if the system was designed for it. Grid connected solar shuts down in an outage for safety, and a battery installed for self consumption alone will drop out with it. Backup requires a backup capable or hybrid inverter or gateway, an automatic changeover arrangement, and a dedicated backup sub board. Whole of house backup is also limited by the continuous output of the system.
The program still targets a discount of around 30 per cent, but the certificate factor now tapers by tier. The first 14 kWh of usable capacity attracts the full factor, capacity from 14 to 28 kWh attracts 60 per cent, and capacity from 28 to 50 kWh attracts 15 per cent. Eligible systems run from 5 kWh to 100 kWh nominal, with certificates created on the first 50 kWh of usable capacity only.
No. The current minimum for a new house is seven stars plus a Whole of Home rating of 60, and building ministers have paused further residential energy changes until around 2029. Anything beyond that is a voluntary design and product decision.
The Good Builder Take
There is no regulation forcing anyone to build a self powering home, and there will not be one before the end of the decade. That is the opportunity, not the excuse.
The rating already exists. The number is on the certificate. Most builders have simply never asked for it.
Pull the Whole of Home score on your three best selling designs. If they sit at 60, you now know exactly what you are competing against, and exactly how far you would have to travel to say something a competitor cannot.
Related reading
• NCC 2025 state by state: where the new building code applies now
• New Zealand’s Super Home Movement is proving that building beyond code is practical
• Australian Construction Industry Trends Guide
Sources: NatHERS thermal and Whole of Home rating scales and NCC 2022 minimums, nathers.gov.au. Cheaper Home Batteries Program eligibility, funding and the 1 May 2026 certificate factor tiers, dcceew.gov.au and cer.gov.au. Solar Homes Program rebate values and eligibility caps, solar.vic.gov.au. Victorian building electrification requirements, energy.vic.gov.au. Conference detail and speaker biographies, mbav.com.au. Figures current as at 18 August 2026.
General information only. This article does not constitute legal, financial or professional advice. Builders and homeowners should confirm current rebate eligibility, product specifications and regulatory requirements with the relevant authorities, their building surveyor and an accredited installer before making decisions.
Author: TGB Editorial
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