NatHERS Whole of Home Ratings Explained
Your thermal star rating tells you how comfortable your home is. Your Whole of Home rating tells you what it costs to run. Scored out of 100, it brings together your heating, cooling, hot water, lighting and solar into a single number for your home's total energy performance. Here is what it means, what counts towards it, and how to lift your score.
What is the Whole of Home rating?
The Whole of Home rating is the part of a NatHERS assessment that looks at the energy your home uses to run, not just how well its shell holds temperature. It is scored from 0 to 100 and sits alongside the thermal star rating on your NatHERS certificate.
Where the star rating measures the building envelope, the design, insulation and glazing that keep a home comfortable, the Whole of Home rating adds the major fixed appliances that use energy day to day, then subtracts the energy your rooftop solar generates. The result is a single figure that reflects how energy efficient, and how cheap to run, your home is overall.
It applies right across the scheme: new homes and major renovations, where it forms part of meeting the National Construction Code, and existing homes, where it shows owners how their home performs today and where to improve. The rating grew out of Australia's national plan for low energy buildings, part of the path to net zero by 2050.
Star rating vs Whole of Home rating
Every NatHERS assessment produces two numbers that do two different jobs.
- The star rating measures the shell
Out of 10, it captures how much heating and cooling your home needs to stay comfortable, based on orientation, insulation, glazing and materials. It is a measure of comfort and thermal efficiency, and it does not change with the appliances you install.
- The Whole of Home rating measures the running
Out of 100, it adds the energy used by your fixed appliances and the energy made by your solar. It is a measure of running cost and emissions. This is why two homes with an identical star rating can have very different Whole of Home scores: the one with efficient electric appliances and rooftop solar will rate well ahead of the one running old, inefficient systems.
Put simply, the star rating is about how the home is built, and the Whole of Home rating is about how it is run. You want both working in your favour.
What the Whole of Home rating covers
The rating brings together the energy used by your home's major fixed appliances, offset by what you generate on site. It takes in:
- Heating and cooling. Usually the largest single share of household energy, and the area your thermal star rating influences most.
- Hot water. A major energy user, and one where the choice of system makes a big difference to your score.
- Lighting. The home's fixed lighting and how efficient it is.
- Pool and spa pumps. Where present, these are counted as significant fixed loads.
- Solar and battery. Rooftop solar generation, and any battery storage, are subtracted from the energy your home draws.
Your NatHERS certificate may also show other household energy, such as cooking and plug-in appliances, for information. The regulated Whole of Home score itself focuses on the major fixed appliances above, balanced against your on-site generation.
What the score out of 100 means
The Whole of Home scale runs from 0 to 100, and a higher score means a more efficient, cheaper-to-run home:
- Below 40. A poor performer, typically an older home with inefficient appliances and no solar.
- 60. The minimum a new house must reach to comply with the National Construction Code. New apartments must reach at least 50.
- 100. A net zero energy home, one that generates as much energy as it uses across the year, meaning low or no energy bills.
Above 100. Possible where a home generates more than it uses and exports the surplus.
The score is a strong indicator of running costs and emissions, which is what makes it so useful when comparing homes, planning upgrades, or weighing up solar and electrification.
How to improve your Whole of Home score
Because the Whole of Home score is driven by appliances and generation, it is often the rating you can move fastest, without touching the building shell. The biggest levers are:
- Efficient electric heating and cooling. A modern reverse-cycle system uses far less energy than older electric or gas heating for the same comfort.
- Heat pump hot water. Switching from gas or electric resistive hot water to a heat pump is one of the highest-impact changes for most homes.
- Rooftop solar. On-site generation is subtracted from your energy use, so solar lifts the score directly.
- Battery storage. Storing solar for use after dark increases how much of your own energy you use, supporting a higher score.
- Efficient lighting. Replacing old lighting with LED reduces a small but steady load.
- Going all-electric. Combining efficient electric appliances with solar is the clearest path to a high score and the lowest running costs.
Because we are independent and don't sell any of these products, a NatHERS assessment shows you which upgrades matter most for your home, so you invest in the right order rather than guessing.
When you need a Whole of Home rating
- New homes and major renovations. The Whole of Home rating is part of National Construction Code compliance, with new houses needing at least 60 and new apartments at least 50.
- Existing homes. The rating is included in an existing-home assessment, giving owners a clear picture of running costs and a plan to improve.
- Anyone planning solar or electrification. A rating shows the payoff of going electric and adding solar before you commit, so you can size and stage the work sensibly.
Whichever applies to you, the Whole of Home rating comes as part of a full NatHERS assessment rather than on its own.
Why choose Australian Energy Assessments
We assess Whole of Home performance for new builds, renovations and existing homes, so we understand how the score behaves in each and how to lift it.
We are independent. We don't sell heat pumps, solar or batteries, so when we tell you which upgrade will move your score most, it is because the modelling says so, not because we have stock to shift.
And we translate the numbers into a plan. You get clear, plain-language advice on what to do first and what it is likely to save, so your Whole of Home rating becomes lower bills rather than just a figure on a certificate. Based in Melbourne, working with households across Australia.
Frequently asked questions
What is the NatHERS Whole of Home rating?
It is the part of a NatHERS assessment that scores your home's total energy use out of 100. It combines the energy used by your major fixed appliances with the energy generated by any solar, giving a single measure of how efficient and how cheap to run your home is.
What is the difference between the star rating and the Whole of Home rating?
The star rating out of 10 measures the building shell, how much heating and cooling the home needs. The Whole of Home rating out of 100 adds appliances and subtracts solar, reflecting running costs and emissions. The star rating is about how the home is built, the Whole of Home rating is about how it is run.
What does the Whole of Home rating include?
Heating and cooling, hot water, lighting, and pool or spa pumps, offset by any rooftop solar generation and battery storage. Cooking and plug-in appliances may be shown on the certificate for information, while the regulated score focuses on the major fixed appliances.
What is a good Whole of Home score?
Higher is better. Below 40 is a poor performer, 60 is the compliance minimum for a new house, and 100 represents a net zero energy home with low or no energy bills. Scores above 100 are possible when a home exports more than it uses.
What Whole of Home score does a new home need?
Under the National Construction Code, a new house must reach at least 60 out of 100. New apartments must reach at least 50. These sit alongside the minimum 7 star thermal requirement.
Can a home score over 100?
Yes. A score above 100 means the home generates more energy than it uses across the year, typically through a well-sized solar system, and exports the surplus. These homes usually have very low or no net energy bills.
Does the Whole of Home rating apply to existing homes?
Yes. It is included in a NatHERS assessment for an existing home, giving owners a clear view of running costs and the upgrades that would improve them. For existing homes it is voluntary rather than a compliance requirement.
How is the Whole of Home rating calculated?
An assessor models your home in NatHERS-accredited software, combining its thermal performance with the energy use of its fixed appliances and any solar generation, using local climate data, to produce the score out of 100.
Does solar improve my Whole of Home score?
Yes, directly. Rooftop solar generation is subtracted from the energy your home draws, so adding solar is one of the most effective ways to raise the score.
Does a home battery help the score?
It can. A battery stores solar energy for use after dark, increasing how much of your own generation you use rather than drawing from the grid, which supports a higher Whole of Home score.
Why does going all-electric improve the score?
Efficient electric appliances like reverse-cycle air conditioning and heat pump hot water use less energy than older gas or electric resistive systems, and they pair well with solar. Combining them is the clearest route to a high score.
Does the rating include my fridge, TV and cooking?
Plug-in appliances and cooking may appear on the certificate for information, but the regulated Whole of Home score centres on the major fixed appliances, heating, cooling, hot water, lighting and pool or spa pumps, offset by solar.
Can two homes with the same star rating have different Whole of Home scores?
Yes, and often they do. Two homes with identical shells will score differently if one runs efficient electric appliances and solar while the other runs old, inefficient systems. Appliances and generation are what separate them.
How do I improve my Whole of Home rating?
The highest-impact changes are usually heat pump hot water, efficient reverse-cycle heating and cooling, rooftop solar, and battery storage, supported by efficient lighting. An assessment shows which of these matters most for your home.
Is the Whole of Home rating mandatory?
For new homes and major renovations it is part of National Construction Code compliance. For existing homes it is voluntary, though increasingly valued for planning upgrades, selling or leasing, and green finance.
Does a higher Whole of Home score mean lower bills?
Generally yes. The score reflects how much energy your home draws after solar, so a higher score usually means lower running costs and emissions. A home at or above 100 will have very low or no net energy bills.
What software calculates the Whole of Home rating?
NatHERS-accredited tools such as AccuRate, FirstRate5 and BERSPro for new homes, and AccuRate Enterprise for existing homes. All are built on CSIRO modelling and produce nationally consistent results.
How do I get a Whole of Home rating?
It comes as part of a full NatHERS assessment rather than on its own. Book an assessment with us and you will receive your star rating, your Whole of Home score, and a clear plan for improving both.
Want to know your home's Whole of Home score?
Book a NatHERS assessment and we'll model your home's total energy performance, then show you the upgrades that lift your score and lower your bills the most. Independent advice, no products to sell.