NatHERS for existing homes trial

To ensure energy ratings for existing homes under NatHERS are effective, the new systems, tools and processes will be trialled ahead of its launch.

NatHERS is running a trial in partnership with the CSIRO, on behalf of all states and territories, from late 2024 into 2025.

The trial will test the tools and processes used to rate the energy performance of existing homes across Australia. It will provide households with insights to plan energy upgrades and help shape a national energy rating system.

There are two trial streams:

Core stream – where a trial assessor completes all elements of the assessment, including undertaking the NatHERS for existing homes training, collecting data on-site, and using the trial assessment tool to produce a home energy rating.
Scale stream – where property valuers collect data on-site and work with NatHERS assessors to complete the assessment off-site and produce a rating.

Both streams support innovation in data collection and assessment by using mobile devices for collecting data in homes and the cloud-based energy rating tool developed by CSIRO called ‘AccuRate Enterprise’.

The core stream will test energy rating tools, assessor training, assessment processes and assurance elements required to launch NatHERS for existing homes.

The scale stream will see banks partner with property valuer data collectors and current NatHERS assessors for new homes to test delivering existing home energy assessments at scale.

The benefits of taking part in this trial

Households participating in this trial will receive a free home energy rating assessment and trial certificate. The trial provides:

Insights into your home's energy performance and how it compares to other homes in Australia.
Guidance for planning energy-efficient upgrades.

By participating, you will play a role in shaping the future of home energy ratings and will contribute to policies that promote sustainable energy use and lower greenhouse gas emissions.

Getting ready for a home assessment

Preparing for the assessment is simple and straightforward.

For homes participating in the core stream of the trials, an assessor will contact you to schedule a time to inspect your property. For scale stream participants appointments will be organised through participating valuation companies.

During the visit, the assessor will evaluate all areas of your home, including attached garages and shading structures.

To ensure the process runs smoothly, you can take the following steps:

Make sure all rooms and areas are easily accessible and free of clutter.
Secure any pets and open window coverings to allow clear visibility.
If applicable, provide information about recent upgrades, such as insulation improvements or receipts for renovations.

These small preparations will help the assessment proceed efficiently.

About your trial certificate

All participating households will receive a Home Energy Rating trial certificate from their trial assessor. While the official Home Energy Rating certificate is under development for the launch of NatHERS for existing homes in 2025, the trial certificate contains most features planned for the official version. These include:

a NatHERS Star Rating (out of 10)
a Home Energy Rating (out of 100)
a breakdown of the energy used by your appliances
estimates of your home’s annual energy use and greenhouse gas emissions
the renewable energy profile for your home (if relevant).

You can use the trial certificate to:

Identify areas where energy efficiency can be improved.
Discuss potential upgrades with energy professionals or assessors.
Inform future home improvement plans, potentially increasing energy savings and comfort.

Your trial certificate cannot be used for regulatory compliance for new homes or major renovations.

About your ratings

NatHERS home energy ratings are a reliable guide to predicting and comparing the energy performance of homes. Information collected about your home and appliances is entered into a computer model which uses local climate data and standardised assumptions for occupant behaviour to predict the energy required to heat and cool your home and its overall energy performance.

Your certificate contains two ratings:

Star Rating

Homes are given a star rating between 0 and 10. This is based on the home’s heating and cooling needs, taking into account its local climate, design, materials and construction. This includes the:

layout of the home and its orientation
- roof, walls, windows and floor, construction methods and materials
- shading from the sun's path and how well it takes advantage of local breezes.

Energy assessors use NatHERS computer modelling tools to predict the amount of heating and cooling your home will need to stay comfortable year-round. This is called thermal performance.

Below is a general guide to ratings:

A 0-star rated home is quite uncomfortable – too hot in summer and too cold in winter. It will require a lot of energy to heat and cool.
A home reaching a 7-star rating will need a small amount of mechanical heating and cooling to keep it comfortable to live in. This is the minimum standard for new houses under the National Construction Code 2022.
A 10-star home is very energy efficient. It will remain comfortable year-round, with little to no mechanical cooling or heating.

Home Energy Rating

Homes are given a home energy rating on a scale of 0 to 100.

The home energy rating builds on the thermal performance star rating by providing information about the energy use of your whole home.

The rating considers the home’s thermal performance, energy used for heating and cooling, and major appliances, minus energy generated from solar panels, building a useful energy snapshot of energy costs as well as greenhouse gas emissions.

Appliances assessed as part of your home energy rating include:

Heating and cooling
Hot water system
Lighting
Pool/spa pump
On-site energy generation and storage.

Homes with higher energy ratings cost less to run. They have better designs, efficient appliances and may also generate their own electricity.

While the Whole of Home rating scale ranges from 0 to 100 (where 100 is a net zero energy value home), ratings above 100 are possible. One way that a home may rate over 100 is where a home generates more energy than it uses.

How does your home compare?

Most Australian homes were built before the introduction of minimum energy performance requirements. They were also designed with little consideration of the local climate which can significantly impact the energy efficiency of your home. The average home in Australia has an estimated star rating of less than 3 out of 10 stars.

Currently, the minimum star rating for a new home under the updated National Construction Code 2022 is 7 stars and the minimum Whole of Home rating is 60 out of 100 for houses and 50 out of 100 for apartments, although this varies across the different states and territories.

Home energy upgrades

Quick wins such as draught proofing, better insulation, installing quality window coverings and external shading can improve comfort and reduce energy bills. More extensive upgrades, such as full electrification of appliances and installing rooftop solar, can also save energy and money in the long term, but have higher upfront costs.

The costs, benefits and feasibility of these options will vary for each home, depending on its construction and local climate.

You will receive upgrade advice with information on options to improve your home’s energy performance following your home’s assessment, alongside your trial certificate.

Additional resources are available at:

Contact us

For queries or support regarding NatHERS trials of existing home ratings, email trials@nathers.gov.au.

Core stream trial EOI - closed

NatHERS received more than 150 applications from individuals wanting to take part in the core stream existing homes trial.

Applicants will undertake training before conducting up to 20 trial home energy assessments across Australia, including in regional areas. Feedback will help improve how NatHERS for existing homes is designed and delivered.  

A diverse range of applications were received from:

individuals new to the field 
professionals with broader property or construction experience 
accredited NatHERS, Residential Efficiency Scorecard and Energy Efficiency Rating assessors.

Trial participants will help shape the future of a significant national energy efficiency initiative and benefit from:   

fully subsidised training 
funded real-world experience conducting existing home energy assessments 
a streamlined pathway to becoming an accredited NatHERS existing homes assessor.

The Expression of Interest for this trial closed on Wednesday 27 November 2024.

Scale stream trial EOI – closed

The scale stream trial Expression of Interest closed on Monday 11:59 PM (AEDT) 2 December 2024.