NatHERS Existing Homes
A new pathway to improving home energy performance.
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A Transformative Step for Australian Homes
As part of a new initiative, Australians will have a clear path to improving the comfort and energy efficiency of their homes with the upcoming extension of the Nationwide House Energy Rating Scheme (NatHERS) to existing homes, set to launch mid-2025.
NatHERS, established in 1993, has long provided ratings for new homes, measuring their energy performance based on design, materials, and construction; however, until now, no comprehensive framework has existed for assessing the energy efficiency of existing homes.
The expansion aims to address the energy performance of older homes, which often lack the modern standards for insulation, heating, and cooling efficiency, contributing to higher energy costs and greater environmental impact.
This move aligns with Australia’s broader climate goals, particularly the ambition for net zero emissions by 2050.
Existing homes represent a significant opportunity for improvement, as most were built before current energy efficiency standards were enforced. The Australian government estimates that of the 11 million homes in the country, approximately 70% have an energy rating of 3 stars or less. Improving a home’s rating from 3 stars to 5 stars, for example, could reduce energy usage by around 40% [source].
By enhancing the energy performance of these homes, Australians can not only save on energy bills but also reduce their carbon footprint.
The changes will have the most impact on homeowners in older properties, particularly those built before the introduction of mandatory energy standards.
With this new initiative, the government hopes to boost national efforts toward a more energy-efficient future while supporting individual households through cost-saving upgrades.
Learn more about the Existing Homes expansion here.
What is NatHERS for Existing Homes?
A NatHERS Existing Homes assessment will be conducted by trained and accredited assessors, who will inspect key features of a home and input data into an accredited energy rating tool.
Assessors will evaluate:
- Thermal Performance – This assesses how well a home retains heat in winter and remains cool in summer. Factors examined include insulation levels in walls, ceilings, and floors, the thermal efficiency of glazing, and air leakage through gaps, vents, and poorly sealed areas.
- Whole of Home Energy Performance – This evaluates how efficiently a home uses energy for essential functions. It includes an assessment of heating and cooling systems, hot water systems, lighting, and major appliances such as refrigerators and washing machines. Additionally, on-site energy generation and storage systems, such as solar panels and battery storage, are considered to determine overall energy efficiency.
Key Elements Assessed:
- Climate Zone, Exposure, and Orientation – Assessing the home’s location, sun exposure, and surrounding reflectance.
- Zoning – Evaluating how different areas of the home are used and conditioned.
- Floors – Inspecting insulation levels, materials, and underfloor ventilation.
- Walls – Identifying construction materials, insulation, and exterior colour.
- Windows and Doors – Assessing glazing, framing, and shading properties.
- Ceilings and Roofs – Measuring insulation levels and roof colour.
- Shading – Evaluating eaves, verandahs, and other shading elements.
- Air Leakage and Penetrations – Checking for draughts, vents, and chimney seals.
- Heating and Cooling Systems – Examining installed HVAC systems and efficiency.
- Lighting Systems – Identifying lighting types and energy efficiency.
- Hot Water Systems – Evaluating efficiency and energy sources.
- Pools and Spas – Assessing heating and energy usage.
- On-Site Energy Production and Storage – Factoring in solar panels, batteries, and grid interaction.
The NatHERS Home Energy Rating Certificate
Once an assessment is completed, homeowners will receive a NatHERS Home Energy Rating Certificate.
This document provides a star rating and key insights into the home’s energy performance and potential improvement areas, offering a clear guideline on how to improve energy efficiency.
The certificate serves as a touchpoint with households, helping them understand their home’s energy performance and identify opportunities for improvement.
It includes detailed recommendations on upgrades, such as:
- Insulation improvements
- Appliance efficiency upgrades
- Renewable energy integration
The certificate also aligns with Australia’s Residential Energy Efficiency Disclosure Framework, ensuring consistency in energy performance reporting.
This framework supports mandatory and voluntary disclosure initiatives, allowing homeowners to use their rating in property transactions or to access green loans, rebates, and financial incentives for energy-efficient home upgrades.
Lenders, real estate agents, and policymakers can also leverage this information to encourage investment in sustainable housing solutions.
Upgrade Advice
Homeowners receiving a NatHERS Home Energy Rating Certificate will also gain practical, cost-effective upgrade advice tailored to their home.
The goal is to help reduce energy consumption, lower bills, enhance comfort, and increase the home’s resilience to extreme weather conditions.
The upgrade advice aims to be realistic, and impactful, covering various aspects of home energy efficiency, including:
- General Information and Guidance – Homeowners will receive recommendations on accessing government rebates, financial incentives, and key energy efficiency resources.
- Energy-Saving Tips – Practical strategies such as using curtains to regulate indoor temperatures, optimising air conditioning settings, and zoning to manage heating and cooling more effectively.
- Thermal and Appliance Upgrades – Advice on quick wins like adding ceiling insulation, installing energy-efficient lighting, and switching to heat pump hot water systems.
- Renewable Energy Options – Recommendations on solar PV systems and battery storage to reduce dependence on the grid and take advantage of renewable energy.
- Structural and Ventilation Improvements – Guidance on improving home ventilation to enhance indoor air quality and reduce energy consumption through passive cooling techniques.
- Smart Home Technology – Advice on incorporating smart thermostats and energy monitoring systems to enhance efficiency and convenience.
Why is NatHERS for Existing Homes Being Introduced?
Upgrading Australia’s Housing Stock – Most Australian homes were built before strict energy efficiency standards, with an average thermal performance rating below 3 stars. Many of these homes lack modern insulation, have inefficient appliances, and experience significant energy loss, making upgrades a crucial priority.
Helping Households Save – A home upgraded from 3 to 5 stars could reduce heating and cooling energy use by 40%, significantly lowering bills and improving living conditions, particularly in extreme climates.
Net Zero by 2050 – Residential buildings contribute over 10% of Australia’s emissions; improving energy efficiency will play a key role in emissions reduction. Enhancing home energy performance aligns with Australia’s commitment to international climate targets.
Financial Incentives – Energy ratings will enable access to green loans, government grants, and other financial incentives for home upgrades. These programs encourage property owners to invest in energy-efficient upgrades with potential long-term financial benefits, including increased property value and reduced energy costs.
How Does NatHERS Compare to the Residential Efficiency Scorecard?
The Residential Efficiency Scorecard (Scorecard) was developed by the Victorian Government to assess a home’s energy performance without requiring architectural plans.
This tool enables homeowners to evaluate how efficiently their home uses energy for heating, cooling, and appliances.
The Scorecard uses a star rating system similar to NatHERS but is primarily intended for immediate, practical assessment rather than long-term compliance or regulatory use.
While the Scorecard focuses on operational energy use and household energy consumption patterns, NatHERS for Existing Homes provides a nationally standardised rating framework that aligns with disclosure requirements and financial incentives.
NatHERS integrates software tools that model a home’s thermal performance and its potential energy efficiency improvements.
The key difference is that NatHERS is designed for national implementation and aligns with government initiatives for energy efficiency in real estate transactions, rental properties, and home upgrades.
NatHERS for Existing Homes will incorporate certain methodologies from the Scorecard to enhance its assessment approach, ensuring that Australian homeowners receive comprehensive and actionable energy efficiency ratings.
By combining elements of both programs, NatHERS will offer a robust and transparent system that benefits both individual homeowners and the broader property market.
Developing the Framework
A structured and well-regulated framework is being developed to ensure that NatHERS for Existing Homes operates effectively across different housing types and climate zones. This framework includes:
New Benchmark Tool (CSIRO’s AccuRate Enterprise)
The Existing Homes Benchmark Tool, developed by CSIRO, is a core component of NatHERS for Existing Homes.
This software enables assessors to accurately evaluate a home’s thermal performance and Whole of Home energy efficiency.
The tool provides a comprehensive rating by accounting for factors such as:
- Insulation
- Window glazing
- Shading
- The efficiency of fixed appliances
Assessor Accreditation and Training
Ensuring the quality and consistency of NatHERS assessments requires a rigorous assessor training and accreditation process.
Accredited assessors will undergo formal training to use NatHERS-approved software and apply consistent methodologies for evaluating homes.
The program will establish national standards, ensuring that assessments are uniform, reliable, and transparent.
Legal and Compliance Frameworks
To align with Australia’s broader energy efficiency regulations, NatHERS for Existing Homes will integrate mandatory disclosure requirements where applicable.
This ensures that homeowners, buyers, and renters receive accurate and reliable information about a property’s energy efficiency before making financial commitments.
The compliance framework will also outline penalties for non-compliance and the responsibilities of accredited assessors.
Technical Guidelines and Protocols
A comprehensive set of technical guidelines and protocols will define how assessors evaluate existing homes.
This will include standardised data collection methods, assessment procedures, and software integration requirements.
The guidelines will ensure that ratings are consistent and comparable across different housing types and climate zones.
Energy Rating Tools
The success of NatHERS for Existing Homes relies on advanced energy rating tools that can accurately assess a home’s energy performance.
The Existing Homes Benchmark Tool, developed by CSIRO, will serve as the foundation for this program. The tool will integrate with AccuRate Enterprise software, providing assessors with a scientific and data-driven approach to evaluating homes.
In addition to CSIRO’s tool, third-party user interfaces will be developed to provide homeowners with user-friendly, customised reporting.
These interfaces will make it easier for consumers to understand their home’s energy performance and take actionable steps toward improvement.
National Rollout of NatHERS for Existing Homes
The national rollout of NatHERS for Existing Homes will be coordinated across multiple government levels and involve key stakeholders, including homeowners, real estate agents, banks, and policymakers.
The rollout process will include:
State-Specific Implementation
Each state and territory may adopt NatHERS for Existing Homes at different rates, depending on local regulatory requirements and energy efficiency initiatives.
Some states may implement mandatory disclosure requirements for property sales and rentals, while others may introduce voluntary programs.
Collaboration with Financial Institutions
NatHERS ratings will play a key role in unlocking green loans, home upgrade grants, and financial incentives.
Banks and lenders will use these ratings to assess eligibility for financing programs that support home energy improvements.
Stakeholder Engagement
A major focus of the rollout will be engagement with real estate agencies, valuers, and financing bodies.
These stakeholders will help integrate NatHERS energy ratings into property transactions, making energy efficiency a more significant factor in home-buying decisions.
The Pilot Program: Testing, Refinement & Trials
Before full implementation, a comprehensive pilot program is underway. The primary objectives of this program are to:
- Test the effectiveness of the assessment tools and processes
- Gather feedback from assessors, property owners, and other stakeholders
- Ensure that the program is user-friendly, accurate, and impactful
The insights gained from the pilot will help refine the framework to ensure its applicability across Australia.
In February 2025, NatHERS launched a trial program designed to evaluate how energy efficiency ratings can be applied to existing homes. The trial is an essential step in preparing for the official rollout of the NatHERS Existing Homes rating later in 2025.
Conducted in collaboration with CSIRO, banks, and property professionals, the initiative aims to test the rating process and refine the assessment methodology before making it widely available to homeowners.
The trial consists of two key streams. The Scale Stream, which began in February 2025, involves financial institutions. In this phase, home valuation inspections are used to collect property data, which is then assessed by NatHERS-accredited professionals to generate trial ratings.
The Core Stream, commencing in March, takes a more direct approach, with trained assessors visiting homes to conduct detailed energy assessments. Over 1,000 homeowners have registered interest, and more than 40 assessors are being trained to implement this new rating system.
To ensure consistency in data collection, NatHERS has provided technical guidance documents, equipping assessors with standardised procedures for evaluating homes.
Below we discuss both streams in greater detail.
Core Stream
The Core Stream is designed to establish and validate foundational elements of the NatHERS Existing Homes Scheme.
A primary focus is on the development and testing of tools, ensuring that the Existing Homes Benchmark Tool and AccuRate Enterprise integration are reliable and easy to use.
Tools will be refined to account for varied home types, climate conditions, and available data levels, ensuring their accuracy in calculating both thermal performance and Whole of Home energy ratings.
Another critical aspect of the Core Stream is data collection and analysis. This includes conducting detailed studies on the energy performance of different home types by gathering data on thermal insulation, appliance efficiency, and air leakage.
The collected data will be used to ensure that the assessment tools generate consistent and precise ratings across various property types and climatic conditions.
Training for assessors is also a fundamental component of the Core Stream. The pilot will test the effectiveness of the assessor training program, identifying any gaps in knowledge or resources.
Clear technical guidelines and protocols will be developed to ensure assessors conduct home assessments uniformly and accurately.
To ensure effective adoption of the scheme, household engagement will be a priority. The pilot will test communication strategies aimed at educating property owners about the benefits of participating in the scheme.
Additionally, it will assess the effectiveness of energy-saving advice provided to households during assessments, ensuring it is practical and actionable.
Scale Stream
The Scale Stream expands on the Core Stream by testing the scheme’s ability to operate on a larger scale across diverse Australian housing markets.
The primary goal is to ensure that NatHERS for Existing Homes is scalable and effective in different settings.
A key aspect of this stream is a wider rollout across diverse locations, involving homes in multiple states, regions, and climate zones. This will ensure that the program is adaptable to the varying needs of Australian homeowners and property managers.
The pilot will also include stakeholder collaboration with real estate agencies, banks, and government bodies. This collaboration will test how well the scheme integrates into existing property markets and financial frameworks.
Additionally, the pilot will explore financial incentives such as grants, green loans, or rebates, evaluating their effectiveness in encouraging homeowners to participate.
To refine the implementation strategy, consumer feedback and participation will be actively gathered.
Homeowners who take part in assessments will receive energy performance certificates and tailored upgrade advice. Their feedback will be crucial in shaping the final rollout of the program.
The assessment of program scalability is also a major focus. The pilot will test the scheme’s capacity to handle a high volume of assessments while maintaining quality and accuracy. Identifying potential bottlenecks will help streamline processes before national implementation.
What This Means for Property Owners and Managers
The introduction of NatHERS for Existing Homes will impact homeowners, landlords, and property managers in several key ways:
Mandatory Disclosure
Depending on state regulations, energy ratings may become mandatory when selling or leasing properties. This will increase transparency in the property market, allowing buyers and renters to make more informed decisions.
Financial Incentives for Upgrades
Property owners who invest in energy-efficient upgrades may become eligible for government grants, rebates, and green financing options. These incentives will help homeowners reduce energy costs and increase property value.
Future-Proofing Properties
Energy-efficient homes will become more attractive to buyers and tenants, making them a smarter long-term investment. Upgrading homes to meet higher energy standards can lead to higher resale values and reduced operational costs.
The Role of Accredited Assessors
To ensure accurate and standardised assessments, NatHERS-certified assessors will be responsible for:
- Conducting on-site home energy assessments
- Providing detailed recommendations for energy improvements
- Issuing official NatHERS Energy Rating Certificates to property owners
To maintain the quality and consistency of assessments, assessors will undergo rigorous training and accreditation.
This will include new modules focused on the unique requirements of existing homes. The expanded assessment will also introduce more detailed evaluations, ensuring homes receive a thorough, tailored energy performance rating.
Expert Guidance In Your Home's Energy Performance
By implementing NatHERS for Existing Homes, Australia is taking a significant step toward a more sustainable, energy-efficient future.
Whether you’re a homeowner, buyer, or renter, this initiative provides the tools and insights needed to make smarter energy choices and enhance the value of your home.
As a NatHERS-accredited consultancy, Green Choice Consulting can provide expert guidance in relation to home energy efficiency reports. Contact our assessors today to discuss your options.
