NatHERS Existing Homes Assessment: Complete Guide (2026)
Australia is rolling out energy ratings for existing homes under NatHERS. In March 2026, all governments agreed to a new data collector pathway that will scale assessments nationwide. Here's everything you need to know.
Taylor M
NatHERS & Home Energy Specialist
March 2026 Update: New Data Collector Pathway Agreed
In March 2026, all Australian governments agreed to expand the NatHERS existing homes delivery model to include an additional data collector training and accreditation pathway. This means trained data collectors — not just fully accredited assessors — will be able to gather on-site information, helping to scale the program faster. The pathway is expected to open from late 2026.
Quick Answer
A NatHERS existing homes assessment rates your home's energy performance on a 0–10 star scale plus a Whole-of-Home score out of 100. A certified assessor visits your property, measures construction details, and models the results in accredited software. Costs range from $300–$800 and the program is scaling rapidly toward broad availability from mid-2026.
What Is a NatHERS Existing Homes Assessment?
A NatHERS existing homes assessment measures the energy performance of a home that has already been built. Previously, the Nationwide House Energy Rating Scheme (NatHERS) only applied to new builds and major renovations. The expansion now brings the same trusted framework to Australia's 11 million+ existing homes.
The assessment produces two key outputs:
Star Rating (0–10)
Measures thermal performance — how much heating and cooling your home needs to stay comfortable. A 10-star home needs almost no artificial climate control.
Whole-of-Home Score (0–100)
Includes thermal performance plus the energy used by fixed appliances (hot water, heating, cooling, lighting) and any on-site solar generation and storage.
Unlike new build assessments that work from architectural plans, existing home assessments require a physical on-site inspection. The assessor measures and records real-world construction details, making the rating a true reflection of the home's current condition.
Want a quick estimate? Try our free energy rating calculator — it takes under 2 minutes.
Get Your EstimateThe New Data Collector Pathway (March 2026)
In a significant development, all Australian governments agreed in March 2026 to expand the NatHERS existing homes delivery model to include an additional data collector training and accreditation pathway.
This decision followed a public consultation undertaken in late 2025 and is designed to rapidly scale the workforce needed to meet growing demand for existing home assessments.
What the Data Collector Pathway Means
- Two-tier workforce: Trained data collectors can gather on-site information (measurements, photos, construction details), while accredited assessors complete the modelling and issue the certificate
- Faster scaling: Data collector training is shorter and more accessible, allowing the workforce to grow faster than if every participant needed full assessor accreditation
- Lower costs: By separating data collection from modelling, the overall cost of assessments may decrease as efficiency improves
- Available from late 2026: Training will open to interested individuals, creating new career opportunities in the energy efficiency sector
This is a game-changer for the industry. The biggest bottleneck in the existing homes program has been the limited number of accredited assessors. With data collectors handling the on-site work, a single assessor can process significantly more ratings — bringing assessments to more Australians, faster.
How the Assessment Works
Step 1: On-Site Inspection (1–2 Hours)
A certified assessor (or in future, a trained data collector) visits your home to record construction details. They use tools like MagicPlan to create a precise digital floor plan, capturing:
- Floor plan, room dimensions, and orientation
- Wall, floor, and ceiling construction materials
- Insulation type and thickness
- Window glazing, size, frame type, and placement
- Fixed appliances (hot water, HVAC, lighting)
- Solar panels and battery storage
Step 2: Energy Modelling
The collected data is entered into NatHERS-accredited software such as AccuRate Enterprise, developed by CSIRO. The software simulates how much energy the home uses throughout the year based on local climate data, producing the star rating and Whole-of-Home score.
Step 3: Certificate Issued (2–5 Business Days)
You receive a formal NatHERS Certificate with your results and, in Stage 2, personalised upgrade recommendations to improve your rating.
Ready for an official assessment? Find certified NatHERS assessors in your area.
Find Local AssessorsWhat You Receive
Your NatHERS Existing Homes Certificate includes:
- Star rating (0–10): Your home's thermal performance rating
- Whole-of-Home score (0–100): Combined thermal, appliance, and solar performance
- Heating and cooling loads: Measured in MJ/m² per year
- Construction summary: Floor plan and key building details
- Upgrade guidance (Stage 2): Home-specific recommendations to improve your rating
This certificate can be used for property sales, rental listings, green finance applications, or simply understanding your home's energy performance before planning upgrades.
Rollout Timeline
September 2024 — Trials Begin ✅
Field trials of tools and processes commenced in partnership with CSIRO.
March 2025 — Delivery Model Agreed ✅
Energy Ministers agreed the delivery model for NatHERS existing homes ratings.
July 2025 — Stage 1 Release ✅
First assessors accredited, first-generation software released, policies established.
January 2026 — Scale-Up Training ✅
Industry Transition Training opened for 120 targeted assessors. Assessor Accreditation Service Provider and auditors commenced.
March 2026 — Data Collector Pathway Agreed 🆕
All Australian governments agreed to expand the delivery model with an additional data collector training and accreditation pathway.
Mid-2026 — Stage 2 Release 🔜
Updated second-generation software, improved certificates with upgrade guidance, training and accreditation open to all applicants.
Late 2026 — Data Collector Training Opens
The new data collector pathway training opens to interested individuals.
Beyond Stage 2
Further software improvements, third-party user interfaces, and expanded household resources.
How Much Does It Cost?
Current NatHERS existing homes assessments typically cost between $300 and $800, depending on:
- Location: Metropolitan areas generally have more assessors and competitive pricing
- Home size and complexity: Larger homes with multiple storeys or unusual construction take longer
- Assessor availability: Currently limited during the scale-up phase
As the workforce scales with the data collector pathway and Stage 2 opens accreditation to all applicants, costs are expected to become more competitive. For a detailed pricing breakdown, see our Home Energy Rating Cost Guide.
Take the Next Step
Whether you're curious about your home's efficiency or ready to get a professional assessment, we have tools to help.
Estimate Your Rating
Use our free calculator to get an instant estimate of your home's energy star rating.
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Browse certified NatHERS assessors in your area and connect directly.
View DirectoryFind Local Services
Explore energy rating services specific to your city or state across Australia.
Explore LocationsReady to get started? Request free quotes from certified assessors.
Request Free QuotesReady to find out your home's energy rating? Find a certified NatHERS assessor near you
Who Needs an Assessment?
Homeowners
Understand your home's performance, identify the most impactful upgrades, and cut energy bills. A higher rating can also increase your property value.
Sellers & Agents
NSW is trialling mandatory disclosure at point of sale. Other states are expected to follow. Getting rated early gives you a competitive edge.
Banks & Lenders
Ratings can verify green loan applications, helping banks access green capital markets and homeowners secure better financing for upgrades.
Renovators
Get a baseline rating before renovating, then use the upgrade guidance to maximise the energy efficiency gains from your investment.
How to Prepare for Your Assessment
To help your assessor complete the inspection efficiently and accurately:
- Provide access to all rooms, including roof space and under-floor areas where possible
- Gather documentation: building plans, renovation records, or insulation certificates
- Note any upgrades made since original construction (new windows, insulation, solar panels)
- Allow 1–2 hours for the on-site inspection — most assessments are non-disruptive
Victorian Scorecard Closure (June 2026)
The Residential Efficiency Scorecard program, administered by the Victorian Government, will close on 23 June 2026. Scorecard was a successful first step in rating existing homes, and NatHERS for existing homes is the direct successor.
Accredited Scorecard assessors are being supported with a streamlined transition pathway to NatHERS accreditation. For more on this transition, read our detailed guide: Scorecard to NatHERS Transition.
NSW Disclosure Trial
NSW is leading a national trial of mandatory home energy rating disclosure at the point of sale or lease. The trial tests the nationally agreed Home Energy Ratings Disclosure Framework, including training for real estate agents and resources for consumers.
Findings will inform when NSW transitions to mandatory disclosure and help other states considering similar requirements. For NSW-specific guidance, see our NSW energy rating selling guide.
Frequently Asked Questions
What is a NatHERS existing homes assessment?
It's an on-site energy rating of a home that has already been built. A certified assessor inspects the property, measures construction details, and uses accredited software to calculate a star rating (0–10) for thermal performance and a Whole-of-Home score (0–100) covering appliances and solar.
What is the new data collector pathway?
Agreed by all Australian governments in March 2026, it creates a new role where trained data collectors can gather on-site information, which is then used by accredited assessors to complete the rating. This separates the physical inspection from the technical modelling, allowing the workforce to scale faster.
How much does an assessment cost?
Typically $300–$800 depending on location, home size, and complexity. Costs are expected to decrease as the workforce scales with the data collector pathway and Stage 2 rollout.
When will assessments be widely available?
Stage 2, expected from mid-2026, will open training and accreditation to all applicants and release updated software. The data collector pathway training opens from late 2026.
Is an assessment mandatory?
Not yet nationally. NSW is trialling mandatory disclosure at point of sale. The ACT has an existing EER disclosure scheme. Other states are expected to introduce requirements as the program matures.
What's the difference between this and the Victorian Scorecard?
The Scorecard program closes on 23 June 2026. NatHERS for existing homes is its successor — a national program that aligns existing home ratings with the established NatHERS framework used for new builds. Scorecard assessors can transition to NatHERS accreditation via a streamlined pathway.
Can I use my rating for a green loan?
Yes. Banks can use NatHERS existing homes ratings to verify green loan applications. This helps them access green capital markets and offer better financing terms for energy-efficient homes and upgrades.
Official Government Resources
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