NatHERS for Existing Homes: New Requirements & What You Need to Know (2025 Update)
A major change is coming to Australian property: NatHERS energy ratings for existing homes. Here's everything homeowners need to know about the new requirements, timelines, and what it means for property sales.
Taylor M
NatHERS & Home Energy Specialist
Quick Answer
Yes, Australia is introducing NatHERS energy ratings for existing homes from 2025. The program will be rolled out progressively across states and territories. While initially voluntary, many jurisdictions are moving toward mandatory disclosure at point of sale. This means if you're planning to sell your home in the coming years, you'll likely need an energy rating assessment.
What Is NatHERS for Existing Homes?
Until now, NatHERS (Nationwide House Energy Rating Scheme) has only applied to new builds and major renovations. In March 2025, the Australian Government released the official delivery model for extending NatHERS to existing homes.
This is a significant expansion of the scheme that will eventually cover millions of existing residential properties across Australia.
Key Features of the New Program:
- On-site assessments: Unlike new builds (assessed from plans), existing homes require physical inspections
- Dual scoring: Homes receive a star rating (0-10 stars) plus a Whole-of-Home score (0-100)
- Certified assessors: Only trained NatHERS assessors can conduct existing home assessments
- Disclosure ready: Certificates designed for property sales and rental listings
When Will It Be Mandatory?
The rollout is happening in phases, and requirements vary by state and territory:
2025: Pilot Phase
Voluntary assessments available nationwide. Early adopters can get ratings before mandatory requirements begin.
2025-2026: Progressive Rollout
States begin introducing mandatory disclosure requirements, typically at point of sale or for rental properties.
- ACT: Leading with early implementation (expected 2025)
- Victoria: Residential Efficiency Scorecard program expansion
- NSW & QLD: Consultation phases underway for 2026 implementation
2027 Onwards: Nationwide Coverage
All jurisdictions expected to have disclosure requirements in place, with most linked to property transactions.
Important: Timelines and requirements are subject to change. Each state and territory will announce their specific implementation dates and rules. Stay updated through your local government energy efficiency websites.
When Do I Need an Assessment?
While requirements vary by jurisdiction, common triggers for needing an existing home energy rating include:
Property Sales
Most states are implementing mandatory disclosure at point of sale. Sellers will need to provide an accredited NatHERS certificate to potential buyers, similar to building and pest inspections.
Rental Properties
Some jurisdictions are requiring energy ratings for rental properties, helping tenants understand energy costs before leasing.
Voluntary Assessments
Even before mandatory requirements, homeowners can request assessments to understand their home's efficiency, plan upgrades, or gain a competitive advantage in the market.
Want a quick estimate? Try our free energy rating calculator — it takes under 2 minutes.
Get Your EstimateHow Much Does It Cost?
Costs for existing home NatHERS assessments are generally lower than new build assessments:
Factors affecting cost:
- Home size (number of rooms and living areas)
- Location (urban vs regional pricing)
- Complexity (multi-story, unique features, accessibility)
- Assessment urgency (rush fees may apply)
- Additional testing (if blower door test or thermal imaging requested)
💡 Tip: Get quotes from multiple certified assessors through our free service to ensure competitive pricing for your area.
The Assessment Process
Understanding what happens during an existing home energy rating assessment:
Book Your Assessment
Contact a certified NatHERS assessor who is qualified for existing homes. Find assessors in Sydney, Melbourne, Perth, or browse all locations.
On-Site Inspection
The assessor visits your home (typically 1-3 hours) to inspect insulation, windows, heating/cooling systems, ventilation, and building envelope. They may take measurements and photos.
Data Analysis
The assessor inputs data into approved NatHERS software, which calculates your home's thermal performance and energy efficiency rating.
Certificate Issued
You receive an official NatHERS certificate showing your star rating (0-10) and Whole-of-Home score (0-100), plus recommendations for improvements.
What the Assessor Will Evaluate:
- ✓ Ceiling and wall insulation
- ✓ Window types and glazing
- ✓ Building orientation and shading
- ✓ Air leakage and ventilation
- ✓ Heating and cooling systems
- ✓ Hot water system type
- ✓ Floor insulation (if applicable)
- ✓ Building materials and construction
Understanding Your Rating
Existing homes receive two complementary scores:
Star Rating (0-10 stars)
Measures thermal performance - how much heating and cooling your home needs to maintain comfort.
Whole-of-Home Score (0-100)
Comprehensive score including thermal performance, appliances, lighting, solar panels, and other energy-using features.
Higher scores = Lower energy bills and reduced environmental impact
Benefits of Getting Rated Early
Even if not yet mandatory in your area, there are advantages to getting an assessment now:
Selling Advantage
A good energy rating can differentiate your property in the market and appeal to environmentally conscious buyers willing to pay a premium.
Plan Improvements
Understand your home's weaknesses and prioritize cost-effective upgrades that will have the biggest impact on comfort and bills.
Access Rebates
Some government rebate programs require or prioritize homes with energy ratings, helping you access funding for upgrades.
Avoid Rush Fees
Beat the rush before mandatory requirements begin. Demand will surge, potentially causing delays and higher prices.
Ready for an official assessment? Find certified NatHERS assessors in your area.
Find Local AssessorsWhat If My Home Gets a Low Rating?
First, don't panic. The rating is for disclosure, not compliance - you can still sell or rent your home with any rating.
Common Upgrades to Improve Ratings:
- Add ceiling insulation: Often the most cost-effective upgrade (typical ROI: 2-3 years)
- Upgrade windows: Double glazing or secondary glazing in key areas
- Seal air leaks: Draught-proofing doors and windows
- Install efficient heating/cooling: Reverse cycle air conditioners over resistive heaters
- Add window coverings: Curtains, blinds, or external shading
- Install solar panels: Improves Whole-of-Home score significantly
Your assessment report will include specific recommendations tailored to your home's characteristics.
Frequently Asked Questions
Do I need a new rating if I make improvements?
Not immediately. Ratings are typically valid for 10 years unless significant modifications are made. However, getting a new rating after major upgrades can demonstrate improved performance.
Will a low rating stop me from selling?
No. The rating is for disclosure only. However, properties with higher ratings may sell faster and potentially achieve higher prices, while lower-rated homes might need price adjustments or improvement investments.
Can I do the assessment myself?
No. Only accredited NatHERS assessors can issue official certificates. They have specialized training and must use approved software. DIY estimates have no legal validity.
What's the difference from new build ratings?
New builds are assessed from plans and require minimum 7 stars in most areas. Existing homes are assessed as-built with physical inspections, have no minimum requirement (disclosure only), and include the Whole-of-Home score.
How long does an assessment take?
The on-site inspection typically takes 1-3 hours depending on home size and complexity. You'll usually receive your certificate within 5-10 business days after the inspection.
Key Takeaways
- NatHERS for existing homes is rolling out progressively from 2025 across Australia
- Most states will require disclosure at point of sale within the next 2-3 years
- Assessments cost $300-$800 and involve on-site inspections by certified assessors
- Ratings are for disclosure, not compliance - you can sell with any rating
- Getting rated early can provide selling advantages and help plan improvements
Ready to Get Your Home Energy Rating?
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