What is NatHERS? Australia's complete guide to home energy ratings.
Every section of the Nationwide House Energy Rating Scheme — star ratings, climate zones, certificates, the Whole of Home pathway — written, charted and explained by Torple Enviro’s accredited assessors.
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Table of Contents
What is NatHERS?
Australia’s homes account for around 10% of the country’s total greenhouse gas emissions — and a large share of that comes from heating and cooling poorly designed buildings. NatHERS was created to change that.
Nationwide House Energy Rating Scheme (NatHERS)
Why NatHERS Matters in Australia
Australia’s diverse climate — from tropical Darwin to cold Hobart winters — means a one-size-fits-all building approach simply doesn’t work. NatHERS accounts for this by mapping the country into distinct climate zones and calibrating assessments accordingly.
Beyond climate, NatHERS is directly tied to legal compliance. Under the National Construction Code (NCC) 2022, new homes must achieve a minimum 7-star NatHERS rating (or equivalent). Without a valid NatHERS certificate, a building permit may not be issued, construction may be delayed, and future sale or rental of the property may be complicated.
Key Reasons NatHERS is Important
- NCC 2022 lifted the minimum star rating from 6 to 7 stars
- Growing consumer demand for energy-efficient, lower-cost-to-run homes
- Mandatory for most new home building approvals across Australian states
- Increasing lender and insurer interest in energy performance data
- Critical for achieving BASIX compliance in NSW and equivalent tools elsewhere
How NatHERS Assessment Works
Software Modelling & Thermal Performance
Accredited NatHERS software tools — including FirstRate5, BERS Pro, and others approved by the government — calculate the estimated annual energy load (measured in MJ/m²) required to maintain a comfortable indoor temperature between 18°C and 26°C. The lower the energy load, the higher the star rating.
What Does the Software Actually Model?
The software simulates your home’s response to every hour of a typical meteorological year — 8,760 hours of sun, wind, rain, and temperature changes — for your specific climate zone. It calculates heat gained and lost through every surface, window, gap, and structural element of the building envelope.
| Building Element | What's Assessed | Why It Matters |
|---|---|---|
| Orientation | Which direction the home faces | Affects solar gain in winter and summer |
| Roof & Ceiling | Material, insulation R-value, colour | Major source of heat gain in summer |
| Walls | Construction type, insulation, mass | Drives heating load in cooler climates |
| Windows & Glazing | Size, type (double/single), shading | Up to 40% of heat loss/gain |
| Floor | Type (slab, suspended), insulation | Affects heating load significantly |
| Air Leakage | Sealing quality and openings | Uncontrolled infiltration wastes energy |
| Shading | Eaves, pergolas, trees, neighbouring buildings | Passive cooling strategy |
| Climate Zone | Bureau of Meteorology zone data | Sets the baseline weather conditions |
Key inputs assessed by NatHERS-accredited software.
Who Conducts a NatHERS Assessment?
Only accredited NatHERS assessors are authorised to produce a legally valid NatHERS certificate. At Torple, our assessors are fully accredited, experienced across all Australian climate zones, and equipped to handle both straightforward residential projects and complex multi-dwelling developments..
NatHERS Star Rating Explained
The NatHERS star rating is the most visible output of an energy assessment — and arguably the most important number on your building compliance documents. Here’s what each band actually means.
0–2★
Very Poor
3–4★
Below Average
5–6★
Old Standard
7★
Current Legal Minimum
8–9★
High Performance
10★
Passive House Level
The NatHERS 0–10 star scale. Each band reflects increasing thermal performance and dramatically lower running costs.
| Stars | Performance Level | What It Means |
|---|---|---|
| 0–2 ★ | Very Poor | Extremely uncomfortable year-round. High energy costs. Unlikely to pass compliance. |
| 3–4 ★ | Below Average | Requires significant heating/cooling. Common in older, uninsulated homes. |
| 5–6 ★ | Adequate (Old Standard) | Met the former NCC minimum (6 stars). Now the baseline — not the goal. |
| 7 ★ | Current Legal Minimum | Required by NCC 2022 for all new homes. Comfortable with moderate energy use. |
| 8–9 ★ | High Performance | Well-designed, energy-efficient home. Significant savings on bills year-round |
| 10 ★ | Passive House Level | Near-zero heating/cooling load. The pinnacle of thermal design in Australia. |
The 7-Star Requirement: What Changed in 2022
Key Reasons NatHERS is Important
If your DA or building permit was submitted before your state adopted NCC 2022, you may be assessed under the older 6-star standard. Torple’s expert assessors will advise which version applies to your specific project.
Unsure if your project meets the 7-star minimum?
Get a clear, no-obligation read on your design. Torple’s accredited assessors will model your home and flag any compliance risks before you lodge.
Heating & Cooling Load Limits
Since NCC 2022, achieving a 7-star rating is only part of the compliance equation. Homes must also meet maximum annual heating and cooling load limits — an important addition that addresses a loophole in the old system.
Why Load Limits Were Introduced
Under the previous NCC framework, a clever design trick was possible: a home could achieve a 6-star (and even a 7-star) rating through a combination of insulation and passive design features, but still have extreme heating or cooling requirements on peak summer or winter days. This meant residents could face enormous energy bills during heatwaves or cold snaps — even in a technically ‘compliant’ home.
To close this loophole, NCC 2022 introduced absolute annual caps on heating and cooling load (measured in MJ/m² per year). These caps apply on top of the star rating — meaning a home must achieve both.
Heating & Cooling Load Caps
Practical Impact
- Early engagement with a NatHERS assessor is now more critical than ever
- Window specifications, glazing ratios, and shading become load-sensitive decisions
- Some designs that ‘look good on paper’ for star ratings may still fail load limits
- Torple can model both criteria simultaneously and flag issues before documentation is finalised
Climate Zones & Their Impact
Australia spans one of the broadest climate ranges of any single country on Earth — from the tropical monsoons of the far north to the alpine winters of the Snowy Mountains. NatHERS is calibrated to account for this diversity through a system of defined climate zones.
| Zone | Climate Type | Key Cities |
|---|---|---|
| 1 | Hot Humid Summer | Darwin, Townsville, Cairns |
| 2 | Warm Humid Summer | Brisbane, Gold Coast, Rockhampton |
| 3 | Hot Dry Summer, Warm Winter | Alice Springs, Longreach |
| 4 | Hot Dry Summer, Cool Winter | Perth, Broken Hill |
| 5 | Warm Temperate | Sydney, Adelaide, Wollongong |
| 6 | Mild Temperate | Melbourne, Canberra |
| 7 | Cool Temperate | Hobart, Ballarat |
| 8 | Alpine | Thredbo, Mount Hotham |
The eight NatHERS climate zones used across Australia.
Design Implications by Climate Zone
Climate zone profoundly shapes design decisions. A wall construction strategy that delivers 8 stars in Brisbane may achieve only 5.5 stars for the identical build in Hobart. This is not a flaw — it’s the system working correctly, ensuring local climate realities are built in from day one.
Zone 1 & 2 (tropical/subtropical): Cross-ventilation, ceiling fans, high thermal mass, shading are king
Zone 5 (Sydney): Balanced approach — must manage both summer cooling and winter heating loads
Zone 6 (Melbourne): Insulation, double glazing, and air sealing become high-priority investments
Zone 7 & 8 (cool/alpine): Passive solar orientation, heavy insulation, and draught-proofing are non-negotiable
NatHERS Certificate (New Homes)
A NatHERS certificate is a formal document issued by an accredited assessor upon completion of a full energy rating assessment. For new homes across most of Australia, this certificate is a mandatory compliance document — not an optional extra.
What’s Included in a NatHERS Certificate
- The property address and full site description
- Climate zone used for the assessment
- The overall star rating achieved (e.g., 7.2 stars)
- Annual heating and cooling load in MJ/m²
- Breakdown of heat flows through each building element
- Software used and assessor accreditation details
- Date of assessment and certificate expiry information
When is a NatHERS Certificate Required?
A NatHERS certificate is required at the building approval (DA/BA) stage for:
- All new Class 1a residential buildings (detached homes, townhouses, duplexes)
- New Class 2 buildings (apartments) in states that apply NatHERS to multi-residential
- Significant extensions or alterations that trigger compliance under the NCC
- Any project using NatHERS as the Deemed-to-Satisfy compliance pathway
Don’t leave it to the last minute
A NatHERS assessment can identify compliance issues before your builder breaks ground — avoiding costly design changes mid-construction.
NatHERS for Existing Homes
NatHERS was originally designed for new construction. But as Australia’s housing stock ages — and as energy prices climb — there is growing demand for NatHERS assessments on existing homes. This is one of the most rapidly evolving areas of energy compliance in Australia right now.
Why Existing Homes Need Energy Ratings
Millions of Australian homes were built before modern energy standards existed. These homes often have minimal insulation, single-glazed windows, and poor air sealing — making them expensive to run and uncomfortable to live in. A NatHERS assessment for an existing home identifies exactly where the thermal performance gaps are and what can be done about them.
| Scenario | Why a NatHERS Assessment Helps |
|---|---|
| Home sale or purchase | Buyers increasingly want to know the star rating before committing |
| Rental property upgrade | Minimum energy standards for rentals are being introduced in multiple states |
| Renovation planning | Identify which upgrades deliver the highest return on energy performance |
| Green finance applications | Some lenders offer better rates for higher-rated homes |
| NABERS or Greensmart targets | NatHERS is an input to broader sustainability goals |
| Government rebate eligibility | Some state and federal retrofit programs require a baseline rating |
Common scenarios where existing-home NatHERS assessments deliver value.
How NatHERS for Existing Homes Works
Assessing an existing home follows a similar process to a new build, but with some key differences. The assessor must gather information about the actual construction of the home — including existing insulation levels, window types, and wall/floor systems — through a combination of site inspection, photographs, and documentation review.
Where specifications are unknown or unverifiable, the software applies default ‘worst case’ assumptions — which may result in a lower-than-actual star rating. Providing as much documentation as possible (original plans, previous assessments, product specs) helps achieve the most accurate result.
Status of the Program
A ‘NatHERS for Existing Homes’ assessment is not currently mandatory under the National Construction Code (NCC). The program is still in its trial and early rollout phase. However, assessments are increasingly relevant.
Whole of Home (WoH) Ratings
NatHERS has traditionally focused on the thermal shell of a home — the walls, roof, windows, and floor. The Whole of Home (WoH) rating represents the next evolution of residential energy compliance in Australia, and it’s already embedded in the NCC 2022 framework.
What Whole of Home Covers
While the NatHERS thermal rating measures how much energy is needed to heat and cool a home, the Whole of Home rating goes further by accounting for all energy used in the home, including:
- Space heating and cooling systems (HVAC)
- Hot water systems (gas, electric, heat pump, solar)
- Lighting and plug loads
- On-site energy generation (solar PV)
- Battery storage and feed-in tariffs
The WoH Vision
Under NCC 2022, a home’s energy budget is calculated holistically. A home with excellent thermal performance but an inefficient gas hot water system may still fail the WoH pathway. Conversely, a solar PV system can offset energy use and help borderline designs achieve compliance.
Whole of Home and the Future of Compliance
As more homes go electric and rooftop solar becomes the norm, the Whole of Home pathway is set to become the standard way new homes demonstrate energy compliance. Our assessors are fully trained in Whole of Home modelling and can help you choose the right appliances and systems to get the best possible outcome for your project.
NatHERS for Alterations & Extensions
Not all NatHERS work involves brand-new homes. A significant share of the assessments Torple conducts relate to alterations and extensions — modifications to existing buildings that trigger new compliance requirements.
When Does an Alteration Need a NatHERS Assessment?
Compliance is triggered when the scale or nature of the work crosses specific thresholds defined in the NCC and state planning codes. Common triggers include:
- Adding a new room, storey, or habitable floor area
- Replacing the roof over a large portion of the building
- Installing new windows or glazing systems
- Any work that requires a building permit and changes the thermal envelope
Partial Assessments: How They Work
When only part of a home is being altered, a partial or incremental NatHERS assessment may be appropriate. In this approach, only the altered section is modelled against current NCC standards, while the existing structure is assessed under the standards applicable at the time of original construction.
This can be a more practical and cost-effective approach for homeowners undertaking single-room additions or targeted renovations.
Free Scope Review
Unsure whether your project triggers NatHERS compliance? Torple offers a free initial scope review. Contact us at torple.au before lodging your DA.
One assessment. Every compliance question answered.
Whether it’s a new build, an extension, or an existing-home retrofit, Torple models it all under one roof — accredited, fast, and pragmatic.
NatHERS vs Other Compliance Pathways
NatHERS is one of several energy and sustainability compliance tools used in Australian construction. Understanding how it relates to — and differs from — other schemes is essential for architects, builders, and developers navigating a complex regulatory landscape
NatHERS vs BASIX (NSW Only)
BASIX (Building Sustainability Index) is a NSW Government tool that covers water efficiency and thermal comfort for all new residential development in NSW. NatHERS is used as the thermal modelling engine within BASIX — a home that achieves the required NatHERS star rating satisfies the BASIX thermal commitments.
| Feature | BASIX | NatHERS |
|---|---|---|
| Geography | NSW only | All of Australia |
| Scope | Thermal + Water | Thermal only (+ WoH) |
| Tool | BASIX online tool | Accredited software |
| Output | BASIX Certificate | NatHERS Certificate |
NatHERS vs BESS
BESS (Built Environment Sustainability Scorecard) is a Victorian local government sustainability assessment tool used by many Melbourne councils. BESS uses NatHERS star ratings as an input but adds further sustainability criteria including site stormwater, landscape, daylight, and materials. A high NatHERS star rating helps but does not guarantee a passing BESS score.
NatHERS vs Green Star
Green Star is the Green Building Council of Australia’s voluntary rating system for buildings, fitouts, and communities. It is typically applied to commercial buildings, residential apartment towers, and precinct developments. While NatHERS and Green Star both relate to energy efficiency, they operate at different scales and for different project types. A NatHERS certificate does not contribute to a Green Star rating, though both may apply to large apartment projects.
NatHERS vs VURB
Both are building permit compliance pathways under NCC 2022 for residential thermal performance. NatHERS uses accredited software (e.g. FirstRate5) to achieve a minimum 7-star rating for Class 1 and Class 2 buildings. VURB (Verification Using a Reference Building) is a performance-based alternative under NCC Volume Two Part H6, comparing your proposed design against a code-compliant reference building using ANSI/ASHRAE Standard 140-compliant software — NatHERS tools are not permitted under VURB. VURB suits complex designs where standard star ratings prove costly or unachievable.
Benefits of NatHERS
A NatHERS certificate is legally required — but the benefits of a well-designed, high-rated home extend far beyond compliance.
$
Energy Cost Savings
A 7-star home can use up to 24% less heating/cooling energy than a 5-star equivalent — thousands saved over a decade.
°C
Improved Comfort
Stable indoor temperatures year-round without constant reliance on HVAC. Especially impactful for young or elderly residents.
Resale Value
Australian real estate increasingly correlates star ratings with property value. A high rating is a marketable asset.
Co₂
Environmental Impact
Every home built to 7+ stars rather than the old 6-star baseline contributes meaningfully to Australia’s net-zero goals.
Common Mistakes to Avoid
After hundreds of assessments across Australia, Torple’s assessors have identified the same mistakes appearing on project after project. Most of them are entirely avoidable with early engagement.
01 Engaging an assessor too late — after plans are finalised and building is about to commence. At this stage, design changes to improve ratings are costly or impossible.
02 Ignoring climate zone implications during the design phase. A window placement that works in Queensland can cause compliance failure in Victoria.
03 Underspecifying insulation. Minimum-spec insulation often produces ratings at or below 7 stars, leaving no buffer if construction variances arise.
04 Window-to-wall ratios exceeding the thermal budget. Large glass areas are popular aesthetically but often the single biggest compliance risk.
05 Not documenting as-built changes. If the builder substitutes a specified product during construction, the certificate may be invalidated.
06 Assuming a previous version of the NCC applies. With states adopting NCC 2022 at different times, always verify which code version applies to your project.
07 Overlooking the heating/cooling load caps in favour of focusing only on the star rating.
Most expensive mistake
Unsure whether your project triggers NatHERS compliance? Torple offers a free initial scope review. Contact us at enquiry@torple.au before lodging your DA.
Step-by-Step Process
Here is how a typical NatHERS assessment journey works with Torple, from initial enquiry to final certificate.
01 Initial Enquiry
Contact Torple via torple.au. We review your project type, location, and timeline.
02 Documentation Review
Submit plans, specifications, and any existing energy documents. We identify gaps or clarification needs.
03 Climate Zone Check
We confirm which NatHERS climate zone applies to your site and which NCC version governs your project.
04 Preliminary Modelling
We run an initial assessment to identify any compliance risks while there is still time to address them.
05 Design Feedback
If upgrades are needed, we provide specific, cost-effective recommendations to reach the target rating.
06 Final Assessment
We run the final model against agreed specifications and confirm compliance.
07 Certificate Issued
Your accredited NatHERS certificate is issued and ready for submission with your DA or building permit.
08 As-Built Review (Optional)
If specifications change during construction, we update the model and reissue the certificate as required..
Frequently Asked Questions
What is a NatHERS rating?
A NatHERS rating is a star rating from 0 to 10 that measures the thermal efficiency of a home. It is calculated using accredited energy modelling software based on the home’s design, materials, orientation, and climate zone. A higher rating means less energy is needed for heating and cooling.
What star rating is required for new homes in Australia?
Under the National Construction Code (NCC) 2022, all new homes must achieve a minimum 7-star NatHERS rating. States and territories are adopting NCC 2022 progressively from May 2023.
How much does a NatHERS assessment cost?
The cost of a NatHERS assessment in Australia typically ranges from $300 to $800 for a standard residential dwelling, depending on complexity, location, and whether alterations are involved. Contact Torple at torple.au for a tailored quote.
How long does a NatHERS assessment take?
For a standard new home, a NatHERS assessment typically takes 2–5 business days once all documentation has been received. Complex projects or those requiring design feedback iterations may take longer.
Can an existing home get a NatHERS rating?
Yes. NatHERS assessments can be conducted on existing homes. These assessments are used for retrofit planning, property transactions, rental compliance, and eligibility for government rebate programs. Torple offers a dedicated NatHERS for Existing Homes service.
What is the difference between NatHERS and BASIX?
NatHERS is the national energy efficiency scheme for all of Australia, measuring thermal performance. BASIX is a NSW Government tool that uses NatHERS modelling as one component, alongside water efficiency measures. BASIX applies only in NSW; NatHERS applies nationally.
What is a NatHERS certificate?
A NatHERS certificate is a formal document issued by an accredited NatHERS assessor confirming a home’s star rating and compliance with energy efficiency requirements. It is required as part of the development approval or building permit process for new homes in most Australian states.
Does NatHERS cover solar panels?
Traditional NatHERS thermal assessments do not include solar panels. However, the Whole of Home (WoH) pathway — introduced in NCC 2022 — does include on-site energy generation (including solar PV), battery storage, and hot water systems in the compliance calculation.