What 7 Stars Means for Your Home
If you’re planning a new home, renovation or residential development in Australia, you’ve likely come across the term NatHERS star rating. With minimum energy efficiency standards increasing under the National Construction Code (NCC), understanding what a 7-star rating means, and how it affects your project, is now essential.
NatHERS star ratings play a central role in demonstrating thermal performance, securing building approvals and improving the long-term comfort and efficiency of Australian homes.
This guide explains how NatHERS star ratings work, what 7 stars really means, and how they fit into broader energy efficiency requirements.
Table of Contents
What Is a NatHERS Star Rating?
NatHERS, or the Nationwide House Energy Rating Scheme, is Australia’s framework for assessing the thermal performance of residential buildings.
A NatHERS star rating measures how efficiently a home’s design maintains comfortable indoor temperatures throughout the year.
Ratings are issued on a scale from 0 to 10 stars, with higher ratings indicating better thermal performance and lower reliance on artificial heating and cooling. Importantly, a NatHERS star rating focuses on the building fabric – not appliances or occupant behaviour.
A higher star rating generally means:
- Improved year-round thermal comfort
- Lower heating and cooling energy demand
- Reduced running costs over time
How NatHERS Star Ratings Are Calculated
NatHERS star ratings are generated using accredited thermal modelling software, such as FirstRate5 or AccuRate. These tools simulate how a home performs under standard occupancy conditions based on detailed design inputs.
Key factors assessed include:
- Local climate zone
- Orientation and layout
- Construction materials and thermal mass
- Insulation levels
- Window size, type and glazing
- Shading and ventilation
Only NatHERS-accredited assessors are authorised to complete assessments and issue certificates. Their role is to ensure the dwelling is accurately modelled and assessed in accordance with NatHERS protocols and NCC requirements.
Understanding NatHERS Climate Zones
Australia is divided into multiple NatHERS climate zones, each reflecting different temperature patterns and heating and cooling demands. Because climate conditions vary significantly across the country, the same house design can achieve very different star ratings depending on its location.
For example, a design that performs well in a mild coastal climate may struggle to meet requirements in a colder alpine or hotter inland region without adjustment. NatHERS software applies climate-specific heating and cooling targets to ensure homes are designed for their local conditions.
Understanding your climate zone early in the design process helps ensure materials, glazing and layout decisions support energy efficiency and compliance.
What Does a 7-Star NatHERS Rating Mean?
A 7-star NatHERS rating indicates that a home has been designed to require relatively low amounts of energy for heating and cooling. Under the NCC 2022 energy efficiency provisions, 7 stars is now the minimum standard for most new residential buildings in Australia.
Compared to the previous 6-star minimum, a 7-star home typically offers:
- More stable indoor temperatures
- Less reliance on heating and cooling systems
- Improved comfort during extreme weather
- Lower long-term energy costs
Increasing the minimum NatHERS requirement from 6 stars to 7 stars is expected to reduce heating and cooling energy use in new homes by around 25% (source).
A 7-star rating does not mean a home is “zero energy”, but it does represent a well-designed, thermally efficient dwelling suitable for its climate.
Is a 7-Star NatHERS Rating Mandatory?
In most states and territories, a minimum 7-star NatHERS rating is required for new residential buildings under NCC 2022, subject to local adoption timelines and project type.
NatHERS assessments are commonly used to demonstrate compliance for:
- Class 1 buildings (houses and townhouses)
- Class 2 buildings (apartments and multi-unit developments)
- Class 4 dwellings within non-residential buildings
While alternative compliance pathways exist, NatHERS remains the most widely accepted and straightforward method for meeting residential thermal performance requirements across Australia.
How to Achieve a 7-Star NatHERS Rating
Achieving a 7-star NatHERS rating is less about adding expensive technology and more about making informed design decisions early in the process.
The way a home is designed, its layout, orientation and materials, has a greater impact on star ratings than individual fixtures or finishes.
One of the most important factors is orientation. Living areas positioned to capture winter sun, with appropriate shading to limit summer heat gain, can significantly reduce heating and cooling demand.
Poor orientation often requires higher insulation levels or glazing upgrades to compensate, which can increase construction costs.
Insulation and building fabric also play a critical role. This includes wall, roof and floor insulation, as well as how well the building envelope limits unwanted heat transfer. Gaps, thermal bridging and inconsistent insulation can reduce performance even in otherwise well-designed homes.
Windows and glazing are another key consideration. Window size, placement, frame type and glazing performance all affect heat gain and loss.
Strategic window placement, combined with suitable glazing and shading devices, can improve comfort while maintaining natural light and ventilation.
Other factors that influence star ratings include:
- Ceiling heights and room volumes
- External shading such as eaves, screens and landscaping
- Use of thermal mass in appropriate climates
- Natural ventilation pathways and the inclusion of ceiling fans
Engaging a NatHERS assessor during the design phase allows these elements to be modelled and optimised before plans are finalised. This approach often reduces the need for costly changes later and helps ensure compliance is achieved efficiently.
Can Homes Achieve More Than 7 Stars?
Yes – NatHERS ratings extend up to 10 stars, and many homes can achieve higher than the minimum 7-star requirement when passive design principles are incorporated from the early design stages.
Homes rated 8 stars or above are typically designed to work with their local climate rather than against it. Passive design focuses on reducing the need for mechanical heating and cooling by carefully managing heat gain, heat loss and airflow throughout the year.
Key passive design principles that support higher NatHERS star ratings include:
- Orientation that maximises winter solar gain while minimising summer heat exposure
- Effective insulation across walls, roofs and floors to limit unwanted heat transfer
- High-performance glazing combined with appropriate shading to control heat gain and loss
- Thermal mass, such as concrete or masonry, used strategically to store and release heat
A 10-star home represents a theoretical benchmark where the dwelling can maintain comfortable indoor temperatures year-round with little to no artificial heating or cooling under standard conditions. While achieving 10 stars is uncommon, it demonstrates the performance potential of well-executed passive design.
For many projects, exceeding the minimum 7-star requirement can deliver benefits beyond compliance, including:
- improved comfort
- lower ongoing energy costs
- greater resilience to temperature extremes
However, pursuing higher star ratings should be considered alongside site constraints, budget and construction complexity.
A NatHERS assessment allows these passive design elements to be modelled and refined, helping designers and homeowners understand the most effective ways to improve performance without unnecessary cost.
NatHERS Star Rating vs Whole of Home Energy Rating
While often discussed together, the NatHERS star rating and the Whole of Home Energy Rating measure different aspects of a dwelling’s performance.
The NatHERS star rating focuses exclusively on thermal performance: how the building shell responds to its climate and how much energy is required to maintain comfortable indoor temperatures. It does not consider appliances, lighting efficiency or renewable energy systems.
The Whole of Home Energy Rating, introduced under NCC 2022, assesses the efficiency of fixed services and systems, including:
- Heating and cooling equipment
- Hot water systems
- Fixed lighting
- On-site renewable energy, such as solar panels and batteries
This rating is scored out of 100, with higher scores indicating lower overall energy use and greenhouse gas emissions. Unlike the star rating, it reflects how systems perform in combination with the building fabric.
Together, these assessments provide a more complete picture of a home’s energy performance:
- The star rating addresses passive thermal efficiency
- The Whole of Home rating addresses active energy use
Understanding both helps designers, builders and homeowners make informed decisions about comfort, compliance and long-term running costs.
Do Renovations and Existing Homes Need a 7-Star Rating?
NatHERS requirements for renovations, alterations and extensions depend on the scope of work and local approval requirements. In many cases, only the altered portion of the dwelling is assessed.
At the same time, NatHERS is expanding beyond new builds to include existing homes, giving homeowners a clearer understanding of how older properties perform and where improvements can be made.
This is particularly important given that around 70% of Australia’s existing housing stock was built before modern energy efficiency standards were introduced and is estimated to perform at 3 stars or less, according to federal government analysis (source).
By extending NatHERS to existing homes, this framework now provides structured insights into both thermal performance and whole-of-home energy use, supporting better renovation decisions and long-term efficiency upgrades.
More information is available on our NatHERS Existing Homes page.
Why Work With an Accredited NatHERS Assessor?
Only accredited NatHERS assessors can complete compliant assessments and issue certificates accepted by councils and certifiers. Accreditation ensures assessors are trained, audited and up-to-date with NCC requirements.
An experienced assessor can:
- Identify compliance risks early
- Recommend practical design improvements
- Help avoid delays and redesign costs
- Ensure documentation meets approval requirements
At Green Choice Consulting, our accredited assessors provide clear, compliance-focused advice across residential and multi-dwelling projects nationwide.
Frequently Asked Questions About NatHERS Star Ratings
What is a NatHERS certificate?
A NatHERS certificate confirms that a dwelling has been assessed using approved NatHERS software and shows the achieved star rating and heating and cooling loads.
Does a higher star rating increase build costs?
Not always. Many improvements can be achieved through design optimisation rather than expensive materials, particularly when addressed early.
Can I improve my star rating after plans are drawn?
In many cases, yes. Adjustments to glazing, insulation or shading can improve performance without major redesign.
Is NatHERS the same as BASIX or NABERS?
No. NatHERS assesses thermal performance, BASIX applies in NSW and includes water and energy targets, and NABERS measures operational energy use in existing buildings.
Learn more about the difference between NatHERS and BASIX here.
Does a NatHERS star rating affect resale value?
While star ratings are not always listed in property advertising, higher-rated homes are generally more comfortable and cheaper to run, which can improve buyer appeal. As energy efficiency becomes more visible and regulated, star ratings are expected to play a larger role in property value.
How long does a NatHERS assessment take?
The assessment timeframe depends on project complexity and the quality of documentation provided. Most single-dwelling assessments can be completed within a few business days once all required plans are received.
Can a NatHERS rating be updated if plans change?
Yes. If design changes occur after an assessment, the model can be updated to reflect the revised plans. This is common during design development and approval stages.
Does a NatHERS star rating guarantee low energy bills?
A higher star rating reduces heating and cooling demand, but actual energy bills also depend on appliance efficiency, system selection, energy plans and prices, and occupant behaviour.
Do all councils require a NatHERS certificate?
Most councils accept NatHERS certificates as a primary method for demonstrating residential thermal performance compliance, but requirements can vary by jurisdiction and project type.
Is it possible to fail a NatHERS assessment?
Yes. If a design does not meet the required minimum star rating or heating and cooling load targets, it will need to be revised before a compliant certificate can be issued.
Can the same home design achieve different star ratings?
Yes. The same design can achieve different star ratings depending on orientation, site conditions and climate zone. Minor changes to layout or window placement can also influence results.
Designing for Comfort, Compliance and Efficiency
Understanding NatHERS star ratings, particularly the 7-star minimum, helps ensure your project meets compliance requirements while delivering comfortable, energy-efficient living spaces.
Whether you’re designing a new home, planning a renovation or working on a residential development, engaging an accredited NatHERS assessor early can streamline approvals and improve long-term outcomes.
If your project requires a NatHERS assessment or certificate, Green Choice Consulting can help ensure your design meets NCC energy efficiency requirements with confidence.
Contact us today to discuss your project needs.
Albert Burton is the founder of Green Choice Consulting, leading a national team that delivers fast, accurate ESD reports for residential and commercial projects. With expertise in sustainability and business, he leverages advanced technology to streamline compliance and reduce costs for clients.