Green Star Homes vs NatHERS

Green Star Homes and NatHERS both relate to better home performance, but they are not the same system. NatHERS is an Australian home energy rating scheme that assesses the thermal performance of a home. Green Star Homes is a broader residential sustainability rating tool that considers healthy, efficient, resilient and future ready housing outcomes.

The simplest way to understand the difference is this: NatHERS helps show how much heating and cooling a home is likely to need to stay comfortable. Green Star Homes looks at the home more broadly, including comfort, health, electrification, renewable energy, water, resilience and positive environmental outcomes. NatHERS Green Building Council of Australia

What NatHERS is designed to do

NatHERS stands for the Nationwide House Energy Rating Scheme. It provides a star rating out of 10 for the thermal performance of a home. NatHERS explains that the rating considers factors such as the home’s design, orientation, construction materials and local climate. The higher the star rating, the less energy the home is expected to need for heating and cooling to stay comfortable. NatHERS

This makes NatHERS especially important for understanding the building fabric. Orientation, window size, glazing type, shading, insulation, wall construction, roof construction, floors, ceiling heights and climate zone can all affect the result.

In practical terms, NatHERS helps project teams understand how well the home moderates heat and cold before mechanical systems are considered. A strong NatHERS outcome usually reflects a home that has been designed with climate, comfort and building fabric in mind.

What Green Star Homes is designed to do

Green Star Homes is broader than a thermal performance rating. The Green Building Council of Australia describes Green Star Homes as having three categories focused on the core outcomes that define a healthy, resilient and positive home. Green Building Council of Australia

This means Green Star Homes looks beyond how much heating and cooling a home may need. It considers the wider sustainability quality of the home, including energy, health, indoor environment quality, resilience, water, materials, electrification and renewable energy readiness.

For a residential project, NatHERS can be one important part of the performance story. Green Star Homes is closer to the whole story of the home as a sustainable place to live.

The main difference between Green Star Homes and NatHERS

The main difference is scope. NatHERS is focused on thermal performance. Green Star Homes is focused on broader residential sustainability.

In practical terms, the difference can be understood like this:

• NatHERS rates the thermal performance of a home out of 10 stars.
• Green Star Homes rates broader residential sustainability outcomes.
• NatHERS focuses mainly on heating and cooling energy needs.
• Green Star Homes includes health, resilience, electrification, renewables, water and broader environmental outcomes.
• NatHERS is commonly used for compliance and residential energy performance documentation.
• Green Star Homes is generally a voluntary higher level sustainability rating for new homes.
• NatHERS is one important input into understanding comfort and building fabric.
• Green Star Homes uses a broader lens to consider the whole home as a healthy and resilient place to live.

Does Green Star Homes replace NatHERS?

No. Green Star Homes does not replace NatHERS where NatHERS is required or used as part of a residential assessment pathway.

A project may still need NatHERS modelling to support BASIX, NCC energy efficiency requirements or broader residential energy performance documentation. Green Star Homes may sit above this work by setting a wider sustainability ambition, but it does not remove the need to understand the home’s thermal performance.

This is why NatHERS and Green Star Homes should usually be seen as complementary. NatHERS helps measure a key part of home performance. Green Star Homes helps frame a broader sustainability outcome.

Where Green Star Homes and NatHERS overlap

The strongest overlap between Green Star Homes and NatHERS is thermal comfort. A home that performs well thermally is usually more comfortable, easier to heat and cool and more stable across seasonal changes.

The main areas of overlap include:

• Orientation and solar access.
• Window size, placement and glazing performance.
• Summer shading and winter solar gain.
• Wall, roof, floor and ceiling insulation.
• Thermal mass and lightweight construction choices.
• Climate responsive design.
• Heating and cooling demand.
• Occupant comfort and lower running costs.

These are not only technical modelling issues. They shape the lived experience of the home. A poorly orientated home with large unshaded glazing may struggle with overheating. A well insulated home with carefully shaded windows may feel calmer, more stable and less dependent on mechanical cooling.

Where Green Star Homes goes beyond NatHERS

NatHERS is a powerful thermal performance tool, but it is not designed to assess every sustainability outcome. It does not, by itself, provide a complete picture of whether a home is fossil fuel free, renewable powered, water efficient, low impact, healthy or climate resilient.

Green Star Homes can extend the conversation into:

• All electric home design.
• Renewable energy readiness and solar integration.
• Indoor air quality and healthy materials.
• Water efficiency and drought resilience.
• Operational emissions.
• Climate adaptation and resilience.
• Material impacts and waste reduction.
• Broader wellbeing and liveability outcomes.

This is one of the reasons Green Star Homes may be attractive to developers, builders and housing providers who want to demonstrate a stronger sustainability position than a thermal rating alone can communicate.

How Whole of Home fits into the picture

NatHERS is no longer only about the thermal shell in every context. For new homes, residential energy performance is increasingly connected to Whole of Home considerations, including major appliances and systems such as heating, cooling, hot water, lighting, pool pumps, solar PV and batteries where relevant.

This matters for Green Star Homes because services and operational energy are central to the future of sustainable housing. A home with good thermal performance can still perform poorly if its services are inefficient, fossil fuel dependent or poorly coordinated. A home with efficient all electric services and solar may align more strongly with lower operational energy and future ready housing outcomes.

For many projects, the most useful approach is to consider NatHERS, Whole of Home and Green Star Homes together. NatHERS helps explain the thermal fabric. Whole of Home helps explain major household systems. Green Star Homes helps frame the wider sustainability ambition.

Practical considerations for project teams

For architects, builders and developers, the most important practical point is that thermal performance should not be left until the end of design. NatHERS outcomes are strongly affected by early design decisions, especially orientation, glazing, shading and building fabric.

Review glazing early

Glazing can strongly influence NatHERS performance and Green Star Homes outcomes. Window size, orientation, frame type, glass performance and shading should be reviewed before elevations and window schedules are fixed.

Coordinate shading with climate

Shading needs to respond to orientation and climate. Good shading can reduce summer overheating while still allowing useful winter sun where appropriate. Poor shading can increase cooling loads and reduce comfort.

Treat insulation as part of the whole fabric

Insulation needs to work with the roof, walls, floors, glazing, ventilation and construction method. Simply increasing insulation without understanding the whole building fabric may not solve the key performance issue.

Think about comfort, not only compliance

A compliant NatHERS result is important, but the design team should also think about how the home will feel in real use. Stable indoor temperatures, good daylight, controlled heat gain, natural ventilation and appropriate services all contribute to a more liveable home.

Keep sustainability claims aligned with evidence

If a project is described as sustainable, high performance or Green Star Homes aligned, the supporting documentation should be consistent. NatHERS, Whole of Home, specifications, product selections and design commitments should all support the same performance story.

How Certified Energy can help

Certified Energy prepares NatHERS assessments and supports residential project teams with building performance, BASIX, Whole of Home and broader sustainability advice.

For projects exploring Green Star Homes principles, our team can help review how the home’s thermal performance supports the wider sustainability goal. This may include reviewing glazing, shading, insulation, construction assumptions, climate zone, services and the relationship between the building fabric and operational energy.

The aim is not simply to produce a rating. It is to help the design team understand how the home performs as a system, so compliance documentation and sustainability intent are moving in the same direction.

Related resources

• Green Star Homes Knowledge Hub
• NatHERS Knowledge Hub
• BASIX Knowledge Hub
• Whole of Home Knowledge Hub
• Home Energy Rating Knowledge Hub
• Passive House Knowledge Hub
• ESD Consultancy

Frequently asked questions

Is Green Star Homes the same as NatHERS?

No. NatHERS rates the thermal performance of a home, usually out of 10 stars. Green Star Homes is a broader residential sustainability rating tool that considers health, resilience, energy, water, electrification, renewables and wider environmental outcomes.

Does Green Star Homes replace NatHERS?

No. Green Star Homes does not replace NatHERS where NatHERS is required or used for residential energy performance documentation. NatHERS can support Green Star Homes outcomes, but it remains a separate assessment pathway.

What does NatHERS measure?

NatHERS measures the thermal performance of a home. It considers factors such as climate, orientation, glazing, shading, construction materials, insulation and design to estimate heating and cooling needs.

Can a high NatHERS rating support Green Star Homes?

Yes. A strong NatHERS result can support Green Star Homes thinking because it helps demonstrate good thermal performance, comfort and reduced heating and cooling demand. However, Green Star Homes considers broader outcomes beyond thermal performance alone.

Is NatHERS only for new homes?

NatHERS has historically been used for new homes and major renovations, and it is also being expanded for existing homes through the Home Energy Rating framework. The relevant assessment pathway depends on whether the project is a new build, renovation or existing home rating.

Should project teams think about NatHERS early?

Yes. NatHERS outcomes are strongly affected by early design decisions such as orientation, glazing, shading, insulation and construction type. Early review can help avoid late design changes and support better sustainability outcomes.