NatHERS Star Ratings

Can a Home Achieve 10 Stars in NatHERS?

A 10 Star NatHERS rating represents the top of the thermal star rating scale. It is possible in theory, but uncommon in practice and highly dependent on site, climate and design quality.

What a 10 Star NatHERS rating means

NatHERS ratings run from 0 to 10 stars. A higher rating means the home is expected to need less heating and cooling to remain comfortable in its local climate. A 10 Star rating sits at the highest end of that scale.

In practical terms, a 10 Star home is one where the building fabric, orientation, layout, glazing, shading, insulation and construction systems are working together extremely effectively. The design is expected to moderate heat and cold with very little reliance on mechanical heating or cooling.

This does not mean the home uses no energy overall. NatHERS thermal star ratings focus on heating and cooling demand created by the home’s design and fabric. Other household energy use is considered separately through broader energy pathways such as Whole of Home where applicable.

Is 10 Stars realistic for Australian homes?

A 10 Star rating is possible, but it is not realistic for every site or every design brief. Very high NatHERS ratings usually require the architecture, site planning and construction approach to be shaped around thermal performance from the beginning.

Some sites make high ratings easier. Good solar access, favourable orientation, compact form, protected exposure and opportunities for effective shading can all help. Other sites are more difficult because of overshadowing, poor orientation, exposure, planning constraints or a design brief that requires large areas of glazing or complex forms.

For most projects, the more practical question is not whether 10 Stars can be reached, but what level of performance is appropriate, buildable and valuable for the home.

What helps a home reach very high NatHERS ratings?

Very high NatHERS ratings are usually created by the whole design working together. One product upgrade is rarely enough. The home needs to reduce heating and cooling demand through the way it is planned, detailed and constructed.

The strongest outcomes usually come from design coordination, not from chasing a single specification. Glazing, shading, insulation, roof colour, floor construction and climate response need to be resolved as part of one system.

Why 10 Stars is not always the right target

Although 10 Stars sounds ideal, it is not automatically the right target for every project. A very high rating may require design changes, construction upgrades or cost increases that need to be weighed against the project’s goals.

In some projects, moving from a compliant rating to a slightly higher rating may deliver meaningful comfort and performance benefits. In others, the last few increments toward 10 Stars may require changes that are difficult to justify in terms of budget, architecture or buildability.

A balanced approach is to understand the compliance requirement first, then consider whether higher performance targets such as 8 Stars, 9 Stars or 10 Stars make sense for the design.

10 Stars and passive design

Very high NatHERS ratings are closely connected to passive design. Passive design uses the site, orientation, shading, insulation, glazing, thermal mass and ventilation strategy to help the home stay comfortable naturally.

A home aiming for 10 Stars usually needs passive design thinking to be embedded early. This can involve orienting living areas carefully, controlling sun exposure, reducing unwanted heat transfer and choosing construction systems that suit the climate.

This is why high performance homes often feel calm rather than complicated. The building fabric is doing much of the work quietly, before active systems need to respond.

How 10 Stars connects to compliance

A 10 Star rating is well above the usual compliance target for most new homes. Current residential compliance conversations more commonly focus on meeting the applicable thermal performance benchmark, often connected with 7 Star Rating requirements or equivalent pathways.

In NSW, the NatHERS result may also need to align with BASIX. A higher rating does not remove the need for the correct certificates, commitments or project documentation.

For broader energy requirements, Whole of Home may also need to be considered. A strong thermal rating is valuable, but it is still one part of the wider residential energy pathway.

Design considerations for Australian homes

Very high NatHERS ratings require a design response that suits the local climate. In cooler regions, heat retention, insulation and winter solar access may be central. In hot regions, shading, roof colour, glazing control and cooling load reduction may matter more.

Compact building form, orientation, shading, window placement and construction detailing often become more important as rating targets rise. The design needs to reduce avoidable heating and cooling demand before relying on equipment or generation.

Because the pathway can be sensitive, high performance targets should be discussed early. This gives the design team the best chance of integrating performance without compromising the architecture or creating late documentation changes.

Working with Certified Energy

Certified Energy provides NatHERS assessments for new homes, townhouses and multi residential projects across Australia. Our team can model the proposed design and help identify whether a high performance target such as 8, 9 or 10 Stars is realistic for the project.

Where needed, we can help project teams understand which design factors are influencing the rating, including orientation, glazing, insulation, shading, roof colour, thermal mass, floor construction and local climate zone. We can also help connect the assessment with related requirements such as NatHERS, 7 Star Rating, BASIX and Whole of Home.

For a broader explanation of the rating framework, visit our NatHERS Knowledge Hub.

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