NatHERS and Whole of Home
NatHERS vs Whole of Home: What Is the Difference?
NatHERS and Whole of Home are closely connected, but they measure different parts of residential energy performance. NatHERS focuses on the thermal shell of the home. Whole of Home looks at broader energy use and generation.
The difference in brief
NatHERS thermal star ratings assess the heating and cooling needs created by a home’s design, construction, materials and local climate. Whole of Home assesses the broader energy performance of the entire home, including major fixed appliances, heating and cooling equipment, hot water, solar and batteries where applicable. They are related, but they are not the same assessment.
What NatHERS measures
NatHERS is most commonly understood through the thermal star rating. This rating shows how well the home is expected to manage heat and cold in its local climate. It estimates the amount of heating and cooling that may be needed to keep the home comfortable across the year.
The thermal rating focuses on the building fabric. This includes the orientation, layout, walls, roof, floor, windows, insulation, glazing, shading, construction materials, roof colour and local climate zone.
In simple terms, NatHERS asks: how much heating and cooling does this home’s design need in order to stay comfortable?
What Whole of Home measures
Whole of Home looks beyond the building fabric. It considers the broader energy performance of the whole dwelling, including the systems and appliances that use or generate energy.
This can include heating and cooling equipment, hot water systems, lighting, pool and spa pumps where relevant, cooking appliances, plug loads, solar photovoltaic systems and batteries. The exact inputs depend on the project and the applicable assessment requirements.
In simple terms, Whole of Home asks: how much energy is the home expected to use overall, and how do installed systems or generation affect that outcome?
The practical distinction
NatHERS thermal rating: how well the home’s fabric reduces heating and cooling demand.
Whole of Home: how the home’s major energy uses, systems, solar and batteries contribute to the broader energy result.
Why both matter
A home can have a strong thermal shell but still use a lot of energy if the installed systems are inefficient or the energy profile is poorly balanced. Likewise, a home may include efficient appliances or solar but still feel uncomfortable if the building fabric performs poorly.
This is why NatHERS and Whole of Home should be understood as complementary. NatHERS focuses on reducing the need for heating and cooling through better design. Whole of Home looks at how the rest of the home’s energy picture performs once systems and appliances are considered.
Together, they support a more complete view of residential performance: the home’s fabric, the systems inside it and the energy used or generated over time.
How this connects to NCC residential energy requirements
Under updated residential energy efficiency settings, new homes may need to demonstrate both thermal performance and broader whole home energy performance. NatHERS thermal ratings are commonly used to demonstrate the thermal performance side, while Whole of Home addresses the annual energy use budget for the dwelling.
This means project teams should not assume that achieving a strong NatHERS star rating automatically resolves every energy requirement. The thermal star rating and Whole of Home result may both need to be checked as part of the compliance pathway.
Implementation can vary by state, territory, project type and approval timing, so the applicable requirements should be confirmed for the specific project before finalising the pathway.
A useful way to think about it
If the question is about insulation, glazing, shading, orientation and heating or cooling demand, you are usually looking at NatHERS thermal performance.
If the question is about hot water, appliances, equipment efficiency, solar, batteries and total home energy use, you are usually looking at Whole of Home.
If the question is about residential energy compliance, both may need to be considered together.
Common points of confusion
One common misunderstanding is that Whole of Home replaces NatHERS. It does not. Whole of Home adds a broader energy view, while the NatHERS thermal star rating remains focused on the heating and cooling needs created by the home’s design and fabric.
Another misunderstanding is that solar panels can compensate for poor thermal design. Solar can improve the broader energy result, but it does not change the need for a home to have an appropriate thermal shell. A poorly performing home may still be uncomfortable, even if it has energy generation onsite.
A third issue is treating appliances and systems as a late selection. Because Whole of Home can depend on system choices, those decisions may need to be coordinated with the energy assessment rather than left until the end of documentation.
Design considerations for Australian homes
Good residential performance usually starts with the building fabric. Orientation, shading, insulation, glazing and construction choices shape how much heating and cooling the home needs before any appliance or system is considered.
Whole of Home then adds another layer. The selected hot water system, heating and cooling equipment, cooking appliances, solar and battery assumptions can influence the overall result. These decisions should be checked against the project’s compliance requirements and design intent.
The strongest outcomes occur when thermal performance and whole home energy decisions are coordinated early. This helps avoid late changes, inconsistent specifications or a design that performs well in one area but struggles in another.
Working with Certified Energy
Certified Energy prepares NatHERS assessments and supports Whole of Home pathways for Australian residential projects. Our team reviews the design, models the thermal performance and helps project teams understand how building fabric decisions connect with broader energy compliance.
Where relevant, we can help coordinate related requirements including NatHERS, Whole of Home, 7 Star Rating and BASIX for NSW projects.
For a broader explanation of NatHERS and residential thermal performance, visit our NatHERS Knowledge Hub. For the broader energy systems pathway, visit our Whole of Home Knowledge Hub.
FAQ
Are NatHERS and Whole of Home the same thing?
No. NatHERS thermal star ratings focus on the home’s heating and cooling needs. Whole of Home looks more broadly at energy use across the home, including major appliances, systems, solar and batteries where applicable.
Does Whole of Home replace NatHERS?
No. Whole of Home does not replace the NatHERS thermal star rating. They assess different parts of residential energy performance and may both be relevant under current energy efficiency requirements.
What does Whole of Home include?
Whole of Home can include major energy uses and systems such as heating and cooling equipment, hot water, lighting, appliances, solar and batteries where applicable.
Can solar panels improve Whole of Home?
Solar panels may improve the Whole of Home result because they affect the broader energy profile of the dwelling. They do not replace the need for an appropriate NatHERS thermal star rating.
Should NatHERS and Whole of Home be considered together?
Yes. NatHERS and Whole of Home are best considered together because building fabric, systems, appliances and solar assumptions can all affect the final residential energy compliance pathway.
