NatHERS Assessment Process

Who Can Perform a NatHERS Assessment?

A NatHERS assessment should be completed by someone who understands residential thermal performance, accredited software, building fabric and the compliance pathway for the project.

What a NatHERS assessor does

A NatHERS assessor reviews the home design and models its thermal performance using accredited software. The assessment considers the dwelling layout, orientation, local climate, glazing, shading, insulation, roof, walls, floors, ceilings and other construction details.

The assessor’s role is not only to enter data into software. They need to understand how the design and building fabric affect heating and cooling demand, and whether the documentation supports the intended compliance pathway.

When the assessment is complete, the result can be used to support residential energy compliance for the project, depending on the state, territory and approval pathway.

Why accreditation matters

Accreditation matters because NatHERS assessments are used in a compliance context. The model needs to be prepared correctly, the software settings need to be applied appropriately and the final documentation needs to align with the project information.

A small modelling error can affect the rating, especially where the project is close to the required threshold. Glazing values, orientation, shading, insulation placement, roof colour, floor construction and climate zone all need to be entered and interpreted carefully.

A qualified assessor can also help identify whether missing or unclear documentation may affect the assessment, rather than relying on assumptions that may later need to be corrected.

Can an architect perform a NatHERS assessment?

Architects and building designers play an important role in shaping the NatHERS outcome. Orientation, windows, shading, roof form, room layout and construction systems are all design decisions that affect thermal performance.

However, for compliance purposes, the NatHERS assessment should be completed by someone suitably trained or accredited to carry out the assessment using approved software. Some architects may also hold energy assessment accreditation, but the roles should not be assumed to be the same.

The strongest process is usually collaborative: the designer shapes the home, and the assessor models and tests how the design performs thermally.

Can a builder perform a NatHERS assessment?

Builders are essential to the final performance of the home because they deliver the construction details that the assessment relies on. Insulation placement, window installation, sealing, shading and material choices all need to match the approved documentation.

But as with architects, a builder should not be assumed to be a NatHERS assessor unless they are suitably trained or accredited for that role. Building the home and modelling the thermal performance are different responsibilities.

A builder can help confirm what is practical to construct, while the assessor can confirm how the chosen specifications affect the thermal star rating.

What software does a NatHERS assessor use?

NatHERS assessments are prepared using accredited residential energy rating software. The software models the proposed dwelling and estimates the heating and cooling energy needed to maintain comfort in the relevant climate zone.

Different assessors may use different accredited tools, but the purpose is the same: to calculate a thermal star rating that reflects the design, construction and location of the home.

At Certified Energy, NatHERS assessments are supported by experienced assessors using industry recognised tools such as AccuRate, HERO and BERS Pro where appropriate for the project.

What makes a good NatHERS assessor?

A good NatHERS assessor does more than produce a number. They help the project team understand what is influencing the rating and what information is needed for a clear, reliable assessment.

This is especially important when a design is close to the required rating, when documentation is incomplete or when the project involves complex conditions such as raked ceilings, exposed floors, large glazing areas, multiple dwellings or challenging orientations.

The assessor should be able to communicate clearly with architects, builders, homeowners, developers and certifiers so the final documentation remains consistent with the assessment outcome.

Why communication matters

A NatHERS assessment often involves coordination. The assessor may need to clarify window details, insulation locations, construction systems, shading dimensions, roof colour or floor construction before the final result can be issued.

Clear communication can reduce delays and help avoid assumptions. It can also help the project team understand whether the rating is affected by a design issue, specification issue or missing documentation.

This is especially valuable when the project is approaching lodgement or when late changes may affect the compliance pathway.

How assessors work with project teams

A NatHERS assessor may work with architects, building designers, builders, developers, homeowners, certifiers and other consultants. The exact coordination depends on the project type and approval pathway.

On a simple home, the assessment may be relatively straightforward. On a complex project, the assessor may need to help test options, review revised documents and align the final rating with BASIX, 7 Star, Whole of Home or other project requirements.

For more detail on the process, see our guide to what a NatHERS assessment is.

What should you provide to the assessor?

The assessor needs enough information to model the home accurately. This usually includes architectural drawings, site orientation, construction details, insulation values, window schedules, glazing details, shading information and roof colour details where known.

Providing clear information early helps reduce assumptions and back and forth. It can also make it easier to identify whether the design is likely to meet the required rating before the project is fully locked in.

For a focused checklist, see our guide to what documents are needed for a NatHERS assessment.

How assessor choice connects to compliance

Choosing the right assessor can affect how smoothly the compliance pathway is resolved. A well prepared assessment can help reduce uncertainty around the star rating, documentation commitments and required design changes.

For many projects, NatHERS may connect with 7 Star Rating, Whole of Home and state based pathways such as BASIX in NSW.

The assessor should understand how NatHERS fits into that broader pathway, rather than treating the star rating as an isolated number.

Design considerations for Australian homes

Australian homes vary widely by climate, site, construction method and approval pathway. A good NatHERS assessor needs to understand that a design response for one climate or state may not suit another.

The assessment should reflect the home’s actual context: its climate zone, orientation, building fabric, window strategy, shading, roof form, floor construction and intended documentation pathway.

This helps the final rating become more than a compliance result. It becomes a clearer picture of how the home is expected to perform thermally.

Working with Certified Energy

Certified Energy provides NatHERS assessments for new homes, townhouses and multi residential projects across Australia. Our team includes experienced residential energy assessors who can model the home and help connect the rating with the relevant compliance pathway.

We can help project teams understand what information is needed, whether the design is likely to meet the required rating and what changes may be needed if the first result is too low. We also support related pathways including NatHERS, BASIX, 7 Star Rating and Whole of Home.

For the broader assessment framework, visit our NatHERS Knowledge Hub.

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