A modular home's NatHERS rating is not a score for the product in every location. It describes the modelled thermal performance of a particular design. Before accepting a supplier's claim, check which plans, site and specifications were assessed.
The short answer
A higher star rating generally means a design needs less heating and cooling in its assessed climate. It does not establish structural compliance, approval for habitation or the quality of every fitting.
Ask for the assessment behind the number, not just a brochure badge. For the wider approval process, read what Class 1a means.
Star rating and Whole of Home are different
The official new-home energy rating guidance distinguishes thermal performance from whole-home energy performance.
| Assessment | What it describes | What to check |
|---|---|---|
| Star rating, out of 10 | Modelled heating and cooling needs of the building design | Climate, orientation, glazing, shading and insulation |
| Whole of Home, on a 0-100+ scale | Modelled energy performance including systems and onsite generation | Appliance specifications, solar and battery assumptions |
A strong thermal result does not, by itself, establish the second result. Nor does either number guarantee your actual electricity bill.
Does every new modular home need seven stars?
The official certificate guide describes seven stars and a Whole of Home score of 60 as the current minimums in most jurisdictions.
That wording matters: it is not a universal rule for every product, building class or application. Ask the assessor and certifier which energy-efficiency pathway, state provisions and transition rules apply to your project.
Check the approval starting point in our NSW guide or Victoria guide. Do not assume that a portable studio, expandable unit and permanent house share the same classification.
Five things to request before ordering
- 01The assessed floor plan and revision number.
- 02The site location, orientation and climate assumptions.
- 03The specified insulation, glazing and shading details.
- 04The Whole of Home result and its appliance assumptions, where applicable.
- 05The assessor's details and the certificate relevant to the final design.
Keep these documents with the written inclusions. If a quote substitutes windows, insulation or equipment, ask whether the assessment needs updating before accepting the change.
Factory manufacture does not guarantee a rating
Offsite manufacture does not automatically make a home seven-star or more efficient than a site-built home. Performance still depends on the design and the completed installation.
Ask how insulation continuity, seals and module connections will be checked. Clarify who verifies onsite junctions, service penetrations and any substitutions after delivery.
For broader checks, see our modular home structural standards guide. An energy assessment is one part of the evidence, not a substitute for engineering or building approval.
Comparing two supplier claims
Compare assessments for equivalent sites and specifications. A display-home result from another climate or orientation is not enough to establish the result for your project.
Use a short comparison sheet: plan revision, site assumptions, thermal rating, Whole of Home result and included equipment. Mark missing evidence as awaiting confirmation rather than treating it as a pass.
The permanent-home collection can help shortlist formats. Confirm project-specific evidence before treating any catalogue model as compliant for your land.
Frequently asked questions
Does a modular home's NatHERS rating apply to every site?
No. Check the assessed design, climate, orientation and specifications for your proposed site. A result for a display home or another location does not automatically establish the result for your project.
Are modular homes automatically seven-star homes?
No. Construction method alone does not establish an energy rating. Request the assessment and confirm that its plans and specifications match the home you intend to order.
Is the star rating the same as Whole of Home?
No. The star rating assesses thermal performance. Whole of Home also considers energy systems and onsite generation. Ask which assessments your project requires and check both results where applicable.
Does a higher rating guarantee lower electricity bills?
No. It is a modelled result, not a bill guarantee. Actual costs depend on use, weather, installed equipment, energy tariffs and how closely the completed home matches the assessed design.
Next steps
Start your Planning Assessment with the proposed site, intended use and product shortlist.
This is general information, not legal, planning or compliance advice. Confirm requirements with the relevant authority and qualified project professionals before making a commitment.
Sources and further reading
Requirements change and can be applied differently by site and local authority. Check the current official sources and confirm your project with the relevant council, certifier or qualified professional.