Energy assessor (NatHERS)
A NatHERS energy assessor models a home's thermal performance in approved software before construction, producing the report that sets its glazing and insulation.
Ask Chalkline about this →An energy assessor (a NatHERS assessor) is an accredited professional who models a dwelling’s thermal performance in approved software before construction and produces the report that drives insulation and glazing selection to hit the required star rating.
They are accredited through a NatHERS Assessor Accrediting Organisation and work in approved tools such as AccuRate, FirstRate5, or BERS Pro. The job is straightforward in outline: take the architectural plans, model the building’s fabric and orientation, and output two things, the star rating (the certificate the building approval needs) and the specification required to achieve it, the ceiling, wall and floor insulation R-values, and the glazing performance (U-value and SHGC).
Since NCC 2022, new homes must reach a minimum 7 stars under NatHERS, alongside a separate whole-of-home energy budget, so the assessor’s output sets a meaningful part of the build spec, not just a compliance tick.
For a builder the practical rule is to bring the assessor in at design, not after the windows are ordered. Their report dictates the glazing and insulation, and a change made after assessment, bigger windows, a different orientation, a deleted eave, can drop the stars and force a re-spec or a re-rate. Build to the stamped plans and specification, because the certificate is exactly what the certifier checks against the finished house. If you value-engineer the glazing or insulation on site without telling the assessor, you risk failing the energy provisions at occupancy.
Also known as: NatHERS assessor, thermal performance assessor.
Category: Energy / Assessment.
Related
See also
References
- Nationwide House Energy Rating Scheme (NatHERS) (verified 2026-06-01)
Last updated: 2026-06-01. Verified: 2026-06-01. Quarterly review for currency.