NatHERS 7-Star Rating for New Residential Builds (AU)

What it is

NatHERS is the Nationwide House Energy Rating Scheme. It rates the thermal performance of a residential dwelling on a 0 to 10 star scale, where higher stars mean less energy needed to keep the home at a comfortable temperature. NCC 2022 Volume Two raises the minimum thermal performance for new Class 1 buildings from 6 stars to 7 stars.

The 7-star figure relates to the envelope only. Floors, walls, ceilings, roof, glazing, orientation, shading and air-tightness are modelled in software. Mechanical systems, appliances and PV are assessed separately under the new Whole-of-House provisions in NCC 2022 Part H6.

How NatHERS works

Accredited assessors and Chenath engine

A NatHERS rating is produced by an accredited assessor using software that runs the federal Chenath calculation engine. Three software tools are accredited in 2026: AccuRate, FirstRate5 and BERS Pro. Each produces a NatHERS Universal Certificate that documents the rating, the climate zone, the assumptions and the assessor identifier.

The assessment is climate-zone specific. Australia has eight NatHERS climate zones based on heating and cooling degree days. A house that hits 7 stars in Hobart will not necessarily hit 7 stars with the same envelope in Darwin. Builders working across multiple climates need an assessor who understands the trade-offs.

What a 7-star rating actually requires

To hit 7 stars on a typical Class 1 build the assessor will usually need a combination of better glazing (often double-glazed in southern climates), more wall and ceiling insulation than the old 6-star baseline, attention to thermal bridges, controlled shading on north and west elevations, and a tighter building envelope around the conditioned spaces.

The rating tolerates trade-offs. A house with poor orientation can still reach 7 stars with upgraded glazing and insulation, but the cost premium is real. Best practice is to model early in the design phase so the building shape supports the rating rather than fighting it.

State and territory adoption

NCC 2022 was published in October 2022 and adopted at different times across the states. Most jurisdictions transitioned during 2023 and 2024 with practical effect on building permits issued from May 2024 onwards. South Australia and other states applied transitional arrangements for projects already in design. Builders should check their state regulator for the cut-off date that applies to their specific permit.

Climate zone matters

Class 1 buildings in cold climate zones (zones 6, 7 and 8) often need additional insulation and condensation management to reach 7 stars without creating moisture risk. NCC 2022 Part F8 condensation management provisions interact directly with the higher insulation needed for the rating.

How TradeLens checks this

TradeLens flags a Class 1 building permit where the NatHERS Universal Certificate is missing, the rating is below the applicable state minimum, the assessor identifier is not on the current accredited list, or the as-built construction does not match the modelled assumptions for insulation R-values, glazing or shading.

Common compliance gaps

The recurring gaps are envelope changes made on site without re-rating, missing assessor sign-off on glazing substitutions, ceiling insulation R-values lower than modelled, and incomplete documentation of fixed external shading that the rating depended on.