NatHERS Energy Rating Requirements for New Dwellings

What This Requirement Covers

The NatHERS (Nationwide House Energy Rating Scheme) energy rating requirements in the National Construction Code (NCC) set minimum thermal performance and whole-of-home energy targets for new dwellings in Australia. These requirements exist to reduce energy consumption for heating and cooling, improve occupant comfort, and lower greenhouse gas emissions by ensuring new homes meet a quantified thermal performance benchmark calculated with accredited house energy rating software.

The rules apply primarily to new Class 1 buildings (detached houses and townhouses) and associated Class 10 parts (carports, garages, sheds) where the NCC Volume Two Deemed-to-Satisfy pathway or the ABCB Housing Provisions are used to demonstrate compliance. They require both a minimum NatHERS star rating for the dwelling shell and compliance with specified heating and cooling load limits and whole-of-home energy usage limits.

Key Requirements

1. Minimum star rating: A building must achieve an energy rating of 7 stars or greater using accredited house energy rating software, including compliance with separate heating and cooling load limits, as specified in NCC Volume Two, Specification S42C2 (S42C2(1)).
2. Climate zone relaxations: For buildings in Climate Zones 1 or 2 the following alternative minima apply (S42C2(1)):
3. 6.5 stars where the building has an outdoor living area that is fully covered with an impervious roof having a Total R-value ≥ 1.5 (downward heat flow) (see S42C2(1)
4. (b) and S42C2(3)).
5. 6.0 stars where the building is in Climate Zones 1 or 2 and the outdoor living area (as above) also has at least one permanently installed ceiling fan (S42C2(1)(c)).
6. Outdoor living area definition and dimensions (S42C2(3)):
7. Must be directly adjoining and directly accessible from a general purpose living area (lounge, kitchen, dining, family) - not a sleeping room or specialist task room.
8. Minimum floor area: 12.0 m2.
9. Minimum length and width: 2.5 m each.
10. Opening height above floor level: ≥ 2.1 m.
11. One side must be permanently open and the second side must be either permanently open or readily openable (S42C2(3)(e)).
12. Heating and cooling load limits: The separate heating and cooling load limits required for the rating are those in the ABCB Standard for NatHERS Heating and Cooling Load Limits (referenced in S42C2(2)).
13. Whole-of-home energy usage: A building must achieve a whole-of-home rating of not less than 60 using house energy rating software, as required by NCC Volume Two, Specification S42C3.
14. Deemed-to-Satisfy additional provisions: To comply with Performance Requirement H6P1 using house energy rating software, a building must also comply with specified ABCB Housing Provisions clauses such as Part 13.2 (building fabric thermal insulation) and others listed in S42C4(1) (see NCC Volume Two S42C4).
15. Alternative elemental pathway: Compliance may alternatively be achieved by following Parts 13.2-13.5 (and 13.6-13.7 for whole-of-home where applicable) of the ABCB Housing Provisions instead of the house energy rating route (NCC Volume Two explanatory information and S42C4).
16. Relevant NCC references:
17. NCC Volume Two - Specification S42C2, S42C3, S42C4 (energy rating, whole-of-home, and additional Deemed-to-Satisfy provisions).
18. NCC Volume One - where applicable for sole-occupancy units in Class 2 buildings, see J3D3 and related clauses referencing house energy rating pathways (NCC Volume One J3D3, J3D4).
19. ABCB documents and Standards:
20. ABCB Standard for NatHERS Heating and Cooling Load Limits (for separate load limits referenced in S42C2(2)).
21. ABCB Housing Provisions Standard 2022 (Parts 13.x) for elemental Deemed-to-Satisfy provisions and whole-of-home factors (referenced in S42C4 and explanatory notes).
22. Where external standards apply to construction detailing that affects thermal performance, reference industry codes such as AS 1684 (timber framing) or other applicable Australian Standards for material and construction requirements as relevant to the building element design.

Residential vs Commercial

1. Residential (Class 1 and associated Class 10): The NatHERS requirements explicitly apply to new Class 1 dwellings via NCC Volume Two. The primary pathway is the house energy rating approach under S42C2-S42C4 or the ABCB Housing Provisions elemental pathway (Parts 13.x). The whole-of-home rating of ≥ 60 and the 7-star fabric rating (or permitted relaxations for Climate Zones 1 and 2 with outdoor living areas) are targeted at these residential building classes.
2. Commercial / Multi-residential (Class 2-9): NatHERS star ratings do not directly apply to typical commercial building classes. However, for sole-occupancy units of Class 2 buildings and Class 4 parts the NCC Volume One contains specific provisions requiring the use of house energy rating software to reduce heating and cooling loads and sets minimum averaged and individual ratings (for example J3D3 requires sole-occupancy units to collectively achieve an average of not less than 7 stars and individually not less than 6 stars, including load limits). In other words, multi-residential apartments are regulated under NCC Volume One housing provisions with similar but not identical requirements and additional clauses (J3D3, J3D4, etc.).

Exceptions and Exemptions

1. Climate zone relaxations (S42C2(1)(b)-(c)) permit lower star ratings in Climate Zones 1 and 2 when a qualifying outdoor living area is provided and meets the specified dimensions and thermal properties.
2. Alternative compliance via the ABCB Housing Provisions (elemental pathway) is permitted: instead of demonstrating a NatHERS star rating, a building may meet the detailed elemental Deemed-to-Satisfy provisions in Parts 13.2-13.7 where applicable (NCC Volume Two explanatory information and S42C4).
3. State schedule variations may create temporary or permanent additional exemptions or requirements (see the next section). Always check the relevant state schedule in the NCC for local variations before relying on a national-only interpretation (NCC Volume One and Volume Two state schedules).

State and Territory Variations

1. The NCC requires users to check state and territory schedules because jurisdictions may modify or add provisions that affect energy efficiency compliance. For example:
2. Victoria: The NCC Volume Two explanatory information references Victorian variations and clarifies that there are two Deemed-to-Satisfy pathways (Specification 42 energy rating pathway or the ABCB Housing Provisions elemental pathway). Victorian-specific variations such as rainwater tank requirements have previously been included in state schedules (see NCC Volume Two notes and VIC variations in the state schedules).
3. New South Wales: NCC Volume One includes J3D3-J3D4 which specifically apply to sole-occupancy units in Class 2 buildings; state-specific schedules (Schedules in Volume One) should be checked for additional NSW modifications.
4. All other states and territories may include schedule items (Schedules 4-12 in NCC Volume One) that alter, add to, or replace national provisions for energy efficiency. The NCC Volume Two and the ABCB Housing Provisions note that users must verify requirements against the relevant state schedule.

Practical Compliance Tips

1. Start NatHERS modelling early - engage an accredited NatHERS assessor at the schematic design stage so orientation, glazing, shading and insulation strategies are evaluated before detailed design decisions are locked in.
2. Use accurate inputs - modelling is sensitive to orientation, shading, glazing U-values and g-values, internal gains and occupancy patterns. Common errors include incorrect window sizes, omitted eaves or mis-specified external shading which can change the rating materially.
3. Consider outdoor living area strategy in hot climates - for Climate Zones 1 and 2 a correctly sized and constructed outdoor living area can allow lower star ratings (6.5 or 6.0 stars) but the roof Total R-value ≥ 1.5 and dimensional requirements must be met exactly (see S42C2(3)).
4. Verify separate heating and cooling load limits - ensure the NatHERS report demonstrates compliance with the ABCB Standard for NatHERS Heating and Cooling Load Limits as well as the overall star rating (S42C2(2)).
5. Meet whole-of-home energy usage - in addition to the fabric star rating, confirm the dwelling achieves a whole-of-home rating ≥ 60 (S42C3) when using house energy rating software; this often requires correct input for services and equipment efficiency.
6. Document Deemed-to-Satisfy choices - if following the elemental pathway (ABCB Housing Provisions Parts 13.x) keep clear records showing compliance with each clause called up by S42C4 to satisfy H6P1 and H6P2.
7. Check state schedules and local requirements early - don’t assume the national minimum applies universally; some states may have tighter minimums or extra requirements that affect energy compliance and documentation.

References: NCC Volume Two - Specification S42C2, S42C3, S42C4; NCC Volume One - J3D3; ABCB Standard for NatHERS Heating and Cooling Load Limits; ABCB Housing Provisions Standard 2022 (Parts 13.x). Could not answer: false