Performance Solutions for homes · NCC Volume Two
It’s not a loophole. It’s in the Code.
The National Construction Code’s heating and cooling requirement for houses can be met by a Deemed-to-Satisfy Solution or a Performance Solution. A NatHERS rating is one option inside the first. H6V2 is the Code’s own way of verifying the second.
01What the rules actually say
| What many people assume | What the rules say | Source |
|---|---|---|
| “NatHERS 7 stars is the only way to comply.” | The Performance Requirements are the mandatory part of the NCC. They are met by a Performance Solution, a Deemed-to-Satisfy Solution, or a combination. For a house, a NatHERS rating is one Deemed-to-Satisfy option for heating and cooling; the elemental provisions are another; H6V2 verifies a Performance Solution. | A2G1(2) H6D2 H6V2 |
| “Seven stars is the gold standard.” | Seven stars is the minimum for the NatHERS route in most states, and lower in climate zones 1 and 2 with a qualifying outdoor living area. The ABCB says “all compliance options aim to offer an equivalent level of performance”. | ABCB handbook (2024) pp 10, 111 |
| “A Performance Solution is a loophole.” | It carries more process, not less: a performance-based design brief prepared with stakeholders, analysis, evaluation against acceptance criteria, and a final report. WA’s regulator says it “is not a mechanism for accepting non-compliance … rather it is a pathway for demonstrating compliance”. | A2G2(4) WA Industry Bulletin 102 |
| “The surveyor won’t accept it.” | Building surveyors and certifiers assess Performance Solutions as part of building approval in every state. In WA, for example, the registered building surveyor approves one when issuing the Certificate of Design Compliance. Involving the surveyor in the design brief is how acceptance is won. | WA Industry Bulletin 102 Building Regulations 2012 r 16(3)(c) |
02The routes, compared
Same requirement. Different benchmarks.
Each route asks a different question of the same house. Which one costs least depends on the design, which is why we compare them before anything is specified.
| Attribute | NatHERS rating | Elemental provisions | Performance Solution (H6V2) |
|---|---|---|---|
| Type of solution | Deemed-to-Satisfy | Deemed-to-Satisfy | Performance Solution, verified by an NCC Verification Method |
| Benchmark | A fixed star band for the climate zone, corrected for floor area | A prescribed value for each element | A reference version of the same house, built to the Deemed-to-Satisfy Provisions of Parts 13.2, 13.3 and 13.5 |
| Heating and cooling | A star band, plus separate heating and cooling load limits in most states. WA’s variation removes the separate limits | Not modelled | Each tested separately against the reference in climate zones 2 to 7 |
| Calculation | Accredited NatHERS software | None | A method complying with ANSI/ASHRAE Standard 140. House energy rating software can’t be used |
| With Thermarate | Rated in-house by our accredited assessors | Checked against each provision and documented | Modelled, documented and agreed with your surveyor |
| Star certificate | Yes | No | No. Our accredited assessors can provide a NatHERS rating on request |
| Often suits | Designs that reach the band without costly upgrades, or where a star certificate is needed | Straightforward designs that meet every prescribed value as drawn | Designs where reaching the star band means a long or costly upgrade list |
Stricter, not looser. In climate zones 2 to 7, an H6V2 Performance Solution must match or beat the Code’s reference house on heating and on cooling, each separately. In WA, where the NatHERS route is judged on combined heating and cooling, that makes H6V2 the stricter test.
03How H6V2 works
Two models of the same house. Two tests.
- Model your designThe house as drawn, under the operating schedules, thermostat settings and occupancy the NCC prescribes, through every hour of a typical year.
- Model the referenceThe same house again, built to the Deemed-to-Satisfy Provisions of Parts 13.2, 13.3 and 13.5. Same floor plan, same windows, same assumptions. H6V2(2), H6V2(3).
- Compare, load by loadIf your design needs no more heating and no more cooling than the reference, it meets H6P1. In climate zones 2 to 7, each load is tested on its own. H6V2(1)(a)(iii).
Held the same in both models
- Calculation method
- Floor plan, including the size and location of glazing
- Ventilation
- Zoning and hours of occupation
- Heating and cooling schedules, and thermostat settings
- Occupancy, internal heat gains and air infiltration
Selected items from H6V2(3)(a)–(t).
Free to differ
- Insulation
- Glazing performance: Total System U-Value and SHGC
- Shading
That is why it can cost less: the design is upgraded where it needs to be, not to reach a star band.
04What the method requires today
The method has a history. Here’s what it requires now.
An older version of the reference-building method, often called VURB, was used widely, including in WA, and in 2017 it was reported as a way to pass houses well short of the standard. The ABCB tightened it in NCC 2019 and again in NCC 2022. We think that history should be answered, not avoided.
- The reference house must comply with the Deemed-to-Satisfy Provisions of Parts 13.2, 13.3 and 13.5H6V2(2)
- House energy rating software can’t be used; the calculation method must comply with ANSI/ASHRAE Standard 140H6V2(1)(a), H6V2(4). Barred for this method since NCC 2019 Amendment 1 (in WA, from 1 May 2021).
- Operating schedules, thermostat settings and occupancy are prescribed, and the same in both modelsH6V2(3)
- Heating and cooling are each tested against the reference in climate zones 2 to 7H6V2(1)(a)(iii)
- Climate data must be hourly and representative of a typical yearH6V2(5)
- We agree the design brief, including every reference assumption, with your surveyor before modellingA2G2(4)(a)
05From plans to permit
A check first. Then the full process.
Every engagement starts with a Pathway Check. If a Performance Solution is the better route, the process below takes the design from plans to an approved permit.
- 01
Pathway Check
You send plans, elevations, specification and location, plus any NatHERS report or upgrade quote you hold. We tell you which route is likely to cost least, and the upgrades each route needs.
- 02
Your decision
If NatHERS or the elemental provisions suit your design better, we say so. Stay with your own assessor, or have our accredited assessors deliver it.
- 03
Design brief
We prepare the performance-based design brief with your building surveyor: what is compared, which assumptions apply, and what counts as a pass.
- 04
Model and test
Two models, proposed and reference, with sensitivity checks on the assumptions that matter most, and an independent review of both.
- 05
Report
A final report setting out the analysis, the results and any conditions or limitations, ready for the surveyor’s assessment.
- 06
Approval
Your building surveyor or certifier approves the Performance Solution as part of the building approval.
- 07
Verify the build
An insulation check at handover, and a re-check of any product substitutions against the model, so the house performs as modelled.
06Scope
What H6V2 covers.
H6V2 verifies heating and cooling, Performance Requirement H6P1. Whole-of-home energy, H6P2, is met separately, through the Deemed-to-Satisfy Provisions or a NatHERS Whole of Home rating, and solar panels can’t make up for the building fabric. We’ll tell you which suits.
Where it applies.
We work with clients across Australia. H6V2 is part of NCC Volume Two; New South Wales uses BASIX instead, and some states and territories vary the energy provisions. We’ll confirm what applies to your site before you commit.
07Questions
Fair questions, straight answers.
Isn’t this a loophole?
No. The NCC lists a Performance Solution as one of its ways to comply, and H6V2 is a Verification Method written into the Code itself. The older method was misused, including in WA; the ABCB tightened it in NCC 2019 (in force in WA from 1 May 2021) and again in NCC 2022, and we agree every reference assumption with your surveyor before the compliance modelling. And in climate zones 2 to 7, heating and cooling must each be no worse than the reference, which in WA makes it stricter than the NatHERS route.
Why does it cost more than a rating?
Because it is more work: two full models, a design brief agreed with your surveyor, sensitivity checks and a formal report. Compare the total, not the fee. A Performance Solution pays for itself when the upgrades it removes cost more than it does, and the Pathway Check shows whether that is likely for your design before you commit.
We’re happy with our energy assessor.
Keep them. Send us the one job where the upgrade list hurts. Your assessor still does your NatHERS work, and we’re happy to work alongside them.
Will my surveyor accept it?
Building surveyors and certifiers assess Performance Solutions routinely, in every state. We prepare the design brief with yours before any compliance modelling, so the assumptions are agreed up front. The NCC requires a design brief for every Performance Solution. In WA, the registered building surveyor approves it when issuing the Certificate of Design Compliance.
Is the house less efficient than a 7-star house?
By the Code’s measure, no: its modelled heating and cooling loads are no higher than those of the Deemed-to-Satisfy version of the same house, which is what H6P1 requires. Rated with NatHERS, some designs might score below 7 stars, so we don’t claim a star equivalent.
Does it cover whole-of-home energy?
No. H6V2 covers heating and cooling (H6P1). The whole-of-home energy requirement (H6P2) is met separately, through the Deemed-to-Satisfy Provisions or a NatHERS Whole of Home rating. If a Whole of Home rating is used, check how its thermal star rating will read to buyers and lenders. We’ll say which route suits.
Will my client need a star rating for a loan or a sale?
Sometimes. Some green home loans have required a NatHERS certificate of at least 7 stars, and rating disclosure at sale is growing. A Performance Solution has no star certificate, so where it matters, our in-house accredited assessors can provide a NatHERS rating on request.
Is H6V2 being phased out?
No. NCC 2025 keeps it, and residential NCC changes are paused until mid-2029 other than essential quality and safety measures. More in NCC 2025: what changes for your homes?
Does it take longer?
There is one extra step: agreeing the design brief with the surveyor. We start it on day one.
What if the design changes?
We re-run the models, as an assessor would re-run a rating. A material change may need the surveyor’s agreement again.
Why trust you? Don’t you sell Performance Solutions?
Fair question. We don’t only sell Performance Solutions: we also have Australia’s largest team of in-house NatHERS accredited assessors, so we have no reason to push one route. The Pathway Check tells you which suits your design, and our method and assumptions are written down for your surveyor to check.
Don’t models miss how houses are really built and used?
Yes. Every compliance model does, ours included, and both routes use standard assumptions. If real-world performance matters, test the finished house. We can do that too.
Pathway Check
Find out which route suits your design.
Send plans and any NatHERS report you already hold. We’ll compare the routes and tell you which is likely to cost least, including when the answer is NatHERS.