The Architects Guide to Energy Efficiency: Navigating Compliance Pathways for Part 13.2 of NCC 2022
Across the National Construction Code, there are always multiple pathways in achieving compliance, but, as we move forward, it is critical to understand each of the pathways available for Energy Efficiency within the NCC and the influence they have on project performance and outcomes for your clients.
In this article we will be looking into the three methods available for compliance against the National Construction Code (NCC) 2022 for Part 13.2: Energy Efficiency.
Remember, there are nuances, concessions, and regulatory differences across states and even suburbs. It’s essential to consult your energy efficiency consultant to understand how the code applies to your particular project/s.
The Objective of Part 13.2
Part 13.2 of the NCC 2022 has a clear set of objectives:
Reduce energy consumption and energy peak demand; and
Reduce greenhouse gas emissions; and
Improve occupant health and amenity.
To achieve this, buildings must:
Reduce the energy consumption and energy peak demand of key energy using equipment; and
Reduce greenhouse gas emissions that occur as a result of a building’s energy consumption and energy source; and
Improve occupant health and amenity by mitigating the impact of extreme hot and cold weather events, and energy blackouts.
Starting with these objectives in mind reminds us that compliance is not just about ticking boxes, but striving for meaningful performance and outcomes for the clients you serve.
Understanding H6P1 and H6P2
Compliance with Part 13.2 requires meeting two main performance components:
H6P1 (Thermal Performance): Think star ratings, minimum insulation levels, and thermal fabric performance
H6P2 (Energy Usage): Think whole of home, appliance efficiency, and solar integration
To comply with Part 13.2, projects must meet the requirements for both H6P1 and H6P2 separately and we have three main pathways to achieve this.
NatHERS Star Rating & Whole of Home
Covering your requirements for both H6P1 and H6P2
Elemental Deemed to Satisfy
Covering your requirements for both H6P1 and H6P2
Verification Using Reference Building (Performance Solution)
Only covering your requirements for H6P1
Figure 1: Simplified overview of compliance options within Part 13.2 of NCC 2022 Vol 2
NatHERS Star Rating & Whole of Home
The National House Energy Rating Scheme (NatHERS) is a government-backed scheme that takes a holistic approach, assessing the interplay of building elements (floors, walls, roofs, and windows, for example) and calculating heat flows.
Accredited vs Non-Accredited Assessors:
Accredited assessors are registered, insured, audited, and required to complete ongoing professional development. They adhere to a Technical Note that ensures consistency and quality across assessments.
Non-accredited assessors may still issue reports accepted by certifiers in some states but do not meet the same professional standards. This variability underscores the importance of choosing an accredited assessor for accountability and assurance.
NatHERS covers both H6P1 and H6P2, and provides data-rich insights invaluable for designing homes that are healthy, comfortable, and resilient.
Figure 2: Internal Temperature Comparison of 7-Stars vs 10-Stars
For architects looking to enhance project outcomes, and provide their clients with invaluable insights that empower greater, more informed decision making ability, the NatHERS pathway is the most informative and comprehensive choice, no matter the star rating target.
Elemental Deemed to Satisfy (DTS)
The Elemental Deemed to Satisfy approach is prescriptive, focusing on clear minimum requirements that must be met. This pathway is straightforward: if the design meets or exceeds these standards, compliance is achieved. However, it does not provide performance data or insights valuable for future optimisation.
Using an example to illustrate, Figure 3 shows the minimum insulation R-Value for a masonry veneer wall within Climate Zone 5.
There are a few notable items here worth considering.
These requirements reference minimum insulation R-Values, not Total R-Values of the wall construction. This is a change from NCC 2019.
Consider the Solar Absorptance, or SA, within the first column, where we only reach a maximum of 0.7. This means walls darker than 0.7 within Climate Zone 5 are not allowed.
For example, if you have designed a Colorbond Monument external wall, you will have to utilise the NatHERS or Verification pathway to achieve compliance with Part 13.2.
There are some instances across the varying climate zones where wall insulation exceeds R2.7 and, the possibility of walls being excluded entirely, with an “X”
The “Overhang” column shows a maximum allowance of 1500mm depth, resulting in a design not complying with eaves/verandahs exceeding 1500mm
Note: these exclusions and limitations vary depending on the Climate Zone
Figure 3: Minimum insulation R-Value for Climate Zone 5
With the shift from NCC 2019 to NCC 2022, DTS has become more prescriptive, potentially restricting your design flexibility. DTS may limit facade colour choices, materiality, or have wider reaching design consequences, ultimately impacting your architectural intent - something you do not want to uncover at the end of your construction documentation process. Projects not aligning with these new measures will need to switch to the NatHERS or verification pathways to show they’re still achieving the objectives set by the NCC.
DTS is typically used for alterations, additions, or projects that fall outside the NatHERS framework, such as smaller studios, or mixed building classifications. It could be expected that simpler, more standardised forms of home design, such as high-volume and/or catalogue homes, would continue to utilise this compliance pathway.
It’s worth noting that other states have been reporting difficulty with alterations and additions using the Elemental Deemed to Satisfy pathway, however, to aid with this, South Australia particularly are bringing in MBS 013 in May, purpose built for alterations and additions. More to come on this in the near future but refer to the “Additional Reading” below.
Verification Using Reference Building
The Verification Using Reference Building method is complex and requires specialised software. It’s also important to note that verification achieves compliance for H6P1, but not H6P2, meaning an additional method, such as DTS, is needed to complete the remaining compliance requirement concerning energy usage.
The building must show that its heating, cooling, and annual thermal energy loads are equal to or less than those of a reference building. NCC 2022 has updated the modelling requirements for the reference building, adding complexity when comparing it to the simpler tables used within NCC 2019. Ultimately, this change in the underlying calculations has brought the verification pathway up to par with the other compliance methods.
It’s worth noting that historically, some states, such as Victoria and New South Wales, have not accepted performance solutions like Verification Using Reference Building as a pathway to show compliance with the energy efficiency component of the NCC. However, in some instances, some certifiers accept the pathway when it has been completed by registered building practitioners such as engineers.
Are all things equal?
Historically, these compliance pathways were not equal. Specifications needed to meet DTS or verification were often a lot lower, or a little higher, than those for 6-Star compliance, depending on the project. In NCC 2022, these discrepancies have largely been balanced, making the choice between methods more about project suitability than simply specification cost.
However, not all methods are equal when it comes to the quality of assessments and outcomes. For example, the difference between accredited and non-accredited assessors using NatHERS remains significant. Always opt for accredited assessors for a reliable and insured outcome.
What method should you choose?
Choosing the right method depends on the value and service you wish to provide. Is energy efficiency a priority for you and your client? Do you aim to create high-performance, future-ready homes? If so, NatHERS is your most powerful tool, offering insights that go beyond simple compliance.
For simpler, or segmented projects, DTS or verification may suffice, especially when focusing on compliance with minimal data output.
Your Path Forward
Choosing a compliance method is a reflection of your project’s ambition, your clients’ priorities, and your practice’s dedication to sustainable, forward-thinking design. Each pathway comes with unique strengths and limitations, and understanding these can mean the difference between merely meeting minimum standards, or truly enhancing the project’s performance.
Consider what your project aims to achieve: Is it about meeting today’s standards efficiently, or is it about creating a home that seeks to enhance your clients health, comfort, and resilience well into the future?
Additional Reading
Ministerial Building Standard 013
NCC 2022 Housing Provisions
NCC 2022 Volume 2 Energy Efficiency Handbook