The Architects Guide to Energy Efficiency: Navigating Alterations & Additions under NCC 2022 in South Australia
South Australia has seen a surge in alteration and addition projects in recent years. At ARKATA, roughly one in every four projects falls into this category. This trend is understandable—homes are expensive, land near the CBD is scarce, and as a result, many homeowners are choosing to enhance their existing homes rather than relocate. Given this, understanding how to navigate alterations and additions under NCC 2022 is crucial.
Understanding NCC 2022’s Impact on Existing Homes
The introduction of NCC 2022 brought significant changes, including the 7-Star requirement and Whole of Home provisions. These updates present both challenges and opportunities. While achieving 7-Stars or above is feasible for new builds, the same isn’t always realistic for alterations and additions. To navigate this, early engagement is essential, before planning approval it’s important to assess the home’s performance, explore potential upgrades, and determine the best compliance pathway as soon as possible.
This article will explore the compliance pathways available for alteration and addition projects in South Australia. If you’re in Victoria, a version tailored to your state will be available in a future edition of Thinking Forward.
For a broader understanding of compliance requirements, The Architects Guide to Energy Efficiency: Navigating Compliance Pathways for Part 13.2 of NCC 2022 provides an in-depth look at all projects' obligations under NCC 2022. If needed, refer to that guide before continuing.
Compliance Pathways for Alterations and Additions
Ahead of the October 2024 transition to NCC 2022, South Australia introduced the Ministerial Building Standard MBS 013: Application of NCC modern homes provisions to existing Class 1 buildings. Although still in draft form as of 12 September 2024, it is scheduled to take effect on 1 May 2025 (as detailed under PlanSA’s NCC 2022 modern homes provisions).
Deemed to Satisfy (DTS) Provisions
MBS 013 outlines the DTS provisions for compliance. These align with NCC 2022’s energy efficiency requirements:
13B1P1 → Equivalent to H6P1 (Thermal Performance / Star Ratings)
13B1P2 → Equivalent to H6P2 (Energy Usage / Whole of Home)
To satisfy these requirements:
For alterations: Compliance with 13B1P1 (Thermal Performance) is achieved by following 13B2D3 (Energy Efficiency Provisions).
For additions increasing habitable floor area by 50% or less, compliance can be achieved by:
NCC 2022 ABCB Housing Provisions: Part 13
MBS 013: Section B (Energy Efficiency)
Using NatHERS and meeting the DTS provisions outlined in 13B2D2(1)(b)(iii) A–F (covering insulation, thermal breaks, building sealing, etc.)
For additions exceeding 50% of habitable floor area, compliance must be achieved by:
NCC 2022 ABCB Housing Provisions: Part 13
MBS 013: Section B (Energy Efficiency)
Additionally, 13B1P2 (Energy Usage) applies only when all domestic services are being replaced. If they are, compliance must be demonstrated through:
MBS 013: Parts 1.5 (Whole of Home) & 1.6 (Services)
NCC 2022 ABCB Housing Provisions: Parts 13.6 (Whole of Home) & 13.7 (Services) (for homes ≤ 500m²)
Performance Solution
A performance solution may also be used, with relevant requirements determined under MBS 013: 13A2A2 and 13A2A4.
Methods of assessment include:
Evidence of suitability (NCC 2022: Part A5)
Expert judgement
Comparison with DTS Provisions (most commonly used and aligned with NCC 2019s V2622 and NCC 2022’s H6V2)
While verification pathways will be explored in a future article, it’s important to note that using a performance solution does not inherently show compliance with 13B1P2 (Energy Usage)—the ABCB Whole of Home calculator must be used.
Breaking Down the 50% Rule
Any addition increasing the habitable floor area by more than 50% must comply with either:
NCC 2022 ABCB Housing Provisions (Part 13.2)
MBS 013 Section B Energy Efficiency Requirements
This means projects exceeding an increase in the habitable floor area by more than 50% cannot use NatHERS for compliance.
For additions below 50%, NatHERS remains an option, with the inclusion of star rating discount (Specification 01) process.
Floor area examples
These examples highlight that most architecturally-focused additions will exceed the 50% limit, restricting their ability to use NatHERS as a final compliance pathway.
The ARKATA Way: Thinking Forward
Given the complexities of NCC 2022 and MBS 013, ARKATA is refining its approach:
Previously: We treated alterations & additions like new homes, optimising first and then finding the compliance pathway.
Now: We first determine the compliance pathway, using the minimum requirements as a baseline before optimising the entire home (new and old) within NatHERS. If NatHERS reveals itself as an option for compliance, it simplifies the compliance solution significantly.
Our NatHERS-first approach ensures we help architects deliver homes that are healthy, comfortable, and resilient while maintaining flexibility in the compliance approach.
Final Thoughts
The inability to use NatHERS for projects exceeding 50% of habitable floor area is disappointing—it could streamline compliance while improving outcomes.
For example, two of the projects shown in the floor area examples above were following ARKATA’s 3-step process and achieved exceptional results: one saw its whole-of-home star rating improve from 1.9 Stars to 4.1 Stars, with significant gains in the thermal comfort of the existing home. This effort should be rewarded with compliance, if we were able to show, using NatHERS, an improvement across the entirety of the dwelling.
Moving forward, energy efficiency within the architectural process needs to be proactive, not reactive, where engaging early means better project outcomes and fewer compliance headaches.
Always Remember: Early engagement with energy efficiency leads to better outcomes, fewer compliance frustrations, and ultimately, healthier homes.