A prescriptive pathway to energy efficiency compliance for your extension, without thermal performance modelling.
Where an extension connects to an existing home, a NatHERS assessment brings the existing fabric into scope. If that fabric is uninsulated, single glazed or simply undocumented, reaching the star rating can become an exercise in upgrading parts of the house you were not intending to touch.
The Elemental Provisions pathway avoids this. Each component of the new work is assessed against a fixed benchmark set out in the ABCB Housing Provisions, and only the new work is considered.
The trade off is flexibility. There are no offsets between elements, so a generous window cannot be compensated for by better insulation elsewhere. Every element must meet its benchmark on its own. For extensions with modest glazing this is often the faster and cheaper route. For extensions with large glazed openings it rarely is, and NatHERS will usually serve you better.
Energy efficiency compliance for alterations and additions to Class 1 buildings under NCC 2025, via the Elemental Provisions in ABCB Housing Provisions Part 13, including the compliance report required for building permit approval. This includes assessment against Part 13.6, Whole of Home energy usage.
Each element of the proposed work is assessed against its prescribed benchmark: roof, ceiling, wall and floor insulation values, glazing performance by orientation under the conductance and solar admittance calculations, building sealing and thermal breaks.
Required by owners, architects and builders extending an existing home where the NatHERS pathway is not the preferred route. Accepted by building surveyors as an alternative means of demonstrating compliance.
Stage 1 — Project Initiation. Studio Bun reviews your drawings, specifications and brief, identifies the NCC 2025 requirements that apply to the project, and issues a proposed compliance pathway together with a fixed fee covering the full process.
Stage 2 — Preliminary Assessment & Design Advice. The proposed works are assessed element by element against the prescribed benchmarks. We issue a Preliminary Assessment Report setting out what is required for compliance. This stage identifies the key challenges to the project and the improvements available, whether to exceed compliance or to reduce the cost of meeting it.
Stage 3 — Design Iteration & Optimisation. Between the preliminary and final reports we allow two rounds of minor changes to the design, and a meeting to review the recommendations. From here we can focus on cost efficiency or on performance, as the project requires.
Stage 4 — Final Reporting. Once the final specification and design are documented, we confirm each element against its benchmark and issue the final compliance report for your building surveyor, alongside a stamped set of drawings. Changes after the final report is issued are charged at an additional rate, depending on the size and scope of the change.
Assessment of the proposed works against ABCB Housing Provisions Part 13
Whole of Home assessment under Part 13.6
Conductance and solar admittance calculations for glazing, by orientation
A preliminary report identifying which elements fall short and the options to correct them
Advice on the glazing and insulation specification required to satisfy the benchmarks
Two rounds of minor changes between preliminary report and finalisation
Specification schedules for insulation, glazing and sealing
A final compliance report for your building surveyor
A few items sit outside this scope and can be quoted separately:
Thermal performance modelling or a star rating (see NatHERS for residential extensions)
New dwellings (see Elemental Provisions for single dwellings)
Minor design changes beyond two rounds
Blower door and air permeability testing
Acoustic, daylight or mechanical assessments
BESS reports or SDAs
Stormwater management (available as its own service)
This service assumes an alteration or addition to a Class 1 residential building under NCC 2025, with PDF drawings of the existing dwelling and the proposed works sufficiently complete for assessment.
Studio Bun offers fixed sum packages for Elemental Provisions assessments, priced on the extent of the works and the number of elements requiring assessment.
Contact us for a quote.
Does my extension need energy compliance?
Generally yes. New building work on a home must meet the energy efficiency requirements of the NCC, and your building surveyor will require documentation demonstrating it. How the requirements apply depends on the scale of the works, and we confirm that in the Stage 1 review.
Should my extension use the Elemental Provisions or NatHERS?
The Elemental Provisions pathway is often well suited to extensions. It is quicker, more predictable, and avoids modelling an existing home that may have limited documentation. But extensions with generous glazing or unconventional construction can struggle under the prescriptive limits, where NatHERS gives more freedom. The Stage 1 review answers this for your specific project before you commit.
Do the requirements apply to the whole house or just the new works?
The provisions are focused on the new building work, though junctions with the existing fabric, and for larger extensions requirements affecting the wider home, need care. We confirm exactly what's in scope for your project up front.
What do you need from me to start?
Drawings of the existing dwelling and the proposed works in PDF, plus your specifications. If anything's missing for the assessment, we will flag it before we go further.
Send through your drawings for a fixed-fee quote.
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