Mandatory solar PV, tighter facade U-values and new J1V3 modelling requirements. Here is what changes under Section J from 1 May 2027 and what to address before your next CC lodgement.
NCC 2025 was made available for adoption from 1 May 2026. For commercial buildings in NSW, it applies to projects with a CC lodgement date on or after 1 May 2027, confirmed by NSW Ministerial release. Until then, NCC 2022 Amendment 2 governs all commercial Section J assessments. Always confirm the lodgement date in writing from the certifier before selecting which code version applies.
The changes are material. Architects, builders and surveyors designing for 2027 lodgement should understand what is coming well in advance.
NCC 2022 treated on-site solar PV as a J1V3 reference building concept, something modellers accounted for, not something DTS clients had to specify. NCC 2025 changes that entirely.
J9D5 now applies to all commercial buildings on the DTS pathway. Buildings must cover 100% of eligible roof area with solar PV, or achieve a minimum peak output relative to conditioned floor area. Minimum output requirements vary by climate zone and building class. For a Class 5 or Class 6 building in Sydney (Climate Zone 5), the indicative minimum is in the range of 65 Wp per m² of conditioned space (confirm exact value against the final J9D5 tables before design). Buildings using gas for services face an additional PV requirement on top of this.
The only exemptions are where 100% of the eligible roof area is shaded more than 70% of annual daylight hours, or where an equivalent renewable generation system is provided.
This requirement adds to project cost and requires early coordination with the electrical engineer and structural engineer. DTS compliance cannot be achieved without it from 1 May 2027.
The minimum total R-value for Class 5, 6, 7 and 8 in Climate Zone 5 remains, but NCC 2025 adds new conditions for solar reflectance and thermal emittance. Bare aluminium roofing, common in industrial and warehouse projects, may no longer satisfy the requirements on its own under NCC 2025. Aluminium has very low thermal emittance (around 0.05) and would need to achieve sufficiently high solar reflectance to comply independently. Confirm exact J4D4 thresholds against the final published clause before specifying metal roofing on NCC 2025 projects.
The total system U-value limit, which governs the combined performance of opaque wall and glazing together, is now climate-zone dependent rather than a flat value across all zones. For a Class 5 office in Climate Zone 5, the limit tightens from the NCC 2022 figure. Opaque wall R-values have been substantially revised and are generally tighter across multiple climate zones. Solar admittance limits have also been revised. Verify exact U-value limits and R-values against the final J4D6 tables before finalising glazing specifications for NCC 2025 projects.
These changes are most relevant to projects with high glazing ratios where the DTS facade calculator previously allowed more flexibility. Glazing specifications that passed under NCC 2022 may no longer pass under NCC 2025 without adjustment.
Projects using the performance pathway face additional changes under NCC 2025.
The reference building now includes a modelled solar PV system per J9D5, with the same minimum output as the DTS requirement. This changes the energy budget the proposed building must beat and means modellers need to account for PV generation in both models.
NCC 2025 introduces updated climate and weather file requirements for J1V3 modelling, based on 2050 RCP 8.5 projections. Standard historical TMY EPW files used under NCC 2022 may no longer be suitable for NCC 2025 assessments.
Energy modellers should confirm the required weather files early, as the selected file will affect heating and cooling loads, reference building performance and proposed building results.
NCC 2025 introduces a zone-by-zone peak load comparison, requiring assessable heating and cooling zones to be individually documented. This adds a meaningful step to the reporting process.
In NSW, the proposed building must achieve 97% or less of reference building GHG emissions. Confirm the exact national baseline and any NSW variation against the final NCC 2025 J1V3 provisions before reporting.
Section J addresses operational energy: the energy consumed by a building's HVAC, lighting, hot water and other services during its working life. NCC 2025 does not introduce mandatory embodied carbon requirements for commercial buildings.
However, embodied carbon is increasingly appearing as a project requirement through other channels. In NSW, the Sustainable Buildings SEPP 2022 requires embodied emissions disclosure for certain non-residential developments. Green Star and NABERS Embodied Carbon assessments are also being required on larger commercial projects, particularly where institutional investors or government agencies are involved.
While embodied carbon remains outside Section J, it is clearly an emerging area of building regulation. ABCB guidance has indicated that broader sustainability measures, including embodied carbon, may be considered in future NCC revisions.
NCC 2022 still governs until 1 May 2027. For projects already in design, there is no obligation to meet NCC 2025 requirements ahead of that date. But for larger projects with longer lead times, early awareness avoids costly changes closer to lodgement.
NCC version is determined by CC lodgement date, not design date or construction start. Always confirm the applicable version in writing from the certifier before commencing a Section J assessment.
We prepare Section J DTS and J1V3 reports for Class 5 to 9 commercial buildings in NSW. Fixed-fee, fast turnaround. Contact us to discuss your project.
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