Every commercial building in NSW has to show it meets the energy efficiency requirements in Section J of the National Construction Code. There are two practical ways to do that. The choice can make a real difference to both the consultant fee and the construction cost.
How NCC compliance works
The NCC sets performance requirements. You can meet them with a Deemed-to-Satisfy (DTS) solution, which follows the prescriptive provisions, or a Performance Solution, which shows the requirement is met some other way. Section J provides verification methods for Performance Solutions, and J1V3 is the one most often used for energy efficiency.
The DTS report
A DTS report checks each part of the building against the tables and clauses in Parts J4 to J9:
- Fabric: roof, ceiling, wall and floor R-values, and total system U-value and solar heat gain for walls and glazing
- Sealing: doors, windows, exhaust fans and roof lights
- Air-conditioning: plant efficiency, controls, fans, ducts and pipework
- Lighting: lighting power allowance for each space type, plus controls
- Hot water and pools
- Energy monitoring and provision for on-site energy resources
Every element has to pass on its own terms. If the glazing doesn’t meet the table, the glazing has to change, whatever else the building does well.
Best for: tenancy fitouts, small to medium new buildings, warehouses and industrial buildings with limited glazing, and any project where the design already complies comfortably.
J1V3 modelling
J1V3 compares two computer models of the building over a full year of weather:
- The proposed building, as designed.
- A reference building with the same geometry and use, built to the DTS minimums.
If the proposed building’s annual energy use (greenhouse gas emissions under NCC 2022) is no more than the reference building’s, and it meets the other J1V3 conditions, it complies. The building doesn’t have to pass element by element. Better lighting, more efficient air-conditioning or better shading can make up for glazing that wouldn’t meet the DTS tables.
Best for: glass-heavy offices and retail, buildings with feature facades, schools and community buildings with large glazed areas, and projects where DTS upgrades would be expensive or would compromise the design.
Side by side
| DTS report | J1V3 modelling | |
|---|---|---|
| Consultant cost | Lower, from $950 | Higher, quoted per project |
| Time | Days | One to three weeks |
| Design flexibility | Low, every element must pass | High, trade-offs allowed |
| Construction cost | Can be higher if upgrades are forced | Often lower on glazed buildings |
| Inputs needed | Drawings and specifications | Drawings, services design and operating profiles |
A quick way to decide
- Fitout with no facade changes? DTS. The report will focus on lighting and air-conditioning.
- Glazing well under half of the facade and ordinary construction? DTS will usually pass.
- Big glazed facade, or DTS says you need premium glass everywhere? Price J1V3. The glass saving can cover the modelling fee many times over.
- Not sure? Start with a DTS check. It shows where the design fails, and whether J1V3 is worth it.
Under NCC 2025 the DTS provisions get tougher, including solar PV and tighter fabric and HVAC requirements. Expect more projects to find that J1V3 is the cheaper route. What changes in NCC 2025 →
What the certifier needs
Either way, the certifier needs a report showing how each Section J requirement is met, and drawings and specifications that match it. A good report tells the design team exactly what to put on the drawings: insulation, glazing specifications, lighting limits and control requirements. That avoids a round of requests for information at CC stage.
Not sure which Section J pathway fits?
Assessments prepared from your drawings, anywhere in NSW. Turnaround is confirmed in your quote and starts once all required information is received.
General information only, current at the date above. Requirements change and every project is different, so confirm the rules that apply to your project with your certifier or council.