What is Section J of the NCC?

Section J is the energy efficiency section of the National Construction Code (NCC) 2022, Volume One. It sets minimum performance standards for building fabric, glazing, HVAC systems, lighting, hot water, and building sealing in Class 2 to 9 buildings. Every commercial and multi-residential building in Australia needs a Section J assessment to get a Construction Certificate or Complying Development Certificate.

When do you need a Section J report?

You need a Section J report for any new Class 2 to 9 building, or any major alteration to an existing Class 2 to 9 building. This includes apartments (Class 2), hotels (Class 3), offices (Class 5), shops (Class 6), warehouses (Class 7), factories (Class 8), and public buildings like schools and hospitals (Class 9). The report must be submitted with your Construction Certificate or Complying Development Certificate application.

How much does a Section J report cost in Australia?

A DTS Section J report costs $2,000 to $5,000 for most commercial projects. A JV3 performance modelling report costs $5,000 to $15,000 or more, depending on building size and complexity. Simple single-storey buildings sit at the low end. Large multi-storey or mixed-use buildings sit at the high end.

Who prepares a Section J report?

An accredited energy assessor or a building services engineer with energy efficiency expertise prepares the report. For DTS assessments, the assessor checks each building element against the prescriptive requirements. For JV3, the assessor uses thermal simulation software to model the building's energy performance. The report is submitted to the certifier as part of the Construction Certificate application.

Section J Compliance: What Builders and Developers Need to Know

Q: What is the difference between DTS and JV3 for Section J?

DTS (Deemed-to-Satisfy) is the prescriptive pathway. Each building element must meet a fixed minimum standard. It is faster and cheaper. JV3 (now called J1V3 under NCC 2025) is the performance pathway. An energy assessor builds a computer model of the building and proves total energy use stays below a reference building. JV3 gives more design flexibility but costs more and takes longer.

Section 1

What Section J Is

Section J controls how much energy a commercial building can waste. It sits inside the National Construction Code (NCC) 2022 Volume One and applies to every Class 2 to 9 building in Australia. That covers apartments, offices, shops, warehouses, factories, schools, and hospitals. You cannot get a Construction Certificate (CC) or Complying Development Certificate (CDC) without a Section J assessment.

The rules cover six areas: building fabric insulation, glazing performance, building sealing, air-conditioning and ventilation efficiency, artificial lighting, and hot water systems. NCC 2025 tightened these standards significantly compared to NCC 2019, and added new requirements for solar-ready roofs, EV charging infrastructure, and energy monitoring.

Section 2

DTS vs JV3: Two Compliance Pathways

DTS (Deemed-to-Satisfy) is the prescriptive pathway. Each building element must meet a fixed minimum standard. Wall insulation hits a set R-value. Glazing meets a set U-value and SHGC. Lighting stays under a set power density. The assessor checks each element against the NCC tables and either it passes or it does not. DTS is faster, cheaper, and works well for straightforward designs.

JV3 (now called J1V3 under NCC 2025) is the performance pathway. An energy assessor builds a thermal simulation model of the entire building using software like IES VE or EnergyPlus. The model calculates total annual energy use and compares it to a reference building that just meets DTS. If the proposed building performs equal to or better than the reference, it passes. JV3 gives more design flexibility. You can have more glass on one wall if you offset it with better insulation elsewhere.

When to use each: Pick DTS for simple buildings with standard construction. Pick JV3 when the design has large glazing areas, unusual shapes, or high-performance goals that go beyond minimum code. NCC 2025 improved the DTS method so it now handles more project types without needing JV3.

Section 3

What Section J Covers

Building fabric insulation: Walls, roofs, and floors must meet minimum R-values based on climate zone. Higher R-values in colder and hotter zones. (NCC 2025, Part J4)
Glazing performance: Windows and curtain walls must meet maximum U-values and Solar Heat Gain Coefficient (SHGC) limits. More glass means stricter targets. (NCC 2025, Part J4)
Building sealing: The envelope must limit uncontrolled air leakage. Seal all penetrations, joints, and openings in the building shell. (NCC 2025, Part J5)
Air-conditioning and ventilation: HVAC equipment must meet minimum efficiency ratings. Ductwork needs insulation and sealing. Controls must allow zoning and scheduling. (NCC 2025, Part J6)
Artificial lighting: Maximum lighting power density applies to each space type (measured in W/m²). Automatic controls such as occupancy sensors and daylight dimming are required in most spaces. (NCC 2025, Part J7)
Hot water systems: Water heaters must meet minimum efficiency standards. Pipe insulation and circulation pump controls reduce standby losses. (NCC 2025, Part J8)
Solar-ready roofs: Buildings with roof area over 55 m² must keep at least 20% of roof area clear for future solar panels. (NCC 2025, Part J9)
EV charging readiness: Car parks with 10 or more spaces per storey must have dedicated electrical distribution boards for future EV chargers. (NCC 2025, Part J9)

Section 4

How Much a Section J Report Costs

The cost depends on the building size, complexity, and which compliance pathway you choose.

DTS Assessment

A DTS report costs $2,000 to $5,000 for most commercial projects. Simple single-storey buildings (warehouses, small retail) sit at the low end. Multi-storey offices and mixed-use buildings sit at the high end. Turnaround is typically 1 to 2 weeks once design drawings are available.

JV3 Performance Modelling

A JV3 report costs $5,000 to $15,000+. The assessor builds a full thermal model, which takes more time. Large hospitals, laboratories, and multi-building campuses can push costs higher. Turnaround is 3 to 6 weeks depending on model complexity and design iterations.

Who Prepares It

An accredited energy assessor or a building services engineer with energy modelling capability prepares the report. The report goes to the building certifier as part of the CC or CDC application. Choose an assessor early in design, not after construction drawings are finished. Late involvement often means costly redesign.

Section 5

Key Design Decisions

1

DTS or JV3: Choose the Right Pathway Early

Start with DTS. If the design has glazing ratios above 40% of wall area, complex shading, or atypical geometry, switch to JV3. Ask the energy assessor at concept stage, not after DDs are done.

Trade-off: DTS saves $3,000 to $10,000 in assessment fees and 2 to 4 weeks. JV3 gives design freedom but adds cost and requires more coordination between architect and engineer.

2

Glazing vs. Insulation Balance

More glass means more solar heat gain and higher cooling loads. If the architect wants floor-to-ceiling glazing, the HVAC system works harder and the Section J assessment gets tighter. Under DTS, there are hard limits on glazing area by orientation. Under JV3, you can offset large glazing with better insulation, shading, or more efficient HVAC.

Trade-off: Reducing glazing by 10% on the west face of a building can cut cooling plant size by 15 to 20%, saving capital cost. But it changes the architectural design. Resolve this at concept stage.

3

HVAC Efficiency: Meet Code or Exceed It

Part J6 sets minimum equipment efficiency. Specifying equipment above minimum (e.g. a VRF system with COP of 4.5 instead of the code minimum) creates headroom for other elements that may fall short. Under JV3, a high-efficiency HVAC system can offset weaker building fabric performance.

Trade-off: Higher-efficiency HVAC costs 10 to 20% more upfront but reduces operating costs and makes the Section J assessment easier to pass. It also creates buffer if the design changes during construction.

4

Engage the Energy Assessor at Concept Stage

The most common problem with Section J: the assessor gets involved too late. By the time construction drawings are done, the building fabric and glazing are locked in. If the design fails Section J at that point, you are looking at redesign, re-documentation, and program delays.

Trade-off: Early engagement adds a small fee (typically $1,000 to $2,000 for a preliminary review) but avoids $10,000+ in redesign costs and 4 to 8 weeks of delay later.

Section 6

Who Needs to Know What

Section 7

References

National Construction Code 2022, Volume One, Section J: Energy Efficiency (Parts J1 to J9)
Australian Building Codes Board (ABCB), Energy Efficiency Handbook, NCC 2025
NCC 2025, Part J4, Building Fabric (insulation R-values, glazing U-values and SHGC)
NCC 2025, Part J5, Building Sealing
NCC 2025, Part J6, Air-conditioning and Ventilation
NCC 2025, Part J7, Artificial Lighting and Power
NCC 2025, Part J8, Heated Water Supply and Swimming Pool and Spa Pool Plant
NCC 2025, Part J9, Energy Monitoring and On-site Distributed Energy Resources
AS 1668.2:2012, The use of ventilation and airconditioning in buildings, Part 2: Ventilation design for indoor air contaminant control