NCC 2025: What Changes for Building Services

What You Need to Know

The ABCB released the NCC 2025 preview on 1 February 2026. Jurisdictions can adopt it from 1 May 2026. NSW has deferred adoption to 1 May 2027, giving the industry an extra 12 months to prepare. The changes hit every building services discipline: mechanical, electrical, hydraulic, and fire protection.

The biggest shift is energy. NCC 2025 targets near-zero operational greenhouse gas emissions for commercial buildings (Class 3, Class 5 to 9). Section J energy caps drop by up to 50% compared to NCC 2025. Mandatory on-site solar PV, tighter fan power limits, carpark sprinkler requirements, and hybrid exit signs all affect how we design and cost building services.

• Mandatory solar PV (J9D5) requires new commercial buildings to cover 100% of available roof space with PV, or meet a minimum output per square metre of conditioned floor area, whichever is smaller. Excludes trafficable zones and plant spaces. Buildings using gas must install additional PV to offset emissions (Table J9D5b).
• Greenhouse gas emissions cap introduces a new limit expressed as g CO2-e/m²/hr alongside the existing energy consumption cap. NCC 2025 Section J Performance Requirements. Applies to Class 3 and Class 5 to 9 buildings.
• Fan power ratio cap of 0.84 applies to all fans above 125 W. Compliance can be met per individual fan or on a fleet average across the building. NCC 2025 Section J DTS provisions. Single formula replaces the previous tiered approach.
• Carpark sprinkler protection now extends to open-deck carparks (except stand-alone open-deck carparks). Concessions to fire resistance levels (FRL) are reduced. NCC 2025 Volume One, fire safety amendments. Driven by increased fuel loads in modern vehicles and EV battery risks.
• Hybrid photoluminescent exit signs are now accommodated through the DTS pathway. Signs combine electric illumination with photoluminescent material for visibility during power outages. NCC 2025 Volume One, exit sign provisions.
• Battery infrastructure readiness requires main switchboards to include at least 2 empty three-phase circuit breaker slots and 4 DIN rail spaces for future battery storage. NCC 2025 J9D5 provisions. Applies unless a battery system is installed at construction.
• Plastic pipe banned above-ground in combined sprinkler and hydrant systems. Amendments clarify that AS 2118.6 referenced systems must use metal pipe above ground level. NCC 2025 Volume Three, plumbing amendments.

The mandatory solar PV requirement changes roof planning for every commercial project. Mechanical plant, cooling towers, and exhaust risers compete with PV panels for roof space. Engineers need to coordinate plant layouts earlier in design to maximise PV coverage. Buildings that use gas for heating or hot water face a penalty: additional PV capacity must offset those gas emissions, which pushes more projects toward all-electric solutions.

The 50% reduction in energy caps means HVAC systems must work harder on efficiency. The fan power ratio cap of 0.84 forces careful duct sizing and fan selection. Oversized ductwork reduces pressure drop but costs more. Undersized ductwork saves space but blows the fan power budget. The fleet-average option gives designers flexibility to exceed 0.84 on one system if another comes in well below.

Fire protection scope grows under NCC 2025. Open-deck carparks that previously avoided sprinklers now need them. This adds hydraulic load, pump sizing, tank storage, and pipe runs that were not in previous budgets. The change reflects real fire risk: modern vehicles carry more plastic, larger batteries, and denser parking layouts than when the original concessions were written.

For NSW projects, the May 2027 adoption date creates a transition window. Projects lodged before that date can use NCC 2025. Projects lodged after must comply with NCC 2025. Developers with long approval timelines should confirm which code edition applies at the point of building approval, not at DA lodgement.