NCC2025 Section J (Commercial Buildings) Update

J4D4 Building fabric – roofs and ceiling construction 

• Updates to Total R-Value requirement for a roof or ceiling 

• Includes higher reflectance and new requirement for emittance of metal roof of a building with rooftop air conditioning equipment 

J4D6 Building fabric- Wall-glazing construction 

• Requires thermal performance of wall-glazing constructions to be assessed for each story, including any mezzanine 

• Requires more stringent solar admittance requirements for wall-glazing in all building classifications and climate zones 

• Updates to wall-glazing, Maximum Total System U-Value and opaque wall Total R-Value 

J6D3 Air-conditioning system controls 

• Updates to the air-conditioning control requirements to restrict simultaneous heating and cooling and prevent poor design 

• Updates to reduce the threshold to provide economy in some climate zones 

• Updates to add temperature reset requirement for heated water and condenser water 

• Expansion of requirement for interlock to prevent air-conditioning from operating when an external door is opened 

• Updates to the time-switch provisions to improve functionality and align with provisions for time-switches used to control lighting 

J6D4 Mechanical ventilation system controls 

• Updates to require energy reclaim systems to be fitted with a bypass where beneficial 

• Reduces threshold to provide outside air treatment in some climate zones 

• Includes separate provisions for outside air treatment for variable and constant outside air flow systems 

• Includes a requirement for indirect evaporative cooling for larger, constant outside air ventilation systems in climate zone 1 and 3 

• Removes variable speed fan requirements. Refer to J6D5 for related changes 

• Updates to the time-switch provisions to improve functionality and align with the provisions for time-switches used to control lighting 

J6D5 Fans and duct systems 

• Updates to the provisions to align with EU327 

• Updates to require peak efficiency and duty point efficiency to both be considered 

• Updates to allow the efficiency at duty point to be assessed individually or collectively 

• Includes a requirement for most fans to be capable of variable speed operation where the input power is above 750W 

• Updates to require fans serving multiple rooms or spaces to be capable of variable pressure operation, to the extent practicable 

• Addition of pressure drop allowance for exhaust louvres and relief louvres 

• Refer also to changes to Specification 46 

J8D3 Heated water supply 

• Updates to clause numbering  

• Updates to facilitate future electrification, including reserved electrical infrastructure capacity, plant space 

• Includes insulation requirements for pipework containing circulating heated water used for sanitary purposes and food preparation 

J9D4 Facilities for EV charging equipment 

• Updates to allow bus ducts to be used with EV charging equipment 

• Includes a requirement to specify the maximum permitted length of the cable run from EV charging distribution board or bus duct to car parking spaces 

• Includes requirements for EV chargers for a specified number of spaces in carparking areas associated with a Class 3, 5, 6, 7b, 8 and 9 buildings 

• Updates to the infrastructure requirements for future EV charging in recognition that these provisions are additional to the requirement to install EV charging equipment 

J9D5 Renewable energy 

• Updates require on-site PV panels to be installed. Capacity depends on the available roof space, climate zone and building classification. Additional PV is specified where gas is used to balance the emissions from gas appliances 

Plus, numerous other amendments.  

For the full list refer to: PCD 2025 – Commercial building energy efficiency | ABCB