23 March 2020

The 2019 NCC came into effect on the 1 May 2019 with the exception of Section J. Section J had a one year phase in period due to the substantial increase in stringency.
NCC 2019 Section J Impact Report
All projects with construction certificate submitted to council after the 30 April 2020 will be required to comply with Section J 2019 code requirements.

Efficient Living has been proactively modelling the impacts of the NCC2019 changes.  We have put together a summary of the predicted impacts:

  • Conditioned class two common areas now assessed under Section J.
  • NABERs and Greenstar verification pathway:
    • Class 5, commercial, building, Section J not required if 5.5 star NABERS Commitment agreement is obtained
    • Class 3, 5, 6, 7, 8, 9 or a common area of a Class 2 building the building complies with the simulation requirements and is registered for a Greenstar Design & As Built Rating
  • Cooling has been prioritised with a focus on increased shading, lower SHGCs, more shading and lower U values in windows.
  • Increased time required to complete Section J assessment due to more complex wall glazing calculations, thermal bridging calculations and increased design advice in order to achieve compliance.

NCC Section

J1-J2 Building Fabric/Building Envelope


  • Higher performance glazing system.
  • Offer glazing performance offset opportunities without JV3 pathway by increasing wall performance.
  • Increased requirement for shading. Allowable SHGC values to reduce and as such glazing with high Visible Light Transmittance (VLT) to be considered to allow for clearer glass – more expensive system.
  • Holistic façade calculator which allows orientations with low glazing ratio to benefit façade with greater ratio, this will impact U-value only, SHGC assessed by individual façade.
  • Display glazing for a retail shop now always allowed at U-Value 5.8 and SHGC 0.81.
  • Medium and light roof construction only, maximum solar absorptance of 0.45 for DTS assessment.
  • Thermal bridging calculations now required, typical assumption of 15% bridging area in walls, resulting in increased wall insulation requirements by approximately 20% or greater.
  • Metal framing to walls and windows will now have a lager negative impact on results. Continuous insulation options perform best.
  • Thermal breaks to be considered for all construction types to reduce effect of thermal bridging.
  • Fire engineers should be contacted prior to installing insulation. A performance solution may be required.
  • Only certain types of spandrel will now be compliant. If no product performance values are provided, default values from Section J will be used requiring a minimum of a double glazed spandrel with a thermally broken frame with R1.0 insulation as a minimum to comply.
  • Slab on ground floors with a high floor perimeter to floor area ratio will now require insulation to achieve a total system R value of R2.0.
  • Floors with in slab heating/cooling require an R 3.25 insulation.

J5 Air Conditioning & Ventilation Systems

  • Under NCC 2019 recirculating range hoods are not compliant and therefore require ducting to the façade.
  • Increased requirements for outdoor air heat recovery and CO2 control.
  • Increased fan system efficiency requirements.
  • Increased pumping system requirements.
  • Increased piping insulation requirements.
  • Maximum pressure drops permitted in airside and waterside systems decreased.
Efficient Living Commercial Services

Efficient Living has one of the largest teams of Sustainability Consultants and provide a range of commercial consulting services including Section J, JV3, NABERS, DA Reports & Onsite Compliance.

With over 20 years experience and leading industry expertise, we deliver better outcomes for our clients with more efficient and cost effective solutions.