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BCA Section J-DTS & JV3 modelling

To comply with Section J of the NCC 2019, one of the following compliance paths can be pursued:

  • Compliance with deemed-to-satisfy (DTS) provisions; or
  • Compliance with an Alternative Solution

Compliance with DTS provisions is achieved when the building design meets minimum section J requirements outlined in BCA.

Performance Requirements JP1 are satisfied by complying with

  • (a) for reducing the heating or cooling loads
  • Compliance with deemed-to-satisfy (DTS) provisions; or
  • Compliance with an Alternative Solution
  • (b) for air-conditioning and ventilation, Part J5; and
  • (c) for artificial lighting and power, Part J6; and
  • (d) for heated water supply and swimming pool and spa pool plant, Part J7; and
  • (e) for facilities for monitoring, Part J8.

Difference with the previous versions

What are the changes

  • Residential buildings (class 1, 2 and 4) – Introduced NatHERS heating and cooling load limits (on top of existing minimum star rating) for Class 1 building. For NSW, BASIX compliance requirements remain relatively unchanged
  • Commercial buildings (class 2 common area, 3, 5, 6, 7, 8 & 9) – Increased compliance provision requirements and added new verification methodologies, primarily included:
  • Changed energy consumption to greenhouse gas emissions – Increase weighting on renewable energy sources, i.e. Solar PV and onsite heat reclaimed systems
  • Introduced NABERS and Green Star verification pathway – Prequalification for Green Star & NABERS projects
  • Introduced Building Envelope Sealing verification pathway – Require blow test
  • Implemented occupancy comfort assessment clause – Required thermal comfort modelling to assess PMV level
NCC Section J Parts 2016 DTS compliant 2019 DTS compliant (NCC19 Preview) Potential Impacts
J1-Fabric Follow prescriptive R-value requirement for all fabric elements Non-Façade element – Follow prescriptive R-value requirement for roof, ceiling, roof light and floor Façade element – new calculation methodology to determine wall & glazing performance requirement
  • Thicker building fabric insulationo Insulation required for all floor types
  • Higher performance glazing system
  • Offer glazing performance offset opportunities without JV3 pathway.
  • Greater benefits for low glazing ratio building design OR building which has concentrated glazing on a fixed orientation but opaque element for the other facades
  • J2-Glazing (Removed) Independent from wall thermal performance requirement, follow ABCB prescribed glazing calculator to determine glazing performance requirement New manual calculation to assess wall & glazing requirements as a combined façade element.
  • Longer turnover time to determine compliance requiremento Early commitment to wall construction type
  • The same building façade requires better glazing system or reduction in glazing ratio, compared to NCC16**
  • J3-Building Sealing Prescriptive sealing requirement No fundamental change N/A
    J5-Air-conditioning & ventilation systems Prescriptive requirements to select mechanical systems based on the minimum targets Improved prescriptive requirements
  • Increased Control – VSD, temperature band, comfort, damper & time switch
  • Improved outside air treatment
  • Increased Fan efficiency
  • Added EU regulations requirement for Pump system
  • Increased insulation
  • Increased heating thermal efficiency
  • Increased chiller/unitary system efficiency
  • Improved heat rejection fan equipment power
  • Stricter requirements for system control/fan/pump/insulation/efficiencyo Possible new calculator for mechanical systems
  • J6-Artificial lighting & power Prescriptive requirements to select lighting systems based on the minimum targets
  • Added criteria for light quality – CRI & CCTo Significant reduction of max lighting power density
  • Revised control device adjustment
  • Added criteria for carpark lighting & control
  • Added criteria for lift energy, escalator & moving walkway control
  • Greater lighting control coverage
  • J7-Heated water supply and swimming pool and spa pool plant Prescriptive requirements to select heated water systems based on the minimum targets No fundamental change, increased system efficiency, insulation and control N/A
    J8-Facilities for energy monitoring Prescriptive requirements to select energy monitoring system No fundamental change, added needs for time-of-use data capturing capability N/A


    On the other hand, compliance with an alternative Solution applies when a building's design does not meet DTS provisions, or when a more economical solution is available. To show compliance with an alternative solution, the JV3 Verification method outlined in the BCA is used to model a building’s annual energy consumption against its energy consumption complied with DTS provisions. To do JV3 modelling, a reference building model that meets DTS provisions is created and its annual energy consumption is compared against the proposed model’s annual energy consumption. As outlined in the BCA, compliance with JV3 verification method is met when the proposed building’s annual energy consumption is less than or equal to the reference building’s annual energy consumption. JV3 allows more flexibility to design a development meeting energy efficiency requirement by looking at buildings’ façade and services in more details as long as its energy usage does not exceed the reference buildings energy usage targets.