Section J of the National Construction Code (NCC) Volume One codifies minimum glazing thermal performance measures for both facade vision glazing and roof lights.
NCC 2019 contained the first major revision to the Section J measures in nine years. A significant change was the amalgamation of the external wall insulation requirements with facade glazing requirements into a new Part J1.5 in NCC 2019. This is now called Part J4D6 ‘Walls and glazing’ in NCC 2022. This requirement in the code accounts for the significant detrimental effects of thermal bridging through metal framing within wall construction.
The continuing difficulty with Section J is that it fails to explain succinctly to a designer what a compliant design might look like. This paper attempts to address this failure by presenting a range of strategies and design charts for different climate zones to enable building designers to quickly design high-performance, NCC-compliant facade concepts.
This note updates and replaces Environment Issue 04 October 2019 (edited April 2020) NCC 2019 Section J and Commercial Building Facade Design to reflect the minor commercial energy efficiency changes introduced into NCC 2022. Transition arrangements apply in some states and territories where NCC 2019 Section J clauses can still be used beyond the NCC 2022 adoption date of 1 May 2023. Refer to your jurisdiction’s building authority for the relevant state and territory adoption dates.