NCC 2019 Section J and commercial building facade design

Synergy, CSIRO by BVN (Image: John Gollings)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 contains the first major revision to the Section J measures in nine years. A significant change is the amalgamation of the external wall insulation requirements (Part J1.5) with facade glazing requirements (previously in Part J2) into a new look Part J1.5 called wall-glazing. In doing so, the code now acknowledges the significant detrimental effects of thermal bridging through metal framing within insulated spandrel panels of curtain 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 EDG 86 MS NCC Section J and Commercial Building Facade Design to reflect the changes introduced into NCC 2019 (as mandated from 1 May 2020).

Related course:
  • Masterclass: NCC Section J – Unpacked & Demystified: 1 & 2 (Available via Online CPD)
note summary
  1. Introduction
  2. Key concepts
  3. Graphs
  4. Example of a glazing concept using the WWR graphs
  5. Summary and further recommendations
  6. Glossary of terms