The National Construction Code – Are Spandrel Panels a wall or a glazing element?
Historically, when assessing the performance of a curtain wall panel, the total average U–value of the façade is calculated. If this meets the requirements of the Section J glazing calculator, it is deemed to comply with the National Construction Code (NCC).
However, this assumption is actually incorrect and not how the ABCB (Australian Building Codes Board) perceived it would be interpreted. A spandrel panel is defined as an external wall element due to the insulation component behind the glazing. As such, the centre pane R-value, must comply with the requirements for a wall.
The ABCB has developed a suite of glazing calculators to assist NCC users with the calculations required by the elemental Deemed-to-Satisfy energy efficiency provisions in NCC Volumes One and Two. This means that the glazing calculator only applies to the vision glass and as such the vision panel must meet the total U-value requirements as stipulated by the glazing calculator for each project.
This means for up and coming projects, designers will need to re-think the requirements for curtain wall specifications. For contractors, the façade needs to meet the relevant specification and it must be checked for NCC compliance given the more stringent requirements in the NCC 2011 and 2012 additions.