Here’s our take on it. Please do your own research and verify latest facts before using any information. The NCC 2019/22 updates emphasize energy efficiency, specifically focusing on reducing thermal bridging in building envelopes to improve insulation performance and overall energy efficiency. Here’s a deeper look at how these changes impact roofing design:
1. Thermal Bridging in Roofing
Thermal bridging is a significant concern in metal roofing systems because metal is a high conductor of heat. When conjoined metal components like purlins and insulation spacers create a continuous thermal path between the outside and inside, they can lead to substantial heat transfer. This can cause unwanted heat loss in winter or heat gain in summer, decreasing the building’s energy efficiency and driving up heating and cooling costs.
2. Thermal Breaks in Insulation Spacers
To address these issues, NCC 2019/22 encourages designers to integrate thermal breaks within spacer brackets. A thermal break is typically a material with low thermal conductivity that interrupts the thermal pathway through the spacer, thereby reducing the transfer of heat through metal components. Materials used for thermal breaks might include plastic or rubber components or components that are specifically made for this purpose.
3. Compensating with Increased Insulation
When a complete thermal break isn’t feasible or in conjunction with thermal breaks, designers can opt to increase the thickness or quality of the insulation surrounding the thermal bridge area. This involves using insulation materials with higher R-values (a measure of thermal resistance) around and over spacers. Thicker insulation layers reduce the thermal impact of any remaining bridging effect, creating a buffer to keep internal spaces thermally stable.
4. Energy Rating Requirements and Compliance
Under the updated NCC, buildings must meet specific energy performance standards, and part of this involves controlling heat transmission via thermal bridges. Roof systems must be assessed to ensure they meet these standards, taking into account the total roof area, insulation material types, and how thermal bridging influences the overall performance. Compliance may involve modeling heat flow through the roof system to verify that the building meets the desired energy rating, especially for commercial and industrial structures with larger roofing spans.
5. Designing for Specific Climate Zones
The NCC’s focus on thermal bridging and energy efficiency also varies by climate zone. In hotter areas, thermal bridging can lead to excessive cooling loads, while in colder areas, it can increase heating demands. Designers and engineers are expected to tailor roofing systems accordingly, potentially opting for more advanced insulation strategies or spacer designs in extreme climates to meet energy efficiency targets.
By addressing these aspects, the NCC 2019/22 changes drive advancements in both roofing materials and design strategies, promoting sustainable, cost-effective construction aligned with Australia’s energy efficiency goals.
Decke is proactively addressing future NCC requirements by introducing a thermal break in its insulation spacers. This break will consist of a 3mm layer of specially manufactured rubber material applied to the base of the spacer leg, creating a thermal gap between the purlin and the spacer. This gap disrupts direct thermal conductivity, effectively reducing heat transfer and enhancing the insulation’s effectiveness. By incorporating this solution from January 2025, Decke is preparing to meet anticipated guidelines on thermal bridging and energy efficiency.
Read more about Decke’s insulation spacers on https://deckeglobal.com.au/insulation-spacers/