Colour selection and what is prescribed under the NCC?

Colour selection and what is prescribed under the NCC?

Our buildings’ colour palette today is very different to that of 50 years ago. From traditional brick walls and dark roofs, an improved understanding of how these colours impact on building thermal performance and efficiency has resulted in an evolution in building design that takes into account climate zones and building use, and utilises colour to reflect or absorb heat while still enabling creative expression. This evolution has been supported by Bluescope with a wide range of high performance, full colour range steels and is now standardised in building practices under the NCC 2019. Dark coloured roofs will no longer be permitted under the Deemed to Satisfy (DtS) provisions. Commercial buildings will need a light-coloured roof, with all climate zones (except for Climate Zone 8) requiring a maximum solar absorptance of 0.45 to comply. This means that any commercial roof assessed under the DtS provisions will need to be Surfmist®, Classic Cream™, Paperbark®, Shale Grey™ or Evening Haze®. All medium or dark coloured roofs, including “green” roofs, dark concrete and membrane roofs require a performance-based solution using JV3 to demonstrate compliance.

Deemed to Satisfy Performance Solution
 MetecnoPIR Insulated Panels: acceptable external skin colours based on BlueScope’s guidelines on max skin temperature
  Exposure Category
1 2 3 4
PIR core
(< 100oC)
Classic Cream™ Classic Cream™ Classic Cream™ Classic Cream™
Surfmist® Surfmist® Surfmist® Surfmist®
Paperbark® Paperbark® Paperbark® Paperbark®
Shale Grey™ Shale Grey™ Shale Grey™ Shale Grey™
Dune® Dune® Dune® Dune®
Pale Eucalypt® Pale Eucalypt® Pale Eucalypt® Pale Eucalypt®
Manor Red® Manor Red® Manor Red® Manor Red®
Basalt® Basalt® Basalt® Basalt®
Woodland Grey® Woodland Grey® Woodland Grey® Woodland Grey®

^ Note: limited warranty – contact MetecnoPIR for further details

So, what is Solar Absorptance?

Solar Absorptance (SA) is the fraction of the total incident solar radiation that is absorbed by the roofing material, with the remainder being reflected. SA is expressed as a ratio between 0 and 1. A roof with a lower SA will absorb less heat, compared to a roof with a higher SA, which will help in keeping the roof space and the building cooler.

For detailed information on NCC 2019 Volumes One and Two please refer to the ABCB website. Volume One of NCC 2019 primarily regulates multi-residential, commercial, industrial and public assembly buildings and some associated structures. NCC Volume One requires the Solar Absorptance of the upper surface of the roof to be less than or equal to 0.45 for the DtS pathway. Roof surfaces with SA greater than 0.45 must use the Performance Solution pathway to compliance.

What does this mean for insulated panel colours?

MetecnoPIR are guided by the NCC and the BlueScope’s recommendations for appropriate colours, with the addition of special requirements specific to insulated panel. MetecnoPIR roof panels acceptable external colours based on COLORBOND®’s guidelines of maximum skin temperature can be seen below

PROPOSED Bondor/Metecno Panel’s’ acceptable external skin Solar absorptance values based on BlueScope’s guidelines on max skin temperatures
Application Roof – max solar absorptance value
Panel Type Exposure Category
1 2 3 4
MetecnoPIR Roofing
(< 100oC)
0.75 0.96 0.96 0.96

Exposure Category Regions

Exposure category 1 – Extreme inland Exposure category 3 – Cooler regions of mainland Australia
Wilcannia, Oodnadatta, Swan Hill, Mardie Toowoomba, Mackay, Cooma, Port Stephens, Omeo, Gladstone, Bowral, Lithgow, Bright
Exposure category 2 – Majority of seaboard Australia Exposure category 4 – Tasmania
Melbourne, Sydney, Brisbane, Townsville, Adelaide, Perth, Cairns Hobart, Launceston, Devonport