Cool roofing: A smarter choice for energy efficiency and urban heat reduction
With Australia’s extreme heat, keeping homes comfortable without excessive energy use is a growing priority for homeowners.
Cool roofs, those designed and constructed from materials that reflect more solar energy and emit heat more efficiently, help limit the amount of heat entering a building. By combining high solar reflectance and high thermal emittance, these roofs reduce the amount of solar energy absorbed and quickly release more captured heat back into the atmosphere. The result can be a cooler interior, lower energy costs, and a more comfortable space – all while contributing to a reduction in the building’s environmental impact and enhancing energy efficiency.
How cool roofs benefit Australian homes
Under the National Construction Code (NCC) Energy Efficiency provisions (and BASIX in NSW), a roof’s solar absorptance (SA) is taken into account when applying the NatHERS star rating system and may influence insulation requirements.
For homes exposed to South Australia’s hot summers, choosing a low-solar absorbance roof can assist in keeping indoor spaces cooler while reducing long-term cooling costs. Lighter-coloured roofing materials are particularly effective at reflecting the sun’s energy and lowering heat absorption.
Cool roofs may provide several advantages, including1:
- Improved thermal comfort – Less heat absorption helps keep indoor temperatures lower.
- Reduced energy consumption and emissions – Lower reliance on air conditioning cuts electricity use and greenhouse gas emissions.
- Lower maintenance costs – Minimising heat stress may help extend the lifespan of roofing materials and air conditioning units.
- Optimised solar panel performance – Cooler roof surfaces improve solar panel efficiency by reducing heat stress on the panels themselves.
- Urban Heat Island (UHI) mitigation – When widely adopted, cool roofs can help lower temperatures across communities and suburbs.
The research behind cool roofs
A study by the High Performance Architecture research group at UNSW found that cool roofs benefit even single dwellings. Thermal imaging comparing dark and white coloured residential roofs on a 37°C day in Western Sydney showed a significant temperature difference, with cool roofs reducing peak indoor air temperatures during heatwaves.
Beyond individual homes, the study found that cool roofing has a broader regional impact.
The Urban Heat Island (UHI) effect refers to how built-up areas absorb and retain heat, leading to higher temperatures in cities and suburbs compared to surrounding rural areas.
By reducing heat buildup across multiple properties, cool roofs may help lower local temperatures, improving comfort not just inside homes, but in entire communities. The research found that in Adelaide, along with other mainland state capitals, the energy savings from cooling far outweigh any minor heating penalties.
COLORBOND® steel: A smart roofing choice for Australian homes
Balancing aesthetics and performance, COLORBOND® steel offers a range of light-coloured options for roofing that help homeowners and builders achieve better thermal efficiency without compromising on design. These light, naturally inspired tones also complement both modern and heritage-style homes.
Additionally, 21 of COLORBOND® steel’s Classic colours (all except Night Sky®) and all six COLORBOND® steel Matt colours feature Thermatech® solar reflectance technology. Thermatech® reflects more energy from the invisible near-infrared spectrum, reducing heat absorption without changing the roof’s colour.
While paler colours and Thermatech® technology enhance energy efficiency in individual dwellings, they also play a role in mitigating the UHI effect. By reflecting more of the sun’s energy and absorbing less heat, COLORBOND® steel may help reduce overall cooling demand, supporting more energy-efficient communities.
- Results will depend on a wide range of factors including roof colour, roof shape, level and location of insulation, type, location, shape, and function of the building.
Further information
- Visit COLORBOND® steel Cool Roofing on STEEL SELECT® to explore a range of resources, view articles, see the core range of COLORBOND® steel cool roofing colours, and download brochures.