Push for cooler rooftops to put ceiling on rising temperatures – The Sydney Morning Herald
“Rather than developers piloting different projects in different regions, we need to consider the need for lighter roofs nationally.
“The building ministers from the different governments have met and agree that the NCC needs to be updated to establish more resilience for the future. So, especially with the latest Intergovernmental Panel on Climate Change ‘code red’ report showing how Australia has already warmed 1.4C – in contrast to the 1.1C in the rest of the world – we’re advocating to our partners in government to do this.”
A number of studies have found that lighter roofs could make a huge difference both to city temperatures and to residents’ comfort and energy efficiency in areas that suffer summer extremes. The exceptions include chilly Tasmania, for example, where dark-coloured roofing may be more energy-efficient to keep in heat.
But for most areas, light colours would work well. Research from the University of NSW commissioned by the federal government found that Sydney’s ambient temperatures could be cut by as much as 2.4C if dark roofing was replaced by light. Inside the home, heatwave temperatures could be reduced by up to 10 degrees by the inside of the roof’s surface not radiating the heat into the roof cavity and pushing it into the interiors via the ceilings.
At the same time, the Australian government’s YourHome sustainability guide says that light-coloured roofs can reflect about 70 per cent of summer heat gain; 50 per cent more than a dark one.
‘Light tiles could produce energy savings of between 25 and 26 per cent, as against dark.’
In terms of financial savings, another study by the University of Newcastle for the Roofing Tile Association of Australia showed that light tiles could produce energy savings of between 25 and 26 per cent, as against dark, with a project by The Asia-Pacific Economic Co-operation estimating that cool roofs could save Australia as a whole, annually, US$2.29 billion.
But one of the main barriers to installing light-coloured roofs tends to be local council planners, who often recommend dark roofs to meld into the environment or not to stand out in heritage areas.
Many of the new colours available for roofing, or of roof paints, however, are subtle enough not to be conspicuous, say the manufacturers. At BlueScope Australia, spokesperson Michael Reay reports that lighter colours are becoming increasingly popular for their Colorbond roofing.
“We have a suite of 20-odd colours in our standard range and at least a third of those are in lighter colours,” he said. “We have Surf Mist, which is the most popular colour, a blue-light-grey-off-white, as well as others like Paperbark Grey, Evening Haze with a light blue-green tinge, Classic Cream and Shale Grey.
“We also have built-in Thermatech coating that reduces heat absorption and reflects light off the roof and keeps it cooler. It’s all about trying to mitigate the heat island effect.”
Ms Rooney, who’s just renovated her own house and chosen Surf Mist roofing, said cool roofs were now about the combination of colour and reflectants. “All of them are better than matt black, which is what we’ve seen for a number of years,” she said.
“We now have the opportunity to look at a palette of light colours and how they come together.”
Mr McLeod would like to see more research done on different colours too, as part of the whole range of measures to slow the rise in global temperatures.
“It would be very interesting to see how energy-efficient a blue roof, for example, could be,” he said.6 “But I wouldn’t think too many people would be adventurous enough to try that colour out …”