Raising your roof consciousness may help rein in global warming, writes Sarah Pickette.

Look out over just about any city or town in Australia and you'll take in a sea of red or dark roofs. It's a familiar aesthetic, but could it actually be a hindrance to the thermal efficiency of our homes? Most of us accept the idea that dark surfaces absorb more heat than lighter ones, so it stands to reason that choosing a lighter-coloured roof can have an impact on the temperature inside your house. Of course, nothing is ever quite that simple. Other factors, such as the level of insulation and the design of the house, also come into play. Then there are the issues of conformity and the glare that a light-coloured roof may inflict on neighbouring homes.

Still, the idea of using a lighter-coloured roof, which will reflect more of the sun's heat, has plenty of support from environmentally aware architects and homeowners looking to maximise the energy efficiency of their home.

"I advise clients to choose a light to medium colour for their roof, like a light to mid-grey," says Glen Spicer, Director of EJE Architecture in Newcastle, NSW. "A mid-grey roof colour still reflects a lot of heat but causes less glare than a very light colour."

Changes to the Building Code of Australia have made it mandatory for new residences to achieve at least a six-star energy rating. This will require builders and homeowners to rethink roofing materials and their role in keeping energy consumption in check, says Brian Kelly, National Marketing Manager of BlueScope Steel, which produces Colorbond steel roofing. "Seven colours in the Colorbond steel palette are now classified as ‘light' or ‘very light' under BASIX [Building Sustainability Index] and the Building Code of Australia's colour classification," he says. "This offers homeowners a greater choice of colours and, in some parts of Australia, could mean a reduced amount of insulation is required to meet building regulations."

How much impact roof colour can have on energy consumption is hotly debated. However, it's worth noting that Dr Steven Chu, a Nobel Prize winner and US Secretary of Energy, has declared that universally making roofs, (plus roads and pavements) white or light-coloured could reduce global warming by conserving energy and reflecting sunlight. It would, he claimed, be equivalent to taking every car in the world off the road for 11 years.