A cool roof this summer

Issue 29 Words: Blaire Dobiecki Photography: G Smith via YourHome.gov.au

The colour, shape and structure of our roofs all impact on internal house temperatures. As our summers are tipped to become longer and hotter, how can our roofs best
meet this challenge and keep us cool?

If you studied the average Australian roof you would be forgiven for thinking we inhabit a relatively cool continent. From poorly installed low-grade insulation to black heat-absorbing tiles, there are plenty of design elements we could reconsider to help keep our homes cool in summer.

Insulation

In terms of prioritising these design elements, “insulation will always come first,” says senior lecturer in architecture Dr Dominique Hes of Melbourne University. She recommends using renewable or recycled materials, although the type of material you use is not as important as the thermal resistance (or R-value) of that material. The higher the R-value, the more the material inhibits the transfer of heat and the better it works as an insulator. “If you look at the embodied energy analysis, putting in a good amount of insulation will always save you more energy than the embodied energy in the insulation, whether it’s plastic, glass or whatever,” says Dominique.

Ventilation

If you have attic space, ventilation is the second priority for most areas of Australia. Venting hot air from a high position in the roof minimises the heat energy transmitted through the ceiling into living spaces. Typical vents include roof plane ‘whirlybirds’, roof ridge vents, gable vents and eave soffit vents (which let air into the underside of the eave). Roof venting gives a high reduction in heat transmission for a relatively low cost.

Colour

Painting your roof white with a high albedo rating (measure of reflectivity) paint is an easy way of lowering inside temperatures without rebuilding the structure. Indeed, Dominique suggests that “white roofs are a good thing for any part of Australia”. A cool roof could make internal daytime winter temperatures cooler by reducing heat absorption, but with a well-insulated ceiling should have a much smaller impact. “If in doubt, go white,” Dominique recommends.

Read about cool roof paints, condensation, roof materials and green roofs in the full article. 

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Cover of Issue 29
You can read more about A cool roof this summer in Issue 29 of Sanctuary magazine.

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Sanctuary: modern green homes is Australia’s premier magazine dedicated to sustainable home design. More...

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Did You Know?

Up to 60 per cent of the water used in an average home is used outside.

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