Reflective roof coatings offered as low-cost way to reduce heat indoors

Reflective roof coatings are being promoted as a relatively low-cost way to reduce heat entering Australian homes as the country prepares for a potentially hot summer. Nic Jacobsen, an Adelaide homeowner and renewable-energy engineer, said upstairs rooms in his house remained uncomfortably hot even after he improved insulation. He then applied a heat-reflective coating to the roof and western wall and said the reduction in heat was immediate.

He believed the change had significantly reduced his air-conditioning bill, although he did not quantify the saving. Most Australian roofs are metal or tiled, and many are medium or dark in colour. Lighter surfaces generally reflect more heat.

Shane Strudwick, who distributes one ceramic coating, said a basic Adelaide trial found untreated concrete tiles reached 60C on a 22C day, while coated tiles reached 26C. The source says a University of New South Wales cost-benefit analysis found that coating a functional roof could be recovered through energy savings and by extending the roof’s life. Western Sydney University researcher Sebastian Pfautsch said coating a dark roof could be a useful first step before installing solar panels or improving insulation.

University of Sydney professor Chiara Neto said applying roof paint was among the most efficient low-cost retrofits and could save up to 40 per cent of an energy bill in some older buildings. Her company is developing a film that reflects heat and collects water, but the product remains under trial. Experts also warned that not every product delivers its advertised performance.

A light-coloured roof does not have to be white, they said, and reflective solutions should be assessed according to the building, roof material and previous energy use.