Historic El Nino Threatens Heat Records, Reflective Roofs Offer Energy-Saving Solution

Extreme heat waves driven by a historic El Nino in the Pacific Ocean are predicted to bring record temperatures to Australia and several other regions, including Southeast Asia. Amid that threat, a simple yet effective approach is emerging: coating roofs with heat-reflective paint. This step not only lowers indoor temperatures but also significantly cuts cooling energy consumption.

Data from Australia's CSIRO shows that most home roofs in the country are dark or medium-colored, even though light colors reflect heat more effectively. Similar conditions are common in densely populated areas of Indonesia, where concrete and dark clay tile roofs dominate. As a result, houses become ovens for their occupants, and electricity bills soar as air conditioners work extra hard.

The experience of Nic Jacobsen, a renewable energy engineer in Adelaide, proves the point. After improving insulation, heat still radiated from the metal roof and west wall of his home. "The west wall especially gets direct sunlight, and because the second floor has no trees or buildings shading it," he said. After applying heat-reflective coating to the roof and walls, the change was immediate. He said his air conditioning bills dropped drastically, though he did not calculate the exact figure.

Prof Sebastian Pfautsch of Western Sydney University, a leading researcher on cool roofs, highlighted that many homeowners are stuck with dark roofs, especially cement-based ones that have high thermal mass and therefore cool slowly. He recommends reflective coating as a first step before installing solar panels or improving insulation. "Solar panels become less efficient if they are too hot, so installing them on a dark roof that absorbs heat is a waste," he said. "Once your roof is light-colored, solar panels work more effectively."

Prof Chiara Neto, a physical chemist at the University of Sydney, has developed a reflective film that can reflect 96% of solar heat while also capturing water. Her startup, Dewpoint, is testing the product in the Middle East, Asia, and Australia. "Roof coating is one of the most efficient and inexpensive ways to keep homes cool," she said. She estimates electricity bill savings could reach 40%, especially for older buildings.

Although promising, consumers need to be cautious. Pfautsch warned that not all products live up to their claims. In 2016, Dulux was fined AU$400,000 over unfounded claims about the cooling ability of two of its paints. "I don't own shares or act as a sales agent," he said, naming Super Therm as one product worth considering. Super Therm, a water-based ceramic paint developed by NASA for the space shuttle, rejects infrared radiation so roofs do not absorb heat.

For Indonesia, which is frequently hit by high temperatures and relies heavily on electricity for cooling, this technology offers a major opportunity. The government can encourage adoption through fiscal incentives or green building regulations. Property developers can also integrate reflective roofs as a standard, reducing the load on the power grid and carbon emissions. In addition, labor-intensive roof coating programs can create jobs while improving urban climate resilience.

Going forward, the question is no longer whether this technology is effective, but how quickly it can be adopted in tropical countries. With El Nino predicted to strengthen, investment in reflective roofs could be a pragmatic step to protect households from extreme heat and soaring energy costs. Will Indonesia take a lesson from Australia and make cool roofs a national priority?