|Two materials scientists from Sydney say they’ve had a breakthrough in cool roof technology that could have major implications for cutting energy usage and greenhouse gas emissions in urban areas.“[In our study] we demonstrate for the first time how to make a roof colder than the air temperature around it, even under the most intense summer conditions,” University of Technology Sydney Professor Emeritus Geoff Smith told science news site Phys.org May 28.Smith and colleague Angus Gentle say they accomplished the task by creating a novel roofing surface made of a “coated polymer stack”: certain polyesters on a silver layer.
Dark roofs, such as those covered in asphalt shingles, absorb heat. Asphalt shingles are the most common choice across North America largely because they’re affordable and durable — lasting between 15 and 30 years — but that heat absorption can become a major problem in densely populated urban areas or in areas that are already quite hot. And even the white roofs that are more common elsewhere absorb enough sunlight to heat up quite a bit, Smith explained.
When they tested their polymer stack roof, however, they found that it absorbed only 3% of sunlight and radiated heat at infrared wavelengths that aren’t absorbed into the atmosphere. That could keep homeowners more comfortable, reduce the amount of energy needed to cool buildings, and ultimately reduce environmental warming as well.
“Much of the world’s population lives in warm climates. Keeping a roof cool saves energy and makes building interiors comfortable in summer. If enough roofs in a precinct are kept cool then the local climate can also be beneficially influenced,” Smith summarized.
And although it’s not known when the technology could break into the competitive roofing and roof coating market, Smith noted that the plastics they used were readily available and may be well suited for general roofing tasks.
The full study was published in the latest issue of the journal Advanced Science.
As the Washington Post recently reported, the Australian pair’s technology isn’t the only approach to creating cooler roofs. Green roofs — ones covered with living grasses and other plants — can reduce heat retention, cool buildings, lower energy use and even reduce carbon dioxide concentration. Plus, new research has shown there may be significant psychological benefits for urbanites who are exposed to even such small “doses” of nature.