published on | 02 Dec 2017
The energy performance of cool roofs has been clearly demonstrated in both the lab and in utility bills for buildings that have them, and they also help keep urban areas cooler by reflecting sunlight. Research at the Department of Energy’s Lawrence Berkeley National Laboratory now suggests that widespread adoption of cool roofs can also reduce the quantity of water needed for urban irrigation.
Berkeley Lab researchers Pouya Vahmani and Andrew Jones used regional climate simulations of 18 California counties to find that cool roofs could reduce water consumption by as much as 9% if implemented widely. The study, which appeared in Nature Communications, suggests that in Los Angeles County alone, water savings from irrigation could reach 83 million gallons per day if all buildings had reflective roofs.
“This is the first study to look at the link between water and heat mitigation strategies in urban areas,” says Vahmani. “You might not do cool roofs just to save water, but it’s another previously unrecognized benefit of having cool roofs. And from a water management standpoint, it’s an entirely different way of thinking – to manipulate the local climate in order to manipulate water demand.”
By reducing the ambient air temperature by 1.8-2.7 degrees F. in the study, cool roofs reduce water consumption because lawns and other landscaping need less water, according to the study. The scientists also contend that modification of human behavior may be needed to fully realize this water saving potential.
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