Cool Roofs May Turn Down the Heat in China During Heat Waves
Cool roofs in China may keep things at a reasonable temperature during heat waves. Scientists have found that during a heat wave, the use of white roofs has significantly more of an impact than during regular heat.
In this latest study, the researchers used a regional climate model combined with an urban model that allowed them to adjust roof reflectance. This revealed that the average urban midday sun temperature was lowered by 1.2 degrees Celsius during heat waves. This is 50 percent more than the .8 degrees reduction for typical summer conditions.
"The hotter it is, the more cooling you get with cool roofs-and it is a significant difference, compared to the margin of error," said Dev Millstein, one of the researchers, in a news release. "We found that the stagnant conditions of a heat wave, where the air is just sitting over the city, was one of the main factors."
Reflective roofs save energy and keep buildings cooler, which reduces the need for air conditioning. By installing these cool roofs, it may be possible to reduce the amount of energy that's used in a city while at the same time cooling down the city as a whole.
Of course, replacing roofs will take time. However, by doing it one at a time it may be possible to make a major impact on heat and energy use in a city.
The findings are published in the journal Environmental Science & Technology.
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