- Posted by: Ana
- Category: Energy Efficiency
When I first heard the term “cool roofs,” what leapt to mind was “Hey, maybe that’s why Frisbees and wiffle balls like to hang out up there.” But then I discovered that these roofs weren’t cool as in all the girl frogs saying “That Eco, he’s so cool…”. Instead, these special roofs are cool temperature-wise thanks to some amazing new technology in roofing materials.
There are two factors that define a cool roof–solar reflectance and thermal emittance. Solar reflectance refers to a roof’s ability to reflect the sun’s heat. Today, many of the products designated cool roofs utilize innovative new granules that can reflect back up to four times more of the sun’s rays than traditional materials do! Thermal emittance, on the other hand, is the capacity for a roof to radiate heat that has been absorbed back into the atmosphere.
Cool roofs generally excel in both of those areas so that the roof literally stays cooler and transfers less heat to the building below. That naturally results in a more comfortable living space. It’ll also makes your air conditioning not have to work nearly as hard, and will save you an average of 7 to 15% on your cooling costs. Pretty cool, huh?
Another principle that helps make cool roofs cool is what I like to call the “T-shirt effect.” Everybody knows if you wear a black T-shirt on a hot summer day, you’ll be a lot hotter than you would if you opt to wear a white one instead. That’s because dark colors absorb heat and light colors reflect it.
Now that’s not to say that a cool roof needs to be white. There are a lot of “cool color” technology products that come in a wide array of hues including darker pigments that are highly reflective in the near-infrared, invisible-to-the-eye portion of the solar spectrum. Believe it or not, there are even “cool black” roofs.
So how do you know if a roof is cool? That’s where the cool cats at the Cool Roof Rating Council come in. An independent, non-profit third party organization, the CRRC rates roofing materials for solar reflectance and thermal emittance. The scale for both is from 0 to 1–with 1 offering the best reflection and emission. Those results are then published online, free-of-charge for everyone to see. To compare products for yourself, just go to coolroofs.org. Or ask your friends at Excel Roofing about it. They’re members of the council, too.
Another frog-blog will be coming soon. In the meantime, by all means, keep it cool.Excel Roofing is a Denver roofing company with 20 years experience.