So what is a cool roof? I have been hearing the term used more and more around Denver lately, but wasn't sure the details of it. It turns out, the term "cool roof" simply refers to a lighter shade roof that reflects the heat from the sun instead of absorbing it and heating thehouse it covers. While black surfaces such as traditional built-up asphalt shingle roofs can reach 185 degrees, a roof that's white can be up to 70 degrees cooler because it bounces so much sunlight back into space.
The science of "cool roofs" is pretty basic. By using roofing materials that reflect more sunlight than they absorb, homes stay cooler in the summer and the need for air conditioning is reduced, thus eliminating the vast amount of electricity we drain each summer cooling our homes. It's such a simple, smart idea that Energy Secretary StevenChu endorsed the idea in a meeting with Nobel laureates last year.
While saving electricity is great for the pocket book, the impact this simple change can have on the environment is exponential. According to a terrific article on cool roofs on MSN right now, click here, with a cool roof less of the sunlight that hitsthe roof is transformed to heat, and so less heat is transmitted to the air. That reduces smog and makes you and everyone else healthier. For every 100 square feet of roofing that's converted from dark to white is equivalent to offsetting the emission of one ton of carbon dioxide. For a 2,000-square-foot roof, that's like 20 tons of atmospheric carbon offset. A worldwide installation of white roofs on low-sloped and colored roofs on sloped roofs in hot and temperate cities of the world will offset the emissions of all the cars in the world for the next 10 to 12 years.
These numbers are pretty staggering in terms of helping the environment. So now the question becomes, is it affordable and would it work in Denver? Cool roof products can cost little to no more than old-school products. The EnvironmentalProtective Agencyestimates that the cost premium for cool-roof products ranges from zero to 20 cents per square foot. Some companies, like Custom-Bilt Metals,can addreflective pigment to even dark colored roofs, thus providing morecolor options to the white roof adverse.Theysay that the reflective pigments add only about five cents per square foot to the finished product, which pays for itself within three years because of the building energy savings.
Since it is very affordable, would it then make sense to install these roofs in Colorado where the a/c is run only a handful of months a year? According to the article, there is, a so-called "heating penalty" for having a white or cool roof, because in winter the roof doesn't keep the house as warm. The wintertime penalties of a white roof can become as much as 30% of the summertime savings.
Here is the bottom line: In any building that requires AC in the summer and heating in the winter, by having a cool-colored roof or a white roof, you'll save money. If you do not need any air conditioning at all such as some residences in northern Alaska and comfort is not an issue for you, you do not need a white roof. The last time I checked, the climate in Denveris a little different than Alaska.So the next time you have to replace a roof, why not look into a cool roof?You can save some money and as the article states, definitely help save our great planet.
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