Having a “cool” roof is pretty hip – but that’s not only what “cool” means in this case! Cool roofing refers to the use of thermal roof coatings that reflect sunlight away from the house, rather than absorb it, as a way to moderate building temperatures and reduce the amount of energy needed for home heating. In this era of increasing energy costs and growing concerns about the environmental impacts of burning fossil fuels, cool roofs – known as thermally coated roofs in the UK - make sense because they save energy and money and help slow climate change. Here is more information on cool roofs, thanks to Improve a Roof, our sponsors for this post.
Any surface exposed to solar energy will get hot. Traditional roofing materials absorb 85 to 95 percent of the solar energy that reaches them, increasing the temperature of the rooms below. Thermally coated roofs reflect more of that energy back out into the atmosphere.
A cool roof offers several important benefits. Because it transfers less heat to the building below, the building requires less energy for cooling, a big advantage in the summer when many homeowners max out their air conditioning – and their electricity bills. By some estimates, a thermally coated roof can reduce a homeowner’s electricity demand by 14 to 38 percent (depending also on how well the roof and home are insulated, among other factors).
Most electricity is generated by coal-fired power plants. Burning coal creates air pollution and carbon dioxide that causes climate change. Because cool roofs reduce electricity demand, they also help keep the air clean and help minimize climate change.
Plus, cool roofs can increase comfort for the people living in them, especially in homes that do not have air conditioning. In the picture above, the bottom photo shows how much energy (heat) is being absorbed on an untreated roof, compared to the top photo of the same roof that's been thermally coated.
Brand new, or retrofit?
Cool roofs can be installed on new construction, but homeowners can also retrofit their existing roofs by working with a contractor to apply coatings or membranes.
What is a cool roof made of?
There are generally two types of roofs –low-sloped, and steep slopped. A low-sloped roof is mostly flat, with only enough incline to provide drainage; it’s normally used on commercial, industrial, warehouse, office, retail and multi-family buildings. Most homes have a more steeply sloped roof. The kind of roof usually determines what materials can be used to make it cool. Contractors can use surface treatments like thermal coatings that reflect the sun’s rays, restrict the growth of algae, and are waterproof. They can also apply membranes, pre-fabricated sheets applied in a single layer (these are better for a flat or low-sloped roof).
What will it cost?
If you’re interested in making your roof cool, get bids from contractors like Improve a Roof who can also tell you what thermal roof coatings are appropriate for your home. Don’t forget to factor into the cost the amount of money you will save on cooling your home in the summer. Some communities may provide tax credits for installing energy-saving technology, which will add to the savings.
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