U.S. Department of Energy - Energy Efficiency and Renewable Energy
Energy 101: Cool Roofs (Text Version)
Below is the text version for the Energy 101: Cool Roofs video.
The video opens with "Energy 101: Cool Roofs." This is followed by images of residential rooftops.
Maybe you've never given much thought about what color your roof is, or what it's made of. But your roof could be costing you more money than you know to cool your home or office building, especially if you live in a warmer climate.
The video shows pedestrians walking on a city street.
Think about it this way… in the summertime we wear light-colored clothes because they keep us cooler. Lighter colors reflect — rather than absorb — the heat of the sun.
The video shows images of a white roof.
It's the same with your roof. A cool roof is often light in color and made of materials that have what's called "high solar reflectance."
The words "High Solar Reflectance" appear on the screen.
That means it's able to reflect a lot of the sun's light that a conventional roof would absorb, heating up the building.
An animation shows a large building with a conventional dark roof.
You see… when the weather is warm, a conventional roof is the hottest place on the building… it can be well over 50 degrees hotter than the temperature outside. If you don't have air conditioning, a lot of that discomfort you feel may be coming from the roof.
The animation reveals the interior of the house. Insulation is shown lining the floors of the house.
If a building with a standard darker roof is air-conditioned, the cost for comfort is much higher, in order to counteract all that heat pouring in from above. Insulation slows the transfer of heat inside, but doesn't eliminate it.
The words "10-15% Energy Savings" appear on the screen.
Researchers have measured energy savings up to 10-15% for homes with cool roof coatings. (1)
The video moves to an aerial shot of city roofs, then returns to the house animation.
And if a standard dark roof reaches 150 degrees or more, a cool roof can actually reduce the roof temperature a lot.
The numbers "90°F" and "95°F" appear on the screen above the roof.
A cool roof may only be 5 or 10 degrees warmer than the temperature outside on a hot, sunny day. (2)
The video moves to a shot of a building with a cool roof, then to an aerial shot of a city.
Alright, so here's a big plus for the environment. A cool roof helps mitigate an phenomenon known as the "urban heat island."
The image takes on infrared coloring. The words "Urban Heat Island" appear on the screen. The video then moves to various infrared images of of city roofs.
The temperature in developed, urban areas tends to be two to five degrees warmer than surrounding areas. That's because ground covered by pavement and dark buildings absorbs more heat, so the heat stays in the atmosphere longer.
The video shows an image of a roof with plants growing on top of it. The words "Green Roof" appear on the screen. Images of vegetation growing on soil are shown.
A variation of the cool roof is the green roof—sometimes called a "living roof" because flowers and plants, and even a vegetable garden—grow in a special soil system right on top of the building.
Various images of white cool roofs are shown.
Cool roofs aren't super high-tech, and that's part of their appeal. They're a relatively simple and effective way to improve our environment… and lower energy costs.
From researchers at LBNL and the FL Solar Energy Center as published in Professional Roofing Magazine, Oct. 98.
California Energy Commission Consumer Energy Center.