If you’ve ever been to the Mediterranean or watched a program about it on television, you may have seen neighborhoods full of homes with white-painted roofs. Cool roofs have been used to cool homes since ancient times in places like Greece, and are becoming popular in places like New York, California and Hawaii.
Since white is a poor radiator of heat, white-painted roofs can help keep your home cooler by reflecting the sun’s energy away from your home and preventing it from radiating into your attic and down into your living space. But there’s a lot more to installing a modern cool roof than just painting your roof white, and modern cool roofs offer more benefits than simply saving money on your monthly electric bills.
The Benefits of Cool Roofs
Although most modern cool roofs are white, it’s the solar reflective surfaces of the materials used in the roofs — whether those materials are reflective paints, sheet coverings or reflective tiles or shingles — that make the real difference. In fact, standard roofs can get as hot as 150 degrees in the summer, but cool roofs under the same conditions could stay more than 50 degrees cooler.
Such a significant difference in roof temperature can benefit you in several ways:
- Reduce your monthly electric bills by decreasing the need to use your air conditioner to maintain a comfortable indoor environment
- Improve the comfort of spaces in your home that aren’t air conditioned
- Extend the life of your roof by decreasing its average operating temperature
Installing a cool roof can also benefit your neighbors and the environment, especially when whole neighborhoods use them:
- Reduce local air temperatures by mitigating a phenomenon known as the urban heat island effect
- Decrease peak energy demand, which, in many urban areas, can help prevent power outages
- Reduce power plant emissions — such as carbon dioxide, sulfur dioxide, nitrous oxides and mercury — by decreasing the amount of electricity you use in your home
4 Questions You Should Ask About Cool Roofs
There are four basic questions you should ask about cool roofs before you decide if a cool roof is right for you:
1. What are the project requirements for installing a cool roof?
From the materials that you can use — such as coatings, membranes, shingles or tiles — to the grade of slope of your roof, there are many types of installation or retrofitting options to consider when it comes to cool roofs. To determine which options are best for you, consider scheduling a consultation with a cool roof installer in your area.
2. What are the building regulations for a cool roof on my home?
Building codes for your city and neighborhood can help you determine if a cool roof is permissible and what restrictions there are regarding materials and installation. Websites for your local state, city or municipality are likely to have the necessary information, as might a local builder or local cool roof installer.
3. Is the amount of energy saved by a cool roof worth the cost of installing one?
Simply painting your roof white could reduce your air conditioning costs by 20 percent, and installing a complete cool roof could save even more. But like most energy efficiency home improvements, up-front expenses will outweigh savings until material and installation costs are eventually recouped by saving money on monthly utility bills. The U.S. Department of Energy offers a complex online cool roof calculator to help you determine how long that might be, but a local cool roof installer might be able to provide you with a simpler estimation.
4. Is my climate right for a cool roof?
Homes in warm climates benefit from cool roofs more than homes in cool climates. In fact, cool roofs on homes in cool climates can sometimes have the undesired effect of costing homeowners more in heating costs than it saves them in cooling costs. But cool roofs can also be problematic in warm climates since they’re more susceptible to algae or mold growth than normal roofs that get very hot in the summer and kill algae and mold before it has a chance to grow. Make sure to ask your installer about cool roof coatings that prevent algae and mold from growing.
Cool Roof Rating Council website, “Cool Roof Codes and Programs.”
Energy Savers website, “Cool Roofs.”
Energy Savers website, “Deciding Whether to Install a Cool Roof.”
Energy Savers website, “Types of Roofs — How They Can Be Made Cool.”
Oak Ridge National Laboratory website, “DOE Cool Roof Calculator.”
U.S. Department of Energy report, “Guidelines for Selecting Cool Roofs,” July 2010.
“White Roofs Catch On as Energy Cost Cutters,” The New York Times, July 29, 2009.