What are Radiant Barriers?
The sun heats our roofs and attics through two processes—radiation and conduction—and Florida receives a tremendous amount of sun that can affect the quality of our roofing materials and our cooling costs. Our roofs are heated through UV radiation, a process when heat travels in a straight line from one source to another, and our attics are heated through conduction, a process where a hot surface warms the air on the other side. This conduction heated air then radiates downward onto the surfaces of the attic, including air ducts. Radiant barriers are a type of insulation that uses an aluminum surface to prevent up to 95 percent of conduction heated air from reaching attic surfaces and air ducts. They can potentially reduce your cooling costs by reducing this transfer of heat, and they are most effective in sunny, hot climates where UV radiation is highest.
How Much do They Cost?
According to a report from the Florida Solar Energy Center and the University of Central Florida, “[r]adiant barriers are a new technology, so the market price has not yet found its own level.” But the material costs can range from $0.10/square foot to $0.65/square foot. The costs of installation can also vary widely depending on whether it is a retrofit on an old house or part of a new construction. Retrofit jobs range from $0.15/square foot to $0.35/square foot, while new construction installations range from $0.05/square foot to $0.20/square foot. Retrofit installations tend to cost more because of the limited room to maneuver during the installation.
What are the Benefits? Are Radiant Barriers Worth the Cost?
Radiant barriers can prevent up to 95 percent of heat from radiating to attic surfaces and air ducts, but what effects can this have on your cooling costs? Some installers claim you can save as much as 40 percent on cooling costs, but these figures are grossly exaggerated. The Reflective Insulation Manufacturers Association International claims “savings are difficult to predict because there are many factors that affect energy consumption,” but the FSEC/UCF report and the Department of Energy give more definite answers, although they are not definitive because they differ and range. The DOE claims radiant barriers can save you 5 to 10 percent on your cooling costs, while the FSCE/UCF report claims they can save you between 10 and 15 percent. According to the FSCE/UCF report, “attics account for only about 15% to 25% of the total heat gain into a Florida home, it’s impossible for any attic energy conservation measure to save 40% on the total bill.” So according to their figures, you could save a total of 3 to 6 percent on your entire annual energy bill, but you need to take into account whether your home is in a sunny or cloudy climate and if you have air ducts in your attic or not before you make your decision, because those differences will affect your benefits greatly. But if you live in a sunny climate with air ducts in your attic and you plan to live in your home for a long time, it could be a very wise investment. If your total system costs $0.30/square foot to $0.35/square foot, you could see your system pay you back in 10 years.
You should also ask your roofer how radiant barriers can affect your roofing material. Reflection from radiant barriers has been linked to a greater heat strain on your roofing material. You will want to get all the facts before you make an investment.