Radiant barriers and interior radiation control coatings are designed to work in your attic to keep some of the heat from the sun away from your living space. For homes with air-conditioning ductwork in the attic in the deep south (such as in Miami in Zone 1 or Austin in Zone 2), radiant barriers could reduce your utility bills by as much as $150 per year using average residential electricity prices. If you’re able to participate in one of the Time of Day rate plans, your savings can be even greater (almost $200 per year under the current Miami Time of Day rate plan). For milder climates, like those in Atlanta and Baltimore, annual energy savings will be about half those of their southern neighbors. In the northern climate zones, the savings drops further, going from about $40 to $10 per year as you go from Chicago to Fairbanks.
If there are no ducts or air handlers in the attic, the savings are much less, going from about $20 per year in Miami to $5 per year in Baltimore, but a radiant barrier may still help to improve comfort and to reduce the peak air-conditioning load.
What is a radiant barrier?
Radiant barriers consist of a thin layer of a highly reflective material, usually aluminum, applied to one or both sides of another material that provides strength and durability. These other materials include kraft paper, plastic films, cardboard, plywood or oriented strand board (OSB) sheathing, and air infiltration barrier material. Be sure that the label indicates that the product emittance is less than 0.1, as measured by ASTM C1371.
What is an interior radiation control coating?
|An interior radiation control coating is a liquid that is spray-applied to the underside of a roof system. The coating must be applied at a certain thickness, perhaps over a primer coating, to provide the desired performance. Be sure that the label indicates that the product emittance is less than 0.25 as measured by ASTM C1371. Many interior coating products have names that sound like a radiation control coating, but unless the label shows the emittance is between 0 and 0.25, they won’t perform as intended. The rest of this article will refer to radiant barriers, but interior radiation control coatings may apply in many cases. Savings for these coatings may be a little less due to higher emissivity, but that may be counter-balanced if the coatings cover more of the exposed surface than a radiant barrier.|
|Many interior coating products have names that sound like a radiation control coating, but unless the label shows the emittance is between 0 and 0.25, they won't perform as intended.|
If you are a homeowner considering radiant barriers, please read:
- How do radiation barriers save energy?
- Radiant barriers are one component in the attic system
- After you’ve decided to install a radiant barrier product
If you want to learn more about radiant barriers, please read:
- More about heat transfer in attics