Many North Texas property homeowners fret over the energy costs of maintaining a comfortable indoor temperature. While most stress more over heat concerns than winter weather, many of them fail to realize that the same application that addresses unwanted heat and cool air loss in the summer can provide the benefit of keeping the warmth in and the cold out in the winter months. Radiant barriers, a rapidly growing option within the energy savings industry for both new home and retrofit applications, is becoming an environmentally friendly system to lower energy costs and increase energy efficiencies.
A radiant barrier is typically a highly reflective material, like aluminum or metallic foil, that blocks or reflects heat transfer by thermal radiation. Because all materials emit energy by thermal radiation as a result of their temperature, the amount of energy radiated is dependent upon the surface temperature (emissivity) and reflectivity of the material.
Especially intense in the country’s southern regions, summer heat generates solar energy that is absorbed by the roof and heats the roof sheathing, causing the underside of the sheathing and the roof framing in the attic to become hot. These surfaces then radiate heat downward toward the attic floor. Radiant barriers reduce that energy flow by blocking the heat transfer and so reduce the amount of solar energy reaching the attic floor. The attic’s surface temperatures are lowered, including the heat transfer to attic insulation, for an overall reduction of attic air temperature.
By measuring the percentage of energy, or heat, that is intercepted by the barrier and reflected outward, barriers can be evaluated on performance and whether they meet energy code requirements established by agencies such as the U.S. Department of Energy (DOE) which establishes guidelines for Energy Star certification. Third-party verification is conducted through testing by associations such as the Reflective Insulation Manufacturers Association (RIMA) and American Society for Testing and Materials (ASTM). In order for radiant barriers to meet code and testing specs, they must have a minimum reflectivity measurement of 90 percent and an emissivity rating of 0.1 or less.
Three Barrier Types
Radiant barriers come in a variety of forms, with the three most popular being reflective radiant barrier paint, reflective laminated roof sheathing and reflective foil sheet. Each uses reflective aluminum material, with the major difference being how the barrier is installed. No matter the type of barrier, its effectiveness depends upon proper installation and the need for the barrier to face an open air space through which heat would otherwise flow.
Radiant barrier paint or interior radiation control coatings (IRCC) are sprayed or brushed directly onto the underside of rafters and conventional oriented strand board (OSB) roof sheathing. IRCC may be applied to the interior side of exterior walls, as well. Due to variables in the application, effectiveness and results may vary.
Radiant barrier that is laminated or bonded directly to roof sheathing during manufacture is typically used for new construction and can be found in a variety of sheathing materials, with barrier on one or both sides. This application can deflect a large amount of heat from penetrating through the roof and is a straightforward application, resulting in sheathing and a barrier being applied at the same time and making it a popular choice for new construction.
Radiant barrier foil is manufactured as a roll of highly reflective, double-sided aluminum or metalized sheeting, which is available with or without perforations for breathability. Because the barrier foil is stapled under the rafters and crawlspaces, it can be installed either during new construction or as a retrofit on existing homes. Foil barriers may have a higher install cost as a retrofit, but recent tests show that radiant barriers applied to the rafters are the most cost-effective method and the application preferred by DOE for installing retrofit radiant barriers.
Energy Attic, a North Texas company specializing in energy-saving products, utilizes a foil barrier insulation system. Owner Ryan Amerson says, “We have found foil radiant barrier to be an effective component of a full insulation system in permanently reducing energy costs. We use a durable, double-sided 99 percent pure aluminum foil that is stapled under the rafters and crawlspaces that has been tested to reflect 97 percent of the radiant heat. We’ve seen owners experience up to 40 percent lower energy costs and enjoy a more comfortable living area, since the barrier helps keep temperatures consistent throughout the home.” A full insulation system can reduce attic temperatures by 40 to 50 degrees in the summer, ultimately reducing the temperature of your ductwork and allowing your air conditioner to operate more efficiently.
Radiant barrier is not an insulator, but when installed correctly and utilized as part of an insulating system, it can increase the insulation effectiveness and indirectly contribute to maximizing the R-values of insulation components. “We propose a three component insulation system approach,” says Amerson. “Our foil barrier prevents radiant heat from entering or escaping; reducing the energy spent on heating and cooling. Adding loose-fill fiberglass insulation to the recommended specifications keeps your cool air from escaping into the attic. Soffit vents or a solar-powered attic fan increases air flow to keep the heat out of the attic away from the barrier. Each component complements one another, maximizing their effectiveness in producing a comfortable living environment and energy savings.”
Because each building is unique, seeking an energy efficiency expert is the first step in understanding what type of barrier and insulation system will work best for any situation. Be sure the products meet the energy efficiency standards set by EPA and DOE to qualify for federal tax credits.
Energy Attic installs and services radiant barriers, solar attic fans, attic insulation, attic tents and more in tailoring an energy reduction system for your home or business. For more information or to schedule a free estimate, call 972-548-0088 or visit EnergyAttic.com.