May 2013 EnergyWiseSM Tip: Radiant Barriers
Have you received a postcard in the mail lately with one of the following marketing lines?:
 Did you enjoy paying your utility bills this month?
 Did you know you may be paying up to 40 percent too much every month?
 See what the Utility Companies may not want you to know!!!
 Free Steak Dinner!
 This technology was developed by NASA and is now being introduced to the general public!!!
Lately, a few companies have been using these lines to convince you to consider installing a radiant barrier or radiation control coating. But will these actions provide significant energy savings in your home?
On a sunny summer day, solar energy is absorbed by the roof, heating the roof sheathing and causing the underside of the sheathing and the roof framing to become hot. These surfaces then radiate heat downward toward the home. Radiant barriers reduce that energy flow. Because the amount of heat radiation striking the top of the home’s attic insulation is less than it would have been, the insulation surface temperature is lower and the heat flow through the insulation is reduced. By reducing the heat energy reaching the attic floor, radiant barriers also reduce the attic’s ambient air temperature.
In the winter, radiant barriers can reduce indoor heat losses through the ceiling, especially during winter nights when the roof surface is coldest. However, radiant barriers also reduce beneficial daytime heat gains due to solar heating of the roof. Depending on your climate, level of attic insulation, and other factors, the net winter effect can be positive or negative.
So what kind of savings can you expect in Nebraska? Oak Ridge National Laboratory (ORNL) is a multiprogram science and technology national laboratory managed for the U.S. Department of Energy. ORNL’s calculations in Nebraska’s weather zone (Zone 5) shows savings varies from $0.00 to $0.03 per square foot. For the typical 1,540 square foot attic in a Nebraska home, the first year’s savings would vary from $0.00 to $61.60 . Considering installation could cost more than $2,000, it may be more than 30 years for your energy savings to pay for the improvement. Detailed results of ORNL’s findings can be found at http://www.ornl.gov/sci/ees/etsd/btric/RadiantBarrier/RBFactSheet2010.pdf
Even so, if you determine that a radiant barrier is appropriate for your attic, make sure the product you install has an appropriate permeability rating to allow any moisture to “travel” through the barrier into the attic where it can be vented out of the home. In Nebraska, barriers are often laid atop the home’s existing attic insulation, with the reflective side up. Although this is the simplest installation method, there are several disadvantages:
•Dust will settle on the reflective side of the barrier, decreasing its effectiveness.
•Traffic (if the attic is used for storage) will damage it.
•Moisture can be trapped where it will soak the insulation and potentially lead to mold problems.
•Kitchen and bathroom vents and recessed lights should not be covered with the radiant barrier.
Your local utility and Nebraska Public Power District want to help you make the most of the energy they provide you. For assistance on making your home EnergyWiseSM, contact your local utility or visit www.nppd.com.