Insulated vinyl siding: Is it really energy-efficient?

Insulated vinyl siding: Is it really energy-efficient?

When you think of upgrades to make your home more energy efficient, vinyl siding is probably not the first possibility that comes to mind. But if your siding is in need of a curb appeal facelift anyway, consider the value-added benefits of insulated vinyl siding.

According to the Remodeling 2015 Cost vs. Value Report (www.costvsvalue.com), the national average return on investment for foam-backed vinyl siding is 77.6 percent. Add to that the improved energy efficiency for your home, and insulated vinyl siding can be an economically savvy choice, as well as an aesthetically pleasing one.

Energy-efficiency benefits of insulated vinyl siding

The form-fitted, expanded polystyrene (EPS) backing that is permanently integrated into insulated vinyl siding can give it an increased R-value -- the measure of its insulating value -- of between R-2 and R-3. How can that improve the overall energy efficiency of an existing home?

The Insulated Siding Energy Performance Study conducted in three U.S. climate zones by Newport Ventures Inc. for the Vinyl Siding Institute (VSI) retrofitted five homes to find out. VSI reports the results of that study in their June 2013 publication, "Insulated Siding as Home Insulation." The home retrofits in the study demonstrated the following energy efficiency changes after the installation of insulated vinyl siding:

  • Air tightness: Among the homes tested, the air tightness improved an average of 11 percent.
  • Energy savings: Utility bills decreased an average of 5.5 percent. Additionally, some of the home's occupants reported improved comfort levels and less drafts.

Thermal bridging

A home's framing, which accounts for approximately 25 percent of its surface area, can contribute to a substantial loss of heat in winter due to thermal bridging -- the transfer of heat through the framing, which is extremely conductive. The Environmental Protection Agency (EPA) and the 2015 International Energy Conservation Code (IECC) recognize insulated vinyl siding for its ability to reduce thermal bridging and for exterior use on new home construction to increase the total R-value of the home's wall insulation. It can help qualify homes under the ENERGY STAR Qualified Homes Program, as well as meet current energy codes.

Drying capacity

Another study, by the National Association of Home Builders (NAHB) Research Center, conducted in Maryland over a period of 22 months was designed to test the drying capacity of vinyl siding in wood-framed homes in a mixed-humid climate -- in particular, would it retain moisture after a significant storm? Insulated vinyl siding proved no loss of drying capacity due to its foam backing, which they concluded may have actually improved its drying capacity by keeping the wall cavity warm.

While improved energy efficiency may vary, proper installation can yield best results. Existing siding should be removed and any moisture issues should be resolved first. A water-resistant barrier is necessary to prevent moisture intrusion, and the siding must be installed directly over it and the sheathing, not to the furring strips, to qualify as home insulation.

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