It’s heating up outside and homeowners are looking for ways to reduce air conditioning costs and maintain a comfortable interior temperature. Specifying insulated siding can help reduce energy loss, keeping homes cool in the summer and warm in the winter. With vinyl siding already the top residential exterior cladding used, according to the U.S. Census Bureau, insulated siding may be a good fit to help homeowners looking to save resources in both re-siding and new construction projects.

Insulated siding, or vinyl siding with rigid foam insulation that is integral to the panel, is recognized by energy codes and green building programs alike as a form of continuous insulation. Insulated siding is proven to reduce thermal bridging, or the transfer of energy between framing materials. To help builders, designers and energy raters understand insulated siding’s R-value, product testing and various applications to ensure this cladding delivers energy savings as part of a whole wall assembly, the Vinyl Siding Institute, Inc., a trade association representing vinyl and other polymeric siding manufacturers and suppliers to the industry, has developed Insulated Siding as Home Insulation: Guide for Users and Energy Raters.

Measuring Insulation Effectiveness
With more than a decade on the market, insulated siding has evolved both in terms of design and manufacturing, allowing it to be recognized as a home insulation and thermal bridge reducer. Insulated siding is now recognized as continuous insulation in both the International Energy Conservation Code (IECC) and in ENERGY STAR^® Qualified Homes. To qualify under energy codes and green building programs, proper testing of insulated siding R-value is critical.

Like other insulating products, performance of insulated siding is rated by R-value, a measure of thermal resistance. The higher the R-value, the better the insulation’s effectiveness. Insulated siding R-values are tested according to ASTM C1363 Standard Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus, in a dual chamber assembly with wind directed perpendicular to the siding to simulate winter conditions.

The 2012 IECC includes insulated siding as one of the materials that can be used as continuous insulation outside of the building framing to provide the required total wall R-value for buildings in the coldest climate zones.

Siding That Saves
The U.S. Environmental Protection Agency’s ENERGY STAR Qualified Homes and the U.S. Department of Energy’s Builder’s Challenge use a home energy rating system (HERS) to develop a score to rank and rate a home’s energy performance. The lower the HERS Index, the better the building’s energy performance. Insulated siding has been shown to account for a one to three point HERS Index improvement compared to a new, 2009 IECC minimally compliant home. This improvement on a 2009 IECC minimally compliant home can help account for up to 23 percent of the HERS Index improvement needed to qualify under ENERGY STAR Qualified Homes Version 3 for new homes.

For existing homes, adding insulated siding reduces heating and cooling energy use by 1 to 4 percent. In fact, installing insulated siding will save about 5.5 times more energy than replacing a pre-1993 refrigerator with a more energy-efficient model.

In a study conducted as part of the New York State Energy Research and Development Authority’s High-Performance Residential Development Challenge, VSI commissioned Newport Ventures to compare the thermal insulation of insulated siding and James Hardie fiber cement siding. Using infrared technology, Newport found that insulated siding on the home was cooler than the fiber cement siding, demonstrating less heat loss. Newport also found insulated siding, compared to fiber cement siding, saved 3.2 million British thermal units (Btu), 488 pounds of carbon dioxide associated with that energy use and $56 per year in natural gas and electric utility costs.

Installing for Performance
As with any cladding product, proper installation is key to insulated siding’s performance. VSI has created tools to help build installers’ and specifiers’ confidence about insulated siding’s energy performance. Insulated Siding as Home Insulation: Guide for Users and Energy Raters details installation tips specific to insulated siding, presents data on insulated siding R-values under various codes and programs, and illustrates sample wall assemblies that can help meet or exceed minimum energy code requirements.

Many installation techniques for insulated siding are the same as those of traditional vinyl siding; see the VSI Vinyl Siding Installation Manual available at www.vinylsiding.org for more general installation tips. Insulated siding-specific installation tips include the following:

• With foam integral to the panel, insulated siding is thicker than vinyl siding alone. Be sure to purchase accessories that will accommodate the full thickness of insulated siding.
• Use starter strip specified by the insulated siding manufacturer to ensure performance.
• Insulated siding is not a water-resistive covering. A weather-resistive barrier should be installed underneath.
• No gap is needed between the foam at the ends of insulated siding panels. Be sure to butt each piece of foam together, unless installing in cold weather.
• On the factory-cut ends of insulated siding, the foam is set back from both ends of the panel to ensure correct overlapping of the adjacent panel. Insert the vinyl tab at the end of one panel in between the foam and vinyl of the adjacent panel. Slide the panels together until the ends of foam touch.

If hiring a siding contractor for insulated siding jobs, look for installers and installer companies certified through the VSI Certified Installer Program. VSI Certified Installers have demonstrated knowledge of proper vinyl siding installation techniques per ASTM D4756 Standard Practice for Installation of Rigid Poly(Vinyl Chloride) Siding and Soffit. VSI Certified Installer Companies have independently reviewed quality control programs in place and a VSI Certified Installer or Trainer present on every job crew where vinyl siding is installed. Find VSI Certified Installers and Certified Installer Companies or learn more about becoming certified at www.vinylsiding.org/certifiedinstaller.

To learn more about insulated siding and to download a free copy of Insulated Siding as Home Insulation: Guide for Users and Energy Raters, visit www.insulatedsiding.inf