Green insulation for new homes and additions

Posted by Woodrow Aames ~ January 9, 2012

Structural insulated panels (SIPs) are among the latest green design building systems used for residential construction. SIPs are panels manufactured with a foam insulating core packaged between oriented-strand board skins. The resulting sandwich is durable, high in energy efficiency and may even reduce the scale of the systems used to heat and cool your home.

Since building heating and cooling systems account for upwards of 39% of the total U.S. energy consumption, energy efficient home design stands at the construction frontier. SPIs create a tighter, sealed thermal envelope for the home, and they could dramatically reduce the amount of residential carbon dioxide emissions. It takes 24% less energy to manufacture SIP insulation than it does to create an equally insulating fiberglass product.

Green building with SIPs

SIPs are sold as 4- to 8-inch thick foam board insulation and exterior boards that can be modified to homeowner specifications. Traditional insulation products add to the 7,000 lbs. of waste attributed to the building of a 2,000 sq. ft. home. The use of computer design software allows SIP makers to produce sections without excessive waste, helping cut the loss of materials common to construction sites. Scrap materials from SIPs can be reused and built into new panels.

According to the U.S. Department of Energy (DOE), SIPs consistently offer high R-values for insulation and have "high strength-to-weight ratios." Oak Ridge National Laboratory blower door tests showed that a four-inch R-14 SIP wall outperformed 2×6 stick framed wall insulated with R-19 fiberglass.

The oriented strand board (OSB) panels used to sandwich the SIP foam center are typically manufactured from fast-growing small wood chips harvested from managed forests. The DOE reports that many manufacturers make and ship pre-cut "panelized housing kits", allowing for quick installation. Builders can cut out openings for doors and windows on the construction site.

For those with pest or fire concerns, boric acid-treated insulation panels are solid options that address both issues. Fire investigators told the DOE that OSB panels perform well.

Other SIP insulation materials

The greenest fill for an SIP is straw, manufactured from renewable agricultural products. On the negative side, straw is a heavier core material than the expanded polystyrene fills which use a lot of air to fill the product. Compressed straw also offers less insulation for the thickness of the fill than polyurethane derivatives.

People often ask, "How do I choose the best home insulation?" That depends if you're adding insulation or building something new. You'll find wider options than ever before -- if you're creating an addition or building a green home.

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