Spray in foam insulation is relatively new as far as home building products go. Spray foam insulation is applied between the wall studs of a new home and insulates much the same way as an ice chest does. It seals up cracks between boards and voids much better than fiberglass insulation and provides a higher R value. One variation of spray foam insulation that is eco friendly and has no offgassing issues is soy based spray in foam insulation. It is a natural polyurethane foam made from soybeans.
The question is, “is soy based spray foam insulation worth spending twice as much for?”.
The answer to this question depends on a number of factors such as how large the local, state or federal rebates are for energy efficient products and how much your local gas and electric rates are. In places where the winter temperature regularly goes below 20 degrees Fahrenheit, spray foam insulation may save as much as half on heating costs. In areas where the summer temperatures regularly go above 95 degrees you can expect to save about half on cooling costs versus a home insulated with fiberglass insulation.
The other factor is are “green homes” something that can command an higher resale value in your area? In some eco conscious cities like Austin Texas and San Francisco California, green homes can command up to a ten or twenty percent higher resale value.
For more on spray foam insulation see SaveGreenly.com