Question: Insulated concrete forms (ICF) can be used as a substitute for traditional wood framing in building construction. Heating and cooling bills will be about 50% less than in a similar wood-frame home in Vermont. An ICF home will be approximately 10% more expensive to construct than a wood-frame home. A typical 2,000 square foot home costs $120 per square foot to build with wood framing in Vermont and costs $200 per month (on average) to heat or cool. What is the IRR on the incremental investment in an equivalent-sized ICF home? The home's residual value with both framing methods in 20 years is expected to be $280,000.