Focus on the difference between feasible alternatives (Principle 2)! Insulated concrete forms (ICF) can be used as a substitute for conventional wood framing in building construction. Heating and cooling bills will be about 50% less than in a similar wood-framed building in upstate New York. An ICF home will be approximately 20% more expensive to construct than a wood-framed home. For a typical 1,800ft2 home costing $170 per ft2 to construct in upstate New York and costing $240 per month to heat and cool, how many months does it take for a 1,800ft2 ICF home to pay back its extra construction cost? It will take months to pay back the extra ICF construction cost through monthly energy savings. (Round to the nearest whole number.)