1-7. 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 10% more expensive to construct than a wood-framed home. For a typical 2,000 ft2 home costing $120 per ft2 to construct in upstate New York and costing $200 per month to heat and cool, how many months does it take for a 2,000 ft2 ICF home to pay back its extra construction cost? (1.2, 1.3)