10-2. An environmentally friendly 2,800- square-foot green home (99% air tight) costs about 8% more to construct than a same-sized conventional home. Most green homes can save 15% per year on energy expenses to heat and cool the living space. For a $250,000 conventional home with a heating and cooling bill of $3,000 per year, how much would have to be saved in energy expenses per year to justify this home (i.e., B–C ratio greater than or equal to one)? The discount rate is 10% per year, and the expected life of the home is 30 years. (10.7)