An environmentally friendly 3 comma 000 3,000-square-foot green home (99% air tight) costs about 8 8% more to construct than a same-sized conventional home. most green homes can save 16 16% per year on energy expenses to heat and cool the living space. for a $ 270 comma 000 270,000 conventional home with a heating and cooling bill of $ 3 comma 500 3,500 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 12 12% per year, and the expected life of the home is 35 35 years.