An energy audit indicates that a home consumption is 20,000 kWh/year. By using Energy Star appliances and CFLs, a savings of 20% can be achieved for the electrical energy use. The cost for the home retrofit is about \($15,000.\) Assuming that the average energy charge is \($0.09/kWh,\) is the expenditure justified based on a minimum rate of return of 18% before taxes. Assume a 20-year life cycle and use the present worth, annual cost, and rate of return methods.