For a 15-m × 20-m one-story house located in San Francisco, CA, determine the cost-effectiveness of retrofit of the windows with SISs. The house has a BLC of 500 W/°C, wall height of 3.50 m, and WWR of 50 percent. The cost of window-SIS retrofit is estimated to $25/m2 of window area. Assume the house is heated and cooled with a heat pump with COP_H = 2.5 for heating and COP_C = 4.0 for cooling. The analysis can be carried out using the LCC approach with a lifetime of 30 years and a discount rate of 5 percent. Assume that the electricity price is 0.12/kWh.