estimate the annual operating cost for a heat pump that delivers 40,000 btu per hour of heat during winter and a similar rate of cooling during summer. assume the heat pump operates 8 hours per day for 120 days in summer, and 12 hours per day for 120 days in winter. the seasonal energy efficiency ratio (seer) for summer cooling is 16 btu/wh, and the heating season performance factor (hspf) for winter heating is 12 btu/wh. the cost of electricity is $0.25/kwh.