Our annual cooling and heating savings was $1,220 compared to the same period the previous year. Notes: Heating Degree Days were 3.2% greater than the previous year (without the geothermal system.) Cooling Degree Days were 4.8% less than the previous year (without the geothermal system.) In heating mode, we kept the thermostat 3f warmer during the day, and 8f warmer at night compared to the old system. In cooling mode, we kept the thermostat 3f cooler day and night compared to the old system. Also, with the old system, we would open the windows and run the whole house fan until the outdoor temperature reached 78f-80f. With the geothermal system, we keep the windows shut and still have lower electric bills. I now keep the whole house fan covered and the circuit breaker turned off. Old system was 17 year old Carrier 10 SEER AC and propane furnace for the 1st floor. Second floor was 9 year old Goodman air source heat pump. Savings would also have been much higher had I not shopped around for propane the prior year. We had neighbors paying $4.00/gallon where we paid $2.50/gallon at most. This would have amounted to another $750 of propane savings had I not shopped around. Our old HVAC systems needed replacing. For $10,000 we could have installed two 13 SEER Trane heat pumps. For $17,500 (after the 30% tax credit) we went geothermal. Overall system payback should easily be within 12 total years given inevitable electricity price increases. Rates just increased for us by roughly 20% last month. 7 total years is my best guess on the payback on the $7,500 incremental cost of air source heat pumps. In summary: We're much more comfortable. It's nice not hearing noisy outdoor AC units and heat pumps running and defrosting. The geothermal system should last much longer than an air source heat pump. The system should pay for itself within its useful life. We'd do it again.