The east wing of the building is heated by a ground source heat pump, which pulls heat out of the earth by running fluid through underground coils. We installed the system two years ago to study how heat pumps work in extremely cold soils, in a project funded by the Alaska Energy Authority and the Denali Commission. This winter it had an efficiency of 3.3, meaning for every 1 unit of energy needed to run the heat pump, it produced over 3 units of energy. But the system is slowly losing efficiency as we take more heat out of the ground each winter. You can find more info on our heat pump here, and we’ll continue to study it for a full decade. View Two Year Performance