- Closed-loop heat pump: A heat pump system that uses a loop of a buried plastic pipe as a heat exchanger. Loops can be horizontal or vertical.
- COP (Coefficient of Performance): The ratio of heating provided by a heat pump to the energy it consumes. Higher COP equals higher efficiency.
- EER (Energy Efficiency Ratio): The ratio of cooling provided by a geothermal heat pump to the energy it consumes. Higher EER equals higher efficiency.
- Fossil fuel: Any of several types of combustible fuels formed from the decomposition of organic matter. Examples are natural gas, propane, fuel oil, and coal.
- Geothermal heat pump: A heat pump that uses the earth as a heat source and heat sink.
- Heat exchanger: A device designed to transfer heat between two physically separated fluids or mediums of different temperatures.
- Heat sink: The medium – air, water, or earth – which receives heat rejected from a heat pump.
- Heat source: The medium – air, water, or earth – which receives heat is extracted by a heat pump.
- Open-loop heat pump system: A heat pump system that uses groundwater from a well. The water is returned to the environment.
- Compressor: The compressor increases the pressure and temperature of the refrigerant and simultaneously reduces its volume causing the refrigerant to move through the geothermal heat pump to facilitate heat transfer between the air in your home and the heat pump.
- Payback: A method of calculating how long it will take to recover the difference in costs of two different heating and cooling systems by using the energy and maintenance cost savings from the more efficient system.