Glossary · Heating, cooling & ventilation
Ground-source (geothermal) heat pump
Also called: GSHP · ground source heat pump · geothermal heat pump · geothermal system · earth-energy system · geoexchange
A heat pump that exchanges heat with the ground through buried pipes or well water, giving steady efficiency even in deep cold.
What it means
Pipes buried in trenches or drilled boreholes (closed loop), or well water (open loop), carry heat between the ground and a heat pump inside the house. Because ground temperature is fairly stable year-round, efficiency stays high in winter and no defrost cycles are needed. The ground loop adds significant up-front cost compared with an air-source system.
Why it matters in an audit
DOE calls geothermal heat pumps among the most efficient heating and cooling options, and rebates for them are often larger to reflect their higher cost.
Typical numbers
Reference values with their sources. Your auditor’s report gives the figure for your own house.
| What | Value | Source |
|---|---|---|
| Heating efficiency, NRCan | About COP 3 in the coldest months for most systems | natural-resources.canada.ca ↗ |
In the United States
The 25D federal tax credit that covered geothermal heat pumps ended for systems installed after December 31, 2025.