GSHPs

Ground-source heat pumps (GSHPs) are heating and cooling systems that use the relatively constant temperature of the earth as a heat source and heat sink. They operate by circulating a fluid through a ground loop connected to a heat pump unit. In heating mode, heat is extracted from the ground and upgraded for indoor use; in cooling mode, heat is rejected to the ground.

Ground loops form the primary mechanism for exchanging heat with the earth. They can be closed-loop systems, with buried piping (horizontal trenches, vertical boreholes, or slinky configurations) containing a water–antifreeze solution, or open-loop systems that use groundwater through a heat exchanger. The choice depends on site conditions, water rights, and local regulations. The heat pump then transfers heat between the loop and the building’s air or hydronic system.

Performance is expressed through metrics such as coefficient of performance (COP) for heating and, in some contexts, seasonal COP (SCOP) or energy efficiency ratio (EER). GSHPs typically offer higher COPs than air-source heat pumps, particularly in cold climates, resulting in lower operating costs and reduced emissions when powered by clean electricity.

Applications span residential heating and cooling, hot water production, and commercial buildings. Advantages include high energy efficiency, quiet operation, long system life for the ground loop, and potential greenhouse gas emission reductions. Limitations involve higher upfront installation costs, the need for suitable land or groundwater access, and environmental or regulatory considerations related to drilling, groundwater protection, and permits. Proper design and professional installation are essential to realize the benefits of GSHPs.