Geothermal Heating and Cooling Explained

By Industry Resource Desk

Geothermal heating and cooling, also called ground-source heat pump technology, uses the relatively stable temperature of the earth a few feet below the surface to condition indoor space throughout the year. Unlike a conventional furnace or rooftop air conditioner that fights outdoor air temperature swings, a ground-source system exchanges heat with soil, rock, or water that stays far more consistent across seasons. This makes it one of the more discussed alternatives for commercial buildings looking to reduce reliance on combustion equipment and stabilize year-round comfort, though it is not a universal fit for every site.

The terms "geothermal heating and cooling" and "ground-source heat pump" describe the same underlying technology in most commercial and residential contexts. Large-scale power-generating geothermal plants are a different application entirely; the systems discussed here are heat pumps that move heat rather than generate electricity.

How Geothermal Heating and Cooling Works

A ground-source heat pump does not create heat the way a furnace does. Instead, it transfers heat between the building and the ground using a refrigeration cycle, similar in principle to the compressor-based cycle found in refrigeration and standard air conditioning equipment.

In heating mode, fluid circulating through underground piping absorbs warmth from the surrounding earth and carries it to the heat pump, which concentrates that heat and delivers it into the building's distribution system. In cooling mode, the process reverses: heat collected from the building's indoor air is carried through the loop and released into the ground. Because the ground is used as a heat source in winter and a heat sink in summer, the same equipment handles both seasons without needing separate heating and cooling plants.

Core Equipment: Inside and Underground

A commercial geothermal installation generally has three interconnected parts:

• The heat pump unit or units, typically located indoors or in a mechanical room, which handle the refrigerant cycle and connect to the building's air handling or hydronic distribution system.
• The ground loop, a network of buried or submerged piping filled with water or a water-antifreeze blend that carries heat to and from the earth.
• The distribution system, which moves conditioned air or water through ductwork, fan coils, radiant systems, or variable refrigerant piping to occupied spaces.

For larger commercial buildings, this is often not a single heat pump but a distributed arrangement of smaller units serving different zones, tied back to a shared loop field.

Ground Loop Configurations

The configuration of the underground loop is largely dictated by available land, soil and rock conditions, and access to water.

Horizontal Loops

Pipe is laid in trenches a few feet below grade across a wide area. This approach generally requires more open land, making it more common on suburban or rural sites with room to spare.

Vertical Loops

Boreholes are drilled straight down, sometimes several hundred feet, with piping inserted and the hole backfilled. Vertical loops need far less surface area, which is why they are frequently used on constrained urban lots, under parking areas, or on campuses where horizontal trenching is not practical.

Pond or Lake Loops

Coiled piping is submerged in an adjacent body of water rather than buried in soil. This can reduce drilling costs where a suitable water body already exists on or near the property, though water depth and volume must be sufficient for reliable heat exchange.

Open-Loop Systems

Groundwater is drawn from a well, passed through the heat pump for heat exchange, and then returned to the aquifer or another discharge point. Open-loop systems depend on local water rights, water quality, and regulatory approval, and they introduce ongoing water-quality monitoring that closed-loop systems do not require.

Can Geothermal Work in Cold Climates?

Ground temperature several feet below the surface stays markedly more stable than air temperature, which is why ground-source systems can continue providing heat even during extended cold spells that would strain an air-source heat pump's capacity. Performance in cold climates depends on correct loop sizing, soil and rock characteristics, and the heating load of the building, so a system designed for one property cannot be assumed to perform identically on another.

Site Feasibility for Commercial Properties

Feasibility hinges on several site-specific factors: available land or drilling access, subsurface geology, groundwater conditions, existing utility and structural constraints, and the building's actual heating and cooling load profile. Dense urban sites, for example, may only have room for vertical boreholes under a parking lot or building footprint, while campus properties might combine multiple loop fields tied to a shared distribution network.

Subsurface conditions vary widely even within a single region. Areas with thin soil over bedrock, for instance, may hit rock sooner during drilling, which affects both design and the drilling process itself. A preliminary geotechnical and hydrogeological assessment is typically necessary before committing to a loop configuration.

Scaling Up: Campus and Networked Geothermal

Geothermal is not limited to single buildings. Networked or "thermal energy network" approaches connect multiple buildings, a campus, or even a city block to a shared loop field or ambient piping network, allowing buildings with different heating and cooling needs to balance load across the system. This model is gaining attention for districts, universities, and mixed-use developments where individual building footprints are too small for standalone loop fields but combined land or right-of-way access supports a shared system.

Geothermal in Restaurants and Grocery Facilities

Restaurants and grocery operations generate significant waste heat from refrigeration compressors and cooking equipment. In some designs, that reject heat can be captured and integrated with a building's heat-recovery strategy, reducing the heating load a geothermal system otherwise needs to meet, or supplementing domestic hot-water needs. Coordinating geothermal HVAC with refrigeration heat rejection requires close collaboration between HVAC and refrigeration contractors during design, since the two systems are not automatically compatible without proper controls integration.

Maintenance and Long-Term Considerations

Ground loops themselves generally have long service lives and limited exposure to weather, but the mechanical components, heat pumps, pumps, and controls still require routine inspection, filter changes, and periodic performance checks like any HVAC equipment. Open-loop systems carry additional responsibility for water-quality testing and well maintenance to prevent scaling or fouling. Facility teams should also plan for loop-field mapping and records retention, since underground piping is far more difficult to service or troubleshoot without accurate documentation.

A Commercial Decision Framework

Before committing to a geothermal project, a facility team benefits from a phased evaluation: a load study of existing heating and cooling demand, a geotechnical assessment of the site, a review of permitting and water-rights requirements where applicable, and a comparison of loop configurations against available land or drilling access. Phased retrofits, where geothermal supplements rather than fully replaces existing HVAC equipment, can reduce disruption to tenants and operations while the technology's performance on that specific site is confirmed.

Takeaway

Geothermal heating and cooling offers a way to stabilize year-round comfort using the earth's relatively constant temperature, but its practicality depends heavily on site-specific conditions: available land, subsurface geology, water access, and the building's own load profile. For commercial and multi-tenant properties, a careful feasibility study and phased integration plan matter more than any general claim about efficiency or savings.

This article is general industry information published as an educational resource. It is not advice about any specific project, and it does not reflect a recommendation or opinion of the business hosting this page. Talk to a qualified professional about your own situation.