A geothermal HVAC system uses the stable temperature of the earth to heat and cool buildings. It works by circulating fluid through a loop of underground pipes to exchange heat with the earth.

Unlike conventional furnaces that burn fuel to create heat, geothermal heat pumps transfer heat between the building and the ground. This makes them far more energy-efficient and environmentally friendly.

The four primary types are:

Horizontal loop
Vertical loop
Pond/lake loop
Open-loop system

Horizontal loops are ideal for new construction where ample land is available. They are less expensive to install than vertical systems but require more surface area.

Vertical loops involve drilling deep holes into the ground. They are used when land space is limited or when the soil is not suitable for horizontal trenching.

An open-loop system uses groundwater from a well or surface source as the heat exchange fluid. It discharges the water back into the ground after use, making it suitable only where groundwater is abundant and clean.

A closed-loop system circulates an antifreeze solution or water in a closed circuit of underground pipes. This fluid exchanges heat with the ground and never comes into direct contact with groundwater.

Geothermal systems can replace most types of furnaces, including:

Gas furnaces
Oil furnaces
Electric resistance heaters

They provide both heating and cooling in one system.

Geothermal systems can be 300–500% efficient, meaning they deliver 3 to 5 times more energy than they consume. Traditional systems average around 80–98% efficiency.

Lower energy bills Quiet operation Minimal maintenance Long lifespan (up to 50 years for loops, 20–25 years for heat pumps) Environmentally friendly, with lower greenhouse gas emissions.