Geothermal Heating and Cooling: Ground Source Heat Pumps

Apr 9, 2022DMA Engineering

What is a Heat Pump?

It’s essentially a refrigerator, and works off of the vapor-compression cycle.

A Little History on Geothermal and Heat Pumps

  • 1852—Lord Kelvin develops the theory for heat pumps.
  • 1940’s—Robert C. Webber installs first residential system after experimenting with a deep freezer.
    Professor Carl Nielsen of Ohio State University develops the first ground-source heat pump, for use at his residence.
    J.D. Krocker, an engineer in Portland, Oregon, pioneers the first commercial building-use of a groundwater heat pump.
  • 1970’s—People begin seriously looking for energy alternatives during the Oil Embargo.
    Dr. Jim Bose puts the math behind the technology to make it more readily usable in the U.S.
  • 1987—International Ground Source Heat Pump Association (IGSHPA) forms.

Ground source heat pumps are great heating systems with low-carbon emissions. They are popular due to their high efficiency and cheap operating costs. These characteristics make them well worth the investment. They also have the ability to reduce primary energy use and greenhouse gas emissions. Therefore, ground source heat pumps are gaining huge popularity.

A ground source heat pump is an environmentally friendly system used to heat various types of buildings. This heat pump produces no carbon emissions on site. It further uses the stored solar energy on the ground to produce heat and cooling results.

Ground Source Heat Pumps in Commercial Buildings

Ground source heat pumps are ideal for commercial buildings. They are best suited for those buildings that require abundant cooling in the summer and extra heating in the winter. However, expert configuration and installation are required for these systems. This is crucial for obtaining maximum efficiency. This also helps in attaining substantial energy savings along with low operating costs.

Geothermal heat pumps (GHPs), sometimes referred to as GeoExchange, earth-coupled, ground-source, or water-source heat pumps, have been in use since the late 1940s. They use the relatively constant temperature of the earth as the exchange medium instead of the outside air temperature.

Although many parts of the country experience seasonal temperature extremes — from scorching heat in the summer to sub-zero cold in the winter—a few feet below the earth’s surface the ground remains at a relatively constant temperature. Depending on latitude, ground temperatures range from 45°F (7°C) to 75°F (21°C). Like a cave, this ground temperature is warmer than the air above it during the winter and cooler than the air in the summer. The GHP takes advantage of these more favorable temperatures to become high efficient by exchanging heat with the earth through a ground heat exchanger.

As with any heat pump, geothermal and water-source heat pumps are able to heat, cool, and, if so equipped, supply the house with hot water. Some models of geothermal systems are available with two-speed compressors and variable fans for more comfort and energy savings. Relative to air-source heat pumps, they are quieter, last longer, need little maintenance, and do not depend on the temperature of the outside air.

A dual-source heat pump combines an air-source heat pump with a geothermal heat pump. These appliances combine the best of both systems. Dual-source heat pumps have higher efficiency ratings than air-source units, but are not as efficient as geothermal units. The main advantage of dual-source systems is that they cost much less to install than a single geothermal unit, and work almost as well.

Even though the installation price of a geothermal system can be several times that of an air-source system of the same heating and cooling capacity, the additional costs may be returned in energy savings in 5 to 10 years, depending on the cost of energy and available incentives in your area. System life is estimated at up to 24 years for the inside components and 50+ years for the ground loop. There are approximately 50,000 geothermal heat pumps installed in the United States each year. For more information, visit the International Ground Source Heat Pump Association