The Italian geothermal pioneer, Prince Piero Ginori Conti showed geothermal heat could be used as an energy source. His work gave life to modern geothermal heat pumps.

Geothermal Heat Pumps

Geothermal heat pumps (sometimes referred to as GeoExchange, earth-coupled, ground-source, or water-source heat pumps) have been in use since the late 1940s. Geothermal heat pumps use the constant temperature of the earth as the exchange medium instead of the outside air temperature. This allows the system to reach fairly high efficiencies on the coldest of winter nights, nearly twice as much as air-source heat pumps on cool days.

While 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 to 75 degrees Fahrenheit. Like a cave, this ground temperature is warmer than the air above it during the winter and cooler than the air in the summer. Geothermal heat pumps takes advantage of this 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 a 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 are returned to you in energy savings in 5 to 10 years. System life is estimated at 25 years for the inside components and more than 50 years for the ground loop. There are approximately 40,000 geothermal heat pumps installed in the United States each year.

One has to wonder if Prince Conti ever thought his work would lead to such wide spread usage. With improvements to geothermal heat pumps over time, it certainly has.