What is geothermal?
Geothermal Energy is heat (thermal) derived from the earth (geo). It is the thermal energy contained in the rock and fluid (that fills the fractures and pores within the rock) in the earth's crust.


Geothermal heat pumps
Geothermal heat pumps use the stable temperatures of the ground (often vertical boreholes typically are 100 to 400 feet deep) as a heat source to warm buildings in winters and as a heat sink to cool them in summer. A heat pump works through application of the "refrigeration cycle." Also called ground-source heat pumps or Geoexchange units. Select an image below to enlarge.

How does geothermal work?
You already have a heat pump in your home -- your refrigerator. If you put your hand behind it, you'll feel the heat that has been pumped from the inside and from its contents. It's the same principle that the geothermal heat pump uses to move heat to and from the home and earth.

In the summer, the heat pump extracts heat from the conditioned space and sends it out to the earth loop to warm the relatively cool ground, or pond, if it's an aqua loop.

In the winter, this process is reversed. The heat pump extracts heat from the relatively warm ground, usually warmer than the outdoor cold air, and pumps this heat into the conditioned space.

The result is the need for far less energy than the conventional air source heat pump system for year-round conditioning. Even in the winter, it is more efficient than conventional natural gas or oil heating systems.


Benefits of geothermal
Geothermal heat pump systems have lower operating costs, lower maintenance costs, lower life cycle costs, increased reliability, and greater comfort than alternative cooling and heating systems. In this section we will discuss their many advantages.

In most cases, experience indicates that the geothermal heat pump will be the choice with the lowest overall costs throughout the life of the system; in other words, the lowest life cycle costs. In many cases, it will be the system with the lowest cost to buy and install, i.e., the lowest first cost.

Since it can be installed in a portion of an equipment room or small closet, it gives owners more usable space. Heat pumps offer a high degree of design flexibility since they come in a variety of sizes and configurations. In retrofit situations, they can replace rooftop equipment or a central chiller and boiler. If building occupancy or zone loads change, additional equipment or larger heat pumps can be added.


Advantages of geothermal
In both commercial and residential installations, geothermal heat pump systems typically have lower maintenance costs than conventional systems as all equipment is installed inside the building or underground. This means that there is no outside equipment exposed to weather and vandalism. All refrigerant systems are sealed, similar to household refrigerators.

Geothermal systems are very flexible. They can be easily and inexpensively subdivided or expanded to fit building remodeling or additions. They are particularly well-suited to "tenant finish" installations.

In commercial installations, systems can save money by recovering excess heat from building interior zones and moving it to the perimeter of the building. They can also save money by allowing management to isolate and shut down unoccupied areas of the building.

Refrigerant Loop geothermal systems have several advantages over other geothermal systems. They are potentially more efficient than water loop systems. They require fewer feet of buried piping than other geothermal systems, have no freeze problems, and better heat transfer