Outdoor air temperatures fluctuate throughout the year with the changing seasons. In contrast, ground temperatures about four to six feet below the earth's surface remain relatively moderate and constant all year. A geothermal system circulates an environmentally friendly water-based solution through a buried closed loop system to use the ground as a heat source or a heat sink, depending on the season. Geothermal heat pump systems are sometimes called "ground source", "earth-coupled" or "ground exchange" technology.
Geothermal equipment has the ability to heat and cool buildings, while providing domestic hot water at the same time. Like a refrigerator or air conditioner, these systems use a heat pump to force the transfer of heat from or into the ground. Geothermal systems can save 30% to 70% on monthly utility bills and operate solely on electricity. In contrast, a traditional air-source heat pump transfers heat to- and from the outside air and requires more energy, especially during temperature extremes. Geothermal systems have many benefits, including more usable building space due to a smaller footprint, cost savings due to less maintenance and improved exterior aesthetics from no cooling tower outside of a building.
In August 2010, Salisbury University completed its first geothermal project, Manokin Hall. During project planning for the residence hall, a geothermal solution was evaluated and compared to a high efficiency traditional alternative. The geothermal system was bid with a net savings of approximately $100,000 over the traditional approach due to competitive bidding and a consumer-favorable market. Nanticoke and Wicomico halls also have been renovated with geothermal systems.
The Manokin geothermal project also provided an unexpected educational opportunity. In 2009, Salisbury University renovated Pocomoke Hall and planners kept its relatively new heating and cooling system. While Pocomoke Hall cools with a high efficiency HVAC, heating and hot water are provided by duel fuel - heating oil or natural gas-fired equipment. Since Pocomoke is the mirror image of Manokin and used in the same way, conditions were ideal for an experiment. The savings rate will vary through the year, based on average ambient temperatures and it will be exciting to learn more about the benefits of geothermal systems.