The Department of Defense has long been the largest consumer of energy within the U.S. government. To rectify this, Congress has mandated that 25% of the Department’s energy consumption come from renewable sources by 2025. The Department of Defense has specific goals for each of its facilities to help it achieve this goal.

At Fort Lee, in Virginia, a boom in new construction will incorporate energy efficiency improvements to help the facility reduce its carbon footprint. Various renewable energy technologies have also been considered, including solar and wind. Recently, the Army announced that it is incorporating geothermal heating and cooling systems into two barracks buildings currently under construction at Fort Lee. Both structures are expected to be completed in 2012.

image via U.S. Army

Fundamentally, the systems will circulate water through a closed-loop system from the buildings to an underground geothermal well. In the summer, heat from inside the building will be absorbed underground, and returned to the building to cool it. In the winter, the process is reversed, heating the building with warm water from under the ground. ”We’re just taking advantage of the temperature difference between the water and the earth to transfer heat or cold air to the building,” said Gary Ogden, chief of operations, Directorate of Public Works and Logistics.

The U.S. Department of Energy estimates that these types of systems generally consume 20-25 percent less electricity than conventional heating and cooling systems. Additionally, they are about 40% more efficient in the winter than regular heat pumps. Due to the cost of installation, geothermal systems are typically only cost-effective on new construction, such as the barracks at Fort Lee. Ogden also stressed the importance of energy conservation. ”There have been estimates that we can reduce our energy by 10-15% if we could just get people to modify their behavior,” he said.