City of Alexandria, VA
Page updated Jul 27, 2012 9:34 AM
Incorporating Ground-Source Heat Pumps in Historic Buildings
One of the greatest difficulties for homeowners restoring historic buildings is creating a modern, livable space without sacrificing the building’s original character and design. Ground-source heat pumps solve the historic preservation challenges surrounding landscape design and interior space, as ground-source heating systems are primarily underground and unobtrusive. Specifically historic buildings are poised to greatly benefit from installing ground-source heat pumps as they run quietly, require little maintenance, and don’t require the same equipment eyesores as traditional systems.
As detailed in our article on ground-source heat pumps, ground-source heat systems are categorized as either open- or closed-loop systems. Factors such as climate, total energy demand, and available space determine which geothermal system to implement for maximum energy savings. Geothermal technology remains a favorite among architects, engineers, and property owners for its flexibility in design and ease of adaptation.
Considering the small lot size for the average residential historic building, geothermal heat pumps possess a clear advantage over other heating and cooling systems since vertical loops require minimal footprints. Standing column wells, a hybrid design of an open- and a closed-loop vertical system, drilled near the building create a column of water which allows for vertical water flow and heat exchange. A pump placed in each standing column well draws water up from the well's typical depth of 1,500 feet and transports the water via an underground piping loop to the building's heat pump located inside. The system then re-injects the water into the top of the well where it exchanges heat with the surrounding bedrock during its return to the well bottom.
According to the U.S. Department of Energy, geothermal heating systems can recoup all associated costs in 5-10 years. Since underground equipment, such as piping, typically carries 50-year guarantees and indoor parts generally last 25 years, a geothermal system can ultimately provide substantial cash flow through operating and maintenance savings. In order to maximize the cost benefits of a ground-source heating system, particularly in historic buildings, homeowners should prioritize the repair and installation of insulation for doors, windows, walls, ceilings, and floors before setting up a ground-source heat pump.
For further information, visit http://www.geothermalgenius.org for detailed benefits on geothermal systems, a savings calculator, financing options, and resources to find a local installer. Before installing geothermal wells in both historic and non-historic areas, you must first obtain a permit from the Virginia Department of Health (VDH). For information on private well regulations, and to download an application form online, visit VDH’s website.