Ground source heat systems, sometimes refered to as geothermal exchange systems, use heat pumps to capture the stable temperatures of the earth in order to pre-heat and pre-cool a building, reducing the strain on conventional comfort systems. Notably, this is a different strategy than geothermal power, which is a direct energy source typically found in areas of the world near tectonic plate boundaries.
+ Highly efficient
+ Cost-effective and durable relative to other heating and cooling systems
+ Can reduce heating & cooling costs up to 75% compared to conventional systems
+ Low maintenance
+ Low or zero emissions
+ Quiet operation
CHALLENGES AND OPPORTUNITIES
+ Not practical for all sites
+ Open systems do present risks due to unknown geological conditions
+ High initial costs, specifically related to drilling and site exploration
+ Federal tax credits incentives exist (through 12/31/16) to offset installation costs
+ Special financing is available from Energy Star®, among other organizations
Using a ground source heat approach requires a heat pump, a heat exchange component, and a delivery system; this can be in the form radiant surfaces (water-to-water) or forced air (water-to-air). The heat exchange component uses two thermally conductive materials – a source and a sink – to transfer energy, heat, or cooling.
Water-to-water systems use water as a thermal conduit to deliver comfort throughout the building. Examples include: radiant cooling panels, radiant under-floor heating, baseboard radiators, and conventional cast iron radiators. Water-to-water systems are the most efficient for of thermal exchange and are preferred for pool heating and domestic hot water pre-heating.
Water-to-air systems are slightly less efficient than water to water, due to the energy loss between conductors. Water-to-air systems are often used to replace forced air furnaces and central air conditioning systems. Variable designs allow for split systems, high-velocity and ductless systems.
Washington Square Park House
New York, NY
2,000 square feet
Historic Front Street
New York, NY
150,000 square feet
NYC Geothermal Heat Pump Manual [PDF]
NYC Department of Design & Construction