Renewable HVAC

According the the Department of Energy, geothermal heat pumps (GHPs), sometimes referred to as GeoExchange, earth-coupled, ground-source, or water-source heat pumps, have been in use since the late 1940s. They use the constant temperature of the earth as the exchange medium instead of the outside air temperature

​​Geothermal Heating & Cooling (GHC) systems convert stored thermal energy in the earth to heating and cooling for homes and businesses. The systems require use of drilled wells, piping loops, and efficient heat pumps to transfer heat between the wells and a home or business.

  • In the winter, the GHC system pulls heat from the earth into the house or building;
  • In the summer, the system removes heat from the house or building by dumping it into the ground; and
  • Year-round, they can heat water with a desuperheater, a secondary heat exchanger, that transfers heat from the earth in the winter, and from your home in the summer, into your domestic hot water tank.

GHC systems are the most energy-efficient, environmentally clean, and cost-effective space conditioning systems available, according to the Environmental Protection Agency.1 EPA found that

GHC systems can reduce energy consumption by over 40% compared to air source heat pumps, and by over 70% compared to electric resistance heating with standard air-conditioning equipment. EPA also found that GHC systems are 48% more efficient than the best gas furnaces on a source fuel basis, and over 75% more efficient than oil furnaces.​

More information on types of geothermal heat pumps can be found here: Energy Saver

​Prince George’s County Geothermal Renewable Energy Credits (RECs)

In 2012, Maryland became the first state in the country to make the energy generated by GHC technologies eligible for the Renewable Portfolio Standard (RPS) as a Tier 1 renewable source (HB 1186). GHC system owners are also eligible for Prince George’s County Geothermal Renewable Energy Credits (RECs), equivalent to 1 MegaWatt-hour (MWh) of electricity.

To qualify for RECs, the GHC technologies must:

  • Meet ENERGY STAR standards (see Geothermal Heat Pumps Key Product Criteria website for more information),
  • Displace electric or non-natural gas (NG) fossil fuel heating systems
    • 29% of homes in the Mid-Atlantic region use electric/non-NG fossil fuel heating
    • 46% of businesses in the Mid-Atlantic region use electric/non-NG fossil fuel heating
  • Displace old and presumed inefficient air conditioning systems
    • 44% of homes in the Mid-Atlantic region have AC units 10 years+ old
    • 74% of businesses in the Mid-Atlantic region have AC units 10+ years old

Take the following steps to register your GHC system with the Maryland Public Service Commission and capture an additional revenue stream:

  • Register for Prince George’s County Geothermal Renewable Energy Credits
    • Fill out the Geothermal Renewable Energy Facility Application posted on the Public Service Commission website as an Excel spreadsheet. Detailed instructions for registering your RECs are located on the first tab of the geothermal application.
      • For residential systems, the PSC will use the Climate Master Savings Calculator to estimate the quantity of RECs associated with your system.
      • For commercial systems, you’ll need to enter the projected MWh’s from your installer’s engineering studies onto the Prince George’s County Geothermal Renewable Energy Credit application spreadsheet
    • Send the completed spreadsheet to
    • Print, sign and file with the Commission a signed/verified original application and affidavit, along with 17 copies of the Application and supporting documents to:
      • David J. Collins
        Executive Secretary
        Maryland Public Service Commission
        6 Saint Paul St.
        Baltimore, MD 21202
  • Sell your Prince George’s County Geothermal Renewable Energy Credits
    • Information about selling Prince George’s County Geothermal Renewable Energy Credits can be found here, which includes information that includes:

Sustainability Frameworks

GHC can be a major contributor to goals set by established “green building” standards such as the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED), Net Zero Energy Homes and Buildings, and the Living Building Challenge.

One elementary school in Richardville, Kentucky leveraged green design with solar PV and GHC to become the nation’s first Net Zero Energy School, which means that the school generates more energy than it consumes over the course of a year.

Geothermal Heating & Cooling Collage

Apply for a Geothermal Heat Pump Grant

Questions? Contact:

Clean Energy Program Manager Marta Tomic via email at or telephone 410-260-2608.