Geothermal Heat Pumps

(Geoexchange or Ground-coupled Heat Pumps)

Geothermal heat pump systems tap the constant temperature of the earth to provide efficient heating and cooling. The systems operate by using water-source heat pumps which can be distributed throughout the building. Heat energy can be extracted from the earth in the winter, and added to the building. In the summer the process can be reversed. Unwanted heat is extracted from the building and added to the earth.

A geothermal heat pump ground-loop header as it enters the building

Basic Concept of a Geothermal Heat Pump System

• Geothermal pump systems couple the building's HVAC system to the earth.
• Geothermal heat pump systems eliminate the need for boilers, cooling towers etc.
• The ground provides a nearly constant temperature source of BTU's for efficient heating and serves as a sink for BTU's for efficient cooling.
• Geothermal pump systems are generally distributed systems rather than central systems.
• Energy can be efficiently recovered/ reused in buildings with simultaneous heating and cooling needs.

What are the Benefits of Geothermal Heat Pumps

Geothermal heat pump systems have several benefits, including:

• Low Operating Cost
• No Required Exposed Outdoor Equipment
• Level Seasonal Electric Demand
• No On-Site Combustion
• Long Life Expectancy
• Low Cost Integrated Water Heating
• Simplicity
• Low Maintenance
• No Supplemental Heat Required
• Low Environmental Impact

Vertical wells loop-field configuration

Who Can Benefit

While not a fit for all situations, geothermal pump systems are applicable in both existing and new buildings. In general, their benefits are greatest in buildings with similarly sized annual heating and cooling loads, and those desiring independent climate control of many rooms. The systems can provide efficient heating and cooling of different zones simultaneously. In New York State, installations have ranged from single family homes to hotels and 500,000-square-foot office buildings.

Office buildings and schools are particularly good applications for geothermal heat pumps. These facilities have relatively high occupancy, fluctuating usage schedules, and widely varying heating and cooling requirements within individual zones (offices and classrooms) that are difficult to meet efficiently with conventional systems. Further, efforts to improve the efficiency of conventional systems employ control strategies that can add considerable cost and complexity to the systems, increase maintenance requirements, and often compromise occupant comfort.

How the system works

Geothermal heat pumps transfer heat between the constant temperature of the earth and the building to maintain the building's interior space conditions. Below the surface of the earth throughout New York the temperature remains in the low 50 °F range throughout the year. This stable temperature provides a source for heat in the winter and a means to reject excess heat in the summer. With geothermal heat pump systems, water is circulated between the building and the "ground-loop" piping buried in the ground. In the summer, the water picks up heat from the building and moves it to the ground. In the winter the fluid picks up heat from the ground and moves it to the building. Heat pumps make the collection and transfer of this heat to and from the building possible.

Summer	Winter
In the summer, the earth acts as a cooling tower. The Heat Pump loads the loop with heat, sending warmed water to be cooled by the earth.	In the winter, the earth acts as the boiler. The Heat Pump extracts heat from the loop, sending cooled water to be warmed by the earth.

Geothermal pump systems exchange thermal energy between a building and the ground. When the building needs heating, the system extracts heat energy from the ground, and pumps it into the building where it is boosted by the heat pump to a comfortably warm temperature. Conversely, when the building needs cooling, the heat from the building is collected by the heat pumps and sent into the ground, much as a refrigerator's compressor transfers heat from inside the refrigerator to the outside. This exchange of thermal energy makes the system efficient. Rather than creating heat by burning a fuel on site, or chilled water by rejecting heat to the hot summer air, the geothermal heat pump system moves thermal energy between the ground and the building using heat pump technology.

Water is pumped to heat pumps around the building

The relatively constant temperature of the ground makes this energy transfer efficient through out the year - even during the coldest weather. When the building needs cooling the system takes advantage of the relatively constant ground temperature that is usually cooler than the outdoor air in the summer. Alternative systems must move energy from the building to the hotter outdoor air, while the geothermal heat pump system gains efficiency by transferring the energy to the cooler ground.

Geothermal Heat Pump System Manual

Download Manual in PDF Format

This document provides additional information about geothermal heat pump systems, how they work, when they should be considered and describes the steps involved in evaluating the cost effectiveness of a geothermal heat pump system. It describes the system and options and attempts to anticipate questions that building owners and designers might have about the technology. This document is designed to assist the layman in understanding the main concepts in geothermal heat pump systems while providing initial sources of information for the designer to pursue a specific project evaluation.

GEOTHERMAL HEAT PUMP CONTACTS

NYSERDA has attempted to collect contact information from all of the companies who provide geothermal heat pump studies as well as those who have experience with design and installation of ground loops and mechanical systems in New York State.  The firms provided here were assembled from a variety of sources. Reasonable efforts have been made to confirm the information. NYSERDA and the State of New York make no representations as to the accuracy or completeness of the information. Neither NYSERDA nor the State of New York: (1) endorse any of the firms listed; or (2) guarantee, warranty, or in any way represent or assume liability for any work proposed or carried out by their firms. Additionally, NYSERDA is not responsible for assuring that the design, engineering and construction of the project or geothermal heat pump system is proper or complies with any particular laws (including patent laws), regulations, codes, or industry standards. NYSERDA does not make any representations of any kind regarding the results to be achieved by the geothermal heat pump systems or the adequacy or safety of such measures.

RESIDENTIAL CONTACTS (32kb .xls) (16kb .PDF)

COMMERCIAL CONTACTS (61kb .xls) (19kb .PDF)

For more information please contact NYSERDA at (518) 862-1090 or 1-866-NYSERDA

New York City Department of Design and Construction

The New York City Department of Design and Construction (DDC) published a useful resource, the “Geothermal Heat Pump Manual,” which provides definitions, descriptions, and benefits of geothermal heat pumps. In addition the DDC’s manual discusses site evaluations, the process of choosing an appropriate ground source heat pump, and the performance and ratings of various systems. The DDC’s handbook contains a great deal of valuable information on the entire process of installing geothermal heat pumps and was created for project managers and consulting engineers that were working for the DDC.
http://home2.nyc.gov/html/ddc/downloads/pdf/geotherm.pdf

Commercial/Industrial Incentive Programs

Albany Molecular Research (Albany, NY) uses a groundwater cooling system as an alternative to traditional cooling towers

•  New Construction
•  Existing Facilities Program
•  New York Energy $mart^SM Loan Fund
•  FlexTech
•  Technical Assistance

Residential Incentive Program

Currently NYSERDA does not provide any specific incentives for Geothermal Heat Pumps in residential buildings. Incentives may be available for qualifying projects under the Residential Loan Fund. Other opportunities for residential customers to participate in NYSERDA programs are available at: Residential Incentives

Press Releases

Tannery Pond Community Center (Town of Johnsburg, NY) saves approximately $24,000 annually on its 11,200 square-foot facility

Case Studies

Albany Molecular Research, Inc.
Tannery Pond Community Center
Bard College
Indian River Central School District

Helpful Information Links

Geothermal Heat Pump Consortium

"The Geothermal Heat Pump Consortium works on increase the awareness and use of geoexchange technology throughout the United States and the world. The Geothermal Heat Pump Consortium acts as a resource for anyone wishing to know more about geoexchange technology. Its full time staff and industry allies can provide technical expertise, marketing research data and insight, and current industry activity status."

International Ground Source Heat Pump Association

"The mission of the International Ground Source Heat Pump Association and its membership is to promote the use of ground source heat pump technology worldwide through communication and education."

17 Columbia Circle, Albany, NY 12203-6399    Toll-Free: 1-866-NYSERDA or Local: 518-862-1090    Fax: 518-862-1091
New York City and Buffalo Regional Offices

© 2004 New York State Energy Research and Development Authority