DOE/EE-0291

Internet: www.eere.energy.gov/femp/

No portion of this publication may be altered in any form without

prior written consent from the U.S. Department of Energy, Energy

Efficiency and Renewable Energy, and the authoring national laboratory.

Geothermal heat pump

surface water loops.

Geothermal Heat Pumps Deliver Big Savings

for Federal Facilities

An update on geothermal heat pump technologies and the Super ESPC

Energy-efficiency improvements at federal facilities must enhance support for the agency’s

critical missions while also saving energy and money. Geothermal heat pumps (GHPs, also

known as ground-source heat pumps or GeoExchange systems) can do both, and can help

meet energy-conservation, emissions-reduction, and renewable-energy goals.

GHP technology is now well known as a proven, reliable, efficient, and

cost-effective choice for space heating, cooling, and water heating in federal facilities. Federal facilities have invested more than $200 million in

GHPs since 1993.

GHPs achieve high energy efficiency by using a geothermal resource

(the ground, groundwater, or surface water) instead of ambient air as a

heat source and heat sink. The temperature of this resource is generally

cooler than ambient air in the summer and warmer than ambient air

during the coldest months, so GHPs operate over a smaller temperature

lift—and therefore more efficiently—throughout the year.

Although the industry is growing quickly, many federal energy and facility

managers are still unfamiliar with GHP technology. The Federal Energy

Management Program (FEMP) offers technical and financing assistance

to make GHPs just as easy to implement in federal facilities as the more conventional, less

efficient alternatives (see textbox on following page).

Advantages of GHPs

Proven Efficiency and Energy Savings

Replacing conventional heating and air conditioning systems with GHPs typically saves

15–25 percent of total building energy use in nonresidential buildings; in residential buildings savings can be as high as 40 percent. GHPs reduce peak load as well. An evaluation of

a 4000-home comprehensive GHP retrofit at the U.S. Army’s Fort Polk in Louisiana showed

that the GHPs reduced summer peak electric demand on the post by 7.5 MW, or 43 percent,

and reduced electricity consumption in post housing by 33 percent, while eliminating natural

gas consumption altogether (Hughes and Shonder 1998).

GHPs can also contribute to meeting emissions reduction goals because they use less electricity than conventional equipment to provide the same amount of cooling and heating.

Leading by example,

saving energy and

taxpayer dollars

in federal facilities
Improved Comfort—Better

Humidity Control, Zone-Level

Temperature Control, Quiet

Operation, Reliability

Besides their intrinsic efficiency,

GHPs offer other benefits that are

highly valued at federal facilities.

At several U.S. military installations, GHP retrofits have cut the

energy use of family housing units

by about 30 percent, and is also

seen as an investment in the troops’

morale and quality of life. Residents

are more comfortable in their homes

because the new GHPs operate reliably and quietly and provide better

humidity control.

Nonresidential buildings can benefit from GHPs as well. Typically,

each zone is provided with its own

unit, which can be controlled separately to maintain occupant comfort.

Lower Maintenance Costs

The low cost of maintaining GHPs

contributes significantly to their

cost-effectiveness. The technology

is simpler and inherently less prone

to malfunction, requires less maintenance, and has a longer service

life than air-source heat pumps.

GHPs have no outdoor equipment

to be tampered with, filled with

leaves or other debris, or buffeted

by the weather.

GHPs are generally charged with

refrigerant and sealed at the factory—

a feature that reduces required labor

for installation and maintenance and

benefits the environment as well.

Spills of refrigerant are eliminated

and overall costs are lower because

installers don’t have to handle refrigerants during installation and leaks

are extremely rare. GHPs typically

use 25 percent less refrigerant than

other air-conditioning equipment.

An analysis of 1996–1998 maintenance records for the Lincoln,

Nebraska, school district shows

that annual corrective maintenance

(repair) costs for four GHP-equipped

schools averaged 2.1 cents/ft2, compared to 2.9 to 6.1 cents/ft2

 for

conventional systems in 16 other

schools. Another analysis by the

Geothermal Heat Pump Consortium

found average total (preventive and

corrective) maintenance costs for

25 GHP-equipped buildings to be

Financing through GHP Super ESPCs or UESCs

Federal agencies can use energy savings performance contracts (ESPCs) to finance their energy projects, allowing them to

reduce their energy use and costs without depending on congressional appropriations to fund the improvements. Using

FEMP’s Super ESPCs, agencies can partner with prequalified, competitively selected energy service companies (ESCOs)

and use an expeditied contracting process to implement their projects quickly.

Federal facilities worldwide can use a Technology-Specific GHP Super ESPC, which offers financing and private-sector

expertise specifically geared to GHP projects. Energy utility companies have also been strong proponents of GHPs, and

many offer financing and services to federal agencies through utility energy service contracts (UESCs).

FEMP Project Facilitators

Using a FEMP Project Facilitator is your best insurance for achieving a successful energy project with persistent savings.

Agencies that use FEMP project facilitators benefit from having an expert consultant on contractual, financial, and technical

issues, and an experienced guide through the entire process of developing, implementing, and verifying savings from an

energy project. FEMP project facilitation services for Super ESPC projects are free through the initial proposal stage and

reimbursable thereafter.

Unbiased, Authoritative Technical Assistance from FEMP’s GHP Core Team

The FEMP GHP Core Team provides agencies with the most authoritative technical assistance on GHPs available anywhere. FEMP project facilitators supported by specialists from the core team have the practical engineering design and

construction experience to ensure that the job is done right. Some of the technical information and resources offered by the

core team are available at www.ornl.gov/femp/. The FEMP GHP Core Team lead is John Shonder, (865) 574-2015,

shonderja@ornl.gov.

For More Information, Visit FEMP’s Web Site

To learn about ESPCs and UESCs, go to www.eere.energy.gov/femp/financing.

For contact information for the FEMP representatives in a DOE Regional Office near you, who will help you get started and

get assistance from FEMP Services, go to www.eere.energy.gov/femp/financing/espc/getting_started.html.

2 — FEDERAL ENERGY MANAGEMENT PROGRAM
about 11 cents/ft2

—16 to 30 cents/

ft2 less than for conventional systems. Both studies are published

by ASHRAE (Cane et al. 1998;

Shonder et al. 2000).

GHP Efficiency Saves

Energy and Money

GHPs save energy and money

because they operate more efficiently than conventional equipment. A compressor operates much

more efficiently in a water-source

heat pump than in an air-source

unit. In addition, air needs to be

circulated on only one side of the

GHP, and less power is needed to

move the water (or anti-freeze mixture) on the other side than would

be needed to move air.

The temperature of the geothermal

source/sink is far more stable than

outdoor air, with much less severe

highs and lows. Unlike air-source

units, GHP systems do not use

extra energy to power defrost cycles.

In most locations there is no need

for backup electric resistance heat.

Common-loop GHPs recover heat

as part of their design. In cooler

weather, the heat pumps serving

the building perimeter extract heat

from the common loop to provide

space heating, while units serving

core areas are cooling space and

rejecting heat to the common loop.

Under many operating conditions,

the common loop is in balance, no

net heat exchange with the ground

is required, and the offset between

heating and cooling units reduces

the thermal load on the ground

heat exchanger.

Recovered heat in GHP systems is also

used to heat water. Desuperheaters

are commonly installed with GHPs

in military family housing to transfer heat from the heat pump into the

water heaters. Dedicated water-towater units are also found in many

larger GHP systems.

Application and Feasibility

of GHP Technology for

Federal Sites

GHP System Types

GHPs are adaptable to almost any

type of building and can be configured to fit a wide variety of sites and

circumstances. Designing GHP

systems to optimize efficiency

and cost-effectiveness depends on

choosing the configuration most

effective and economical for the

application. GHP systems are not

feasible in every case, but their

intrinsic efficiency and the wide

range of design options makes

them the most cost-effective choice

for many situations.

The common denominator among

all GHP systems is that they move

heat between the geothermal source/

sink and a building via water-source

heat pumps to provide space heating and cooling, water heating, or

refrigeration. A GHP system may

have one or many water-source

heat pumps, depending on the

application. For example, in military family housing, each residence

might be served by one heat pump

with its own vertical-bore ground

heat exchanger. Larger, nonresidential facilities might have many heat

pumps on a common loop with a

central variable-speed pumping

station and one large geothermal

GHPs were determined to be the most cost-effective option available to replace the old, source/sink.

ineffective HVAC system in Marston Pavilion, a historic building and community center for

a U.S. Marine Corps base. The new GHP system costs 60 percent less to operate than

the old system and provides excellent air quality and thermal comfort for the building.

FEDERAL ENERGY MANAGEMENT PROGRAM — 3
Hybrid systems use a combination of

geothermal resources and ambient air

as heat sources/sinks, and are often

the most economical approach where

cooling needs are significantly larger

than heating needs.

Important Factors in

Determining Feasibility

Detailed estimates of costs and

savings are required to determine

the feasibility of any given project.

However, there are some guidelines

that can be used to screen potential

projects before deciding whether to

proceed with a feasibility study.

Building Function. In general, the

most promising applications for

GHP retrofits are buildings that

are maintained at reasonably comfortable temperature setpoints (68–

78°F) for at least 40 hours per week.

Equipment to be Replaced. It is

not usually economically feasible

to replace highly efficient, recently

purchased equipment. There is more

potential for savings when GHPs

replace older, less efficient equipment that is more than about ten

years old.

Energy Costs. In general, higher

energy costs tend to improve the

economics of GHP retrofit projects,

but this is not always the case. For

example, in a climate with significant heating requirements and high

electricity rates, it may be more

economical to heat with natural

gas, regardless of the efficiency of

the GHP.

The economics of any GHP project

can be improved by utilizing the

waste heat generated during the

cooling cycle. For buildings with

high water heating loads (e.g., residences, hotels, laundry facilities),

GHPs can provide hot water at

essentially no cost during the cooling season. Project economics are

also improved if other energy conservation measures with relatively

short paybacks are included with

the installation of GHPs.

Maintenance Costs. GHPs generally cost less to maintain than

conventional heating and cooling

equipment, and this savings can

sometimes mean the difference

between a feasible project and an

unfeasible one.

Retrofit Strategy. As with any retrofit measure, the capital cost is

reduced if portions of the existing

system (e.g., ductwork) can be used

in the GHP system.

Local Water and Well Regulations.

The installation of the groundcoupling system may be subject to

local codes and regulations governing wells, water, and protection of

water quality. Regulations affecting

open-loop systems are common

and variable, some requiring reinjection wells rather than surface

drainage, for example. Some states

require permits to use even private

ponds as geothermal resources.

Geothermal Resources

and GHP Systems

The type of geothermal resource

that is available near the building is

a primary determinant of the type

of GHP system that will be most

economical at any particular site.

Ground heat exchangers (or

ground loops). Heat exchange with

the ground using vertical or horizontal loops may be an economical

option if there is enough land area

GHP retrofits in military family housing are valued for their energy and cost savings and for

improving the quality of life for the troops and their families.

4 — FEDERAL ENERGY MANAGEMENT PROGRAM
near the building to accommodate

ground heat exchangers. Horizontal

loops require considerably more

land area than vertical-bore heat

exchangers, but may be less expensive to install, depending on the

types of soil and rock formations

encountered in drilling.

Ground heat exchangers are an

option almost anywhere and are

by far the majority among currently

operating GHPs. However, as the

industry matures and experience

in the field grows, GHPs using surface water or groundwater for heat

exchange are slowly gaining prominence. These other geothermal

options may be even more economical than ground-coupled

systems and should be considered

where they exist.

Groundwater already being

pumped. Some federal sites pump

groundwater to the surface, treat it,

The wide range of design options makes GHPs the most cost-effective choice for many

applications.

and reinject it as a part of groundwater remediation projects. Tapping

into groundwater that is already

being pumped to the surface could be

an extremely economical approach.

Typically a plate-and-frame type

heat exchanger is used to transfer

heat between the groundwater and

a common loop serving water-source

heat pumps in nearby buildings. In

years after the remediation project is

completed, pumping on the groundwater side of the heat exchanger

can be reoptimized for the HVAC

application and continued using the

same supply and reinjection wells.

Stationary surface water. Where

large volumes of stationary surface

water are near buildings, they may

be economical resources for heat

exchange. A common loop to serve

water-source heat pumps in a nearby

building can be submerged directly

into a surface water impoundment

such as a reservoir, runoff retention

basin, reflecting pool, pond, or lake.

If the water is used for recreational

or other purposes that might interfere with this approach, an on-shore

pump house with a heat exchanger

and protected intake from and discharge to the body of water could

be considered.

Moving surface water. A large river

with reliable flow and modest current could be an economical heat

exchange resource for nearby buildings. An on-shore pumphouse with

a heat exchanger and protected

intake from and discharge to the

river might be advisable. Issues such

FEDERAL ENERGY MANAGEMENT PROGRAM — 5
as historical high and low water conditions, debris flow, and commercial and recreational traffic would

be serious considerations.

Wastewater streams. Large-volume,

reliable, flowing wastewater streams

can be used to condition a heat

exchanger. Maintenance of the heat

exchanger and the stability of the

missions of the facilities that are

the source of the wastewater would

be considerations.

Groundwater. Groundwater may

be an economical heat exchange

resource if large quantities are

available at a reasonable depth,

along with an acceptable and economical means of disposal. Poor

water quality might require the use

of expensive heat exchanger materials, and in some formations additional maintenance and aquifer

reinjection might be expensive.

Standing-column well. Standingcolumn-well GHP systems are

similar to standard groundwater

GHPs, but because water is recirculated between the well and the building, only one well may be required

(larger projects may have several

wells in parallel). Standing-column

wells are feasible in areas with nearsurface bedrock. Deep bores are

drilled, creating a long-standing

column of water from the static

water level down to the bottom of

the bore. Water is recirculated from

one end of the column to the other.

To reduce required bore length, the

system can be designed to bleed

part of the water rather than reinjecting it all during peak heat rejection or extraction periods, causing

water inflow to the column from

the surrounding formation to cool

or heat the column as needed.

References

Cane, E., A. Morrison, and C. J. Ireland, 1998. “Maintenance and Service Costs of Commercial Building

Ground-Source Heat Pump Systems,” ASHRAE Transactions, 104, pt. 2, 1998.

Hughes, P. J., and J. A. Shonder, 1998. “The Evaluation of a 4000-Home Geothermal Heat Pump Retrofit

at Fort Polk, Louisiana: Final Report,” ORNL/CON-460, Oak Ridge National Laboratory, 1998. (Available

at www.ornl.gov/femp)

Shonder, J. A., M. A. Martin, P. J. Hughes, and J. Thornton, 2000. “Geothermal Heat Pumps in K-12 Schools: A

Case Study of the Lincoln, Nebraska, Schools,” ORNL/TM-2000/80, Oak Ridge National Laboratory, April 2000.

(Available at www.ornl.gov/femp)

GHP and ESPC Information and Resources

DOE Geothermal Energy: www.eere.energy.gov/geothermal

FEMP GHP Technology-Specific Super ESPCs: www.eere.energy.gov/femp/financing/espc/technologies.html

FEMP GHP Resources: www.eere.energy.gov/femp/financing/espc/ghpresources.html

FEMP GHP Core Team: www.ornl.gov/femp

Geothermal Heat Pump Consortium: www.geoexchange.org

International Ground Source Heat Pump Association: www.igshpa.okstate.edu

6 — FEDERAL ENERGY MANAGEMENT PROGRAM
Federal Energy Management Program

The federal government is the largest energy consumer in the nation. Annually, the total primary energy consumed by the federal

government is 1.4 quadrillion British thermal units (quads), costing $9.6 billion. This represents 1.4% of the primary energy consumption in

the United States. The Federal Energy Management Program was established in 1974 to provide direction, guidance, and assistance to federal

agencies in planning and implementing energy management programs that will improve the energy efficiency and fuel flexibility of the

federal infrastructure.

Over the years, several federal laws and Executive Orders have shaped FEMP’s mission. These include the Energy Policy and Conservation

Act of 1975; the National Energy Conservation and Policy Act of 1978; the Federal Energy Management Improvement Act of 1988; the

National Energy Policy Act of 1992; Executive Order 13123, signed in 1999; and most recently, Executive Order 13221, signed in 2001, and

the Presidential Directive of May 3, 2001.

FEMP is currently involved in a wide range of energy-assessment activities, including conducting new technology demonstrations, to hasten

the penetration of energy-efficient technologies into the federal marketplace.

About FEMP’s New Technology Demonstrations

The Energy Policy Act of 1992 and subsequent Executive Orders mandate that

energy consumption in federal buildings

be reduced by 35% from 1985 levels by

the year 2010. To achieve this goal, the

U.S. Department of Energy’s Federal

Energy Management Program (FEMP)

sponsors a series of activities to reduce

energy consumption at federal installations nationwide. FEMP uses new technology demonstrations to accelerate the

introduction of energy-efficient and

renewable technologies into the federal

sector and to improve the rate of technology transfer.

As part of this effort, FEMP sponsors

the following series of publications that

are designed to disseminate information

on new and emerging technologies:

Technology Focuses—brief information

on new,energy-efficient, environmentally

friendly technologies of potential interest to the federal sector.

Federal Technology Alerts—longer

summary reports that provide details on

energy-efficient, water-conserving, and

renewable-energy technologies that have

been selected for further study for possible

implementation in the federal sector.

Technology Installation Reviews—concise

reports describing a new technology and

providing case study results, typically

from another demonstration program or

pilot project.

Other Publications—we also issue other

publicationsonenergy-saving technologies

with potential use in the federal sector.

FEDERAL ENERGY MANAGEMENT PROGRAM — 7
Produced for the U.S. Department

of Energy, Energy Efficiency

and Renewable Energy, by the

Oak Ridge National Laboratory

DOE/EE-0291

April 2004

For More Information

EERE Information Center

1-877-EERE-INF or

1-877-337-3463

www.eere.energy.gov/femp

General Program Contacts

Ted Collins

New Technology Demonstration

Program Manager

Federal Energy Management Program

U.S. Department of Energy

1000 Independence Ave., SW EE-92

Washington, D.C. 20585

Phone: (202) 586-8017

Fax: (202) 586-3000

theodore.collins@ee.doe.gov

Steven A. Parker

Pacific Northwest National Laboratory

P.O. Box 999, MSIN: K5-08

Richland, WA 99352

Phone: (509) 375-6366

Fax: (509) 375-3614

steven.parker@pnl.gov

Technology-Specific

GHP Super ESPC

Tatiana Strajnic

ESPC Program Lead

Federal Energy Management Program

Phone: (202) 586-9230

Fax: (202) 586-3000

tatiana.strajnic@ee.doe.gov

Doug Culbreth

FEMP National GHP Program

Representative

DOE Atlanta Regional Office

Phone: (919) 870-0051

Fax: (919) 870-0052

carson.culbreth@ee.doe.gov

Technical Contact and Author

John Shonder

FEMP GHP Core Team Lead

Oak Ridge National Laboratory

Phone: (865) 574-2015

Fax: (865) 574-9338

shonderja@ornl.gov

Disclaimer

This report was sponsored by the United States Department of Energy, Energy Efficiency and

Renewable Energy, Federal Energy Management Program. Neither the United States Government nor any agency or contractor thereof, nor any of their employees, makes any warranty,

express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents

that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not

necessarily constitute or imply its endorsement, recommendation, or favoring by the United

States Government or any agency or contractor thereof. The views and opinions of authors

expressed herein do not necessarily state or reflect those of the United States Government or

any agency or contractor thereof.

A Strong Energy Portfolio for a Strong America

Energy efficiency and clean, renewable energy will mean a stronger economy, a cleaner

environment, and greater energy independence for America. Working with a wide array

of state, community, industry, and university partners, the U.S. Department of Energy’s

Office of Energy Efficiency and Renewable Energy invests in a diverse portfolio of

energy technologies.