FEDERAL ENERGY MANAGEMENT PROGRAM DOE/EE-0245

Ground-Source Heat Pumps Applied to Federal Facilities–Second Edition Technology for reducing heating and air-conditioning costs

The ground-source technology can and exterior to the facility, are typically less provide an energy-efficient, cost-effective way to than those for conventional systems. heat and cool Federal facilities. A ground-source heat pump is a unique means of using the thermo- Potential Application dynamic properties of earth and groundwater for The technology has been shown to be techni- efficient operation throughout the year in virtu- cally valid and economically attractive in many ally any climate. This Federal Technology Alert, applications. It is efficient and effective. This Federal one of a series on new technologies, describes the Federal Technology Alert reports on the collec- theory of operation, energy-savings mechanisms, tive experience of heat pump users and evalua- Technology range of applications, and field experience for the tors and provides application guidance. ground-source heat pump technology. Alert An estimated 400,000 ground-source heat pumps Energy Savings Mechanism are operating in the private and public sector, although most of these systems operate in resi- A publication series A ground-source heat pump system (shown dential applications. A ground-source heat designed to speed the below) uses the ground or groundwater as a heat pump system can be applied in virtually any adoption of energy- source during winter operation and as a heat category of climate or building. The large num- sink for summer cooling. The stability of subsur- efficient and renewable ber of installations testifies to the stability of face temperatures results in year-round energy technologies in the this technology. The reported problems can efficiency. In general, users have reported satis- Federal sector usually be attributed to faulty design or faction with the operation and energy costs installation of the ground-coupling system— savings of the technology, and maintenance emphasizing the importance of good design, costs are reduced. Moreover, water-loop-based Prepared by the documentation, installation and system ground-source heat pumps use less commissioning. New Technology than conventional air-source heat pumps or air- Demonstration conditioning systems, and the factory-sealed sys- Although local site conditions may dictate the type Program tems reduce the potential for leaking refrigerant. of system employed, the high first cost and its Space requirements for equipment, both interior effect on the overall life-cycle cost are typically

No portion of this publi- cation may be altered in any form without prior written consent from the U.S. Department of Energy and the authoring national laboratory. Typical ground-source heat pump system applied to a commercial facility

Internet: http://www.eren.doe.gov/femp FEDERAL ENERGY MANAGEMENT PROGRAM

the constraining factors. Installation • in areas where is unavail- Implementation Barriers costs vary depending on the design and able or where the cost is higher than The major barriers to rapid implementa- application, but typically range between electricity. tion of this technology involve awareness $1,500 and $3,000/ton ($425 and $840/ The following cautions are recommended and acceptance by users and HVAC kW). Ground-source heat pumps have for any ground-source heat pump appli- designers (which is growing rapidly) the potential to reduce cooling energy cation under consideration: and higher initial implementation costs by 30 to 50% and reduce heating en- than other options. In addition, there is a ergy by 20 to 40%. • install as a complete system, with the system and each unit properly limited infrastructure and availability of Ground-source heat pumps tend to be designed and sized skilled and experienced designers and more cost-effective than conventional installers of ground-source heat pump • use only experienced and certified systems in the following applications: systems. Several Federal facilities that installers have ground-source heat pump systems • in new construction where the tech- • analyze soil type and thermal are listed in this Federal Technology Alert. nology is relatively easy to incorpo- conductivity, if appropriate The reader is invited to ask questions and rate, or to replace an existing system • be aware that local water and well learn more about the technology. at the end of its useful life regulations may restrict some system • in climates characterized by high types daily temperature swings, or where • obtain equipment and installation winters are cold or summers hot, and warranties. where electricity cost is higher than average

Disclaimer This report was sponsored by the United States Department of Energy, Office of Federal Energy Management Programs. 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 informa- tion, 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, mark, 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. FEDERAL ENERGY MANAGEMENT PROGRAM

Ground-Source Heat Pumps Applied to Federal Facilities–Second Edition Technology for reducing heating and air-conditioning costs

than conventional air-source heat pumps or air-conditioning systems, with the exception of direct-expansion-type ground- source heat pump systems. Installation costs are relatively high but are made up through Federal low maintenance and operat- ing expenses and efficient energy Technology use. The greatest barrier to effec- Alert tive use is improper design and installation; employment of well- trained, experienced, and respon- sible designers and installers is Ground-source heat pump of critical importance. This Federal Technology Alert Abstract provides the detailed information and proce- dures that a Federal energy manager needs to Ground-source heat pumps can provide an evaluate most ground-source heat pump appli- energy-efficient, cost-effective way to heat and cations. The New Technology Demonstration cool Federal facilities. Through the use of a Program (NTDP) selection process and general ground-coupling system, a conventional water- benefits to the Federal sector are outlined. source heat pump design is transformed to a Ground-source heat pump operation, system unique means of utilizing thermodynamic prop- types, design variations, energy savings, and erties of earth and groundwater for efficient other benefits are explained. Guidelines are pro- operation throughout the year in most climates. vided for appropriate application and installa- In essence, the ground (or groundwater) serves tion. Two case studies are presented to give the as a heat source during winter operation and a reader a sense of the actual costs and energy heat sink for summer cooling. Many varieties savings. Current manufacturers, technology in design are available, so the technology can be users, and references for further reading are in- adapted to almost any site. Ground-source heat cluded for prospective users who have specific or pump systems can be used widely in Federal highly technical questions not fully addressed in applications and, with proper installation, offer this Federal Technology Alert. Sample case great potential for the Federal sector, where spreadsheets are provided in Appendix A. increased efficiency and reduced heating and Additional appendixes provide other infor- cooling costs are important. Ground-source mation on the ground-source heat pump heat pump systems require less refrigerant technology.

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Contents

Abstract ...... 1 Background ...... 4 Introduction to Ground-Source Heat Pumps ...... 4 About the Technology ...... 5 Application Domain Energy-Saving Mechanism Other Benefits Ground-Coupled System Types Variables Affecting Design and Performance Variations System Design and Installation Federal Sector Potential ...... 14 Technology Screening Process Estimated Savings and Market Potential Laboratory Perspective Application ...... 15 Application Screening Where to Apply Ground-Source Heat Pumps What to Avoid Design and Equipment Integration Equipment Warranties Energy Codes and Standards Utility Incentives and Support Technology Performance ...... 18 Field Experience Energy Savings Maintenance Installation Costs Other Impacts Case Studies ...... 21 Example 1: Upstate New York Facility Example 2: Oklahoma City Facility The Technology in Perspective ...... 26 The Technology’s Development Technology Outlook Manufacturers ...... 27 Who is Using the Technology ...... 27 For Further Information ...... 28 Appendix A: Sample Case Spreadsheet Models ...... 33 Appendix B: Federal Life-Cycle Costing Procedures and the BLCC Software ...... 40 Appendix C: Performance and Efficiency Terminology Defined ...... 41 Appendix D: Ground-Source Heat Pump Manufacturers ...... 43 Appendix E: ARI Rating Conditions ...... 44

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Background This Federal Technology Alert updates the original ground-source heat pump Federal Technology Alert published in 1995. As with the previous document, the focus of this material is on commer- cial application of ground-source heat pumps (GSHPs) in the Federal sector. While GSHPs are well established in the residential sector, their application in the Federal sector is lagging, in part because of a lack of experience with the technol- ogy by those in decision-making posi- tions. This Federal Technology Alert provides the information and proce- dures that Federal energy managers need to evaluate the potential for ground-source heat pump application at their facilities. The focus of this report is on the New Technology Demonstra- Figure 1. Typical ground-source heat pump system applied to a commercial facility. tion Program (NTDP) selection process, and general benefits to the Federal sec- accurately the specific application; water loop circulates to all the water- tor are outlined. Ground-source heat however, most are the result of market- source heat pumps connected to the sys- pump operation, system types, design ing efforts and the need to associate (or tem. The (for winter operation) variations, energy-savings, and other disassociate) the heat pump systems and the (for summer benefits are explained. Guidelines are from other systems. This Federal Tech- operation) provide a fairly constant provided for appropriate application nology Alert refers to them as ground- water-loop temperature, which allows and installation. Two case studies are source heat pumps except when it is the water-source heat pumps to operate presented to give the reader a sense of necessary to distinguish a specific de- at high efficiency. the actual costs and energy savings sign or application of the technology. potential of the technology. Current A conventional air-source heat pump A typical ground-source heat pump uses the outdoor ambient air as a heat manufacturers, technology users, system design applied to a commercial source during the winter heating opera- and references for further reading are facility is illustrated in Figure 1. included for prospective users who tion and as a heat sink during the sum- have specific or highly technical ques- It is important to remember that the mer cooling operation. Air-source heat tions not fully addressed in this Federal primary equipment used for ground- pumps are subject to higher tempera- Technology Alert. Sample case spread- source heat pumps are water-source ture fluctuations of the heat source sheets are provided in Appendix A. heat pumps. What makes a ground- and heat sink. They become much less Several other appendixes provide addi- source heat pump different (unique, effective—and less efficient—at extreme tional information pertinent to ground- efficient, and usually more expensive to ambient air temperatures. This is par- source heat pumps. install) is the ground-coupling system. ticularly true at low temperatures. In In addition, most manufacturers have addition, using air as a Introduction to Ground- developed extended-range water- transfer medium is not as effective as Source Heat Pumps source heat pumps for use as ground- water systems because of air’s lower source heat pumps. . Ground-source heat pumps are known by a variety of names: geoexchange heat A conventionally designed water-source A ground-source heat pump uses the pumps, ground-coupled heat pumps, heat pump system would incorporate a ground (or in some cases groundwater) geothermal heat pumps, earth-coupled boiler as a heat source during the winter as the heat source during the winter heat pumps, ground-source systems, heating operation and a cooling tower to heating operation and as the heat sink groundwater source heat pumps, well reject heat (heat sink) during the sum- during the summer cooling operation. water heat pumps, heat mer cooling operation. This system type Ground-source heat pumps may be sub- pumps, and a few other variations. is also sometimes called a boiler/tower ject to higher temperature fluctuations Some names are used to describe more water-loop heat pump system. The than conventional water-source heat

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pumps but not as high as air-source heat Although ground source heat pumps (5,825 kW) are connected to a ground- pumps. Consequently, most manufac- are used throughout the United States, coupled loop consisting of 400 wells, turers have developed extended-range the majority of new ground-source heat each 425 feet (129 m) deep (Gahran systems. The extended-range systems pump installations in the United States September 1993). operate more efficiently while subject to are in the southern and mid-western Public schools are another good applica- the extended-temperature range of the states (from North Dakota to Florida). tion for the ground-source heat pump water loop. Like water-source heat Oklahoma, Texas, and the East Coast technology with over 400 installations pumps, ground-source heat pumps use have been particularly active with new nationwide. In 1995, the Lincoln, a water loop between the heat pumps ground-source heat pump installations. Nebraska, Public School District built and the heat source/heat sink (the Environmental concerns, particularly four new 70,000 square foot elementary earth). The primary exception is the from the potential for groundwater con- schools. Space conditioning loads are direct-expansion ground-source heat tamination with a leaking ground loop, met by 54 ground-source heat pumps pump, which is described in more detail and a general lack of understanding of ranging in size from 1.4 to 15 tons, with later in this Federal Technology Alert. the technology by HVAC companies a total cooling capacity of 204 tons. and installers have limited installations Ground-source heat pumps take advan- Gas-fired provided hot water in the West (Lund and Boyd 2000). tage of the thermodynamic properties of for pre-heating of the outside air and Usually the technology does well in the earth and groundwater. Tempera- for terminal re-heating. Compared with an area where it has been actively tures below the ground surface do not other similar new schools, these four promoted by a local utility or the fluctuate significantly through the day geothermally conditioned facilities manufacturer. or the year as do ambient air tempera- used approximately 26% less source tures. Ground temperatures a few feet Ground-source heat pumps are not a energy per square foot of floor area below the surface stay relatively con- new idea. Patents on the technology (Shonder et al. 1999). stant throughout the year. For this rea- date back to 1912 in Switzerland Multiple unitary systems are not the son, ground-source heat pumps remain (Calm 1987). One of the oldest ground- only arrangement suitable for large extremely efficient throughout the year source heat pump systems, in the commercial applications. It is also in virtually any climate. United Illuminating headquarters possible to design large centralized building in New Haven, Connecticut, heat-pump system consisting of recipro- About the Technology has been operating since the 1930s cating and centrifugal (Pratsch 1990). Although ground-source (up to 19.5 million Btu/h) and to use Application Domain heat pump systems are probably better these systems to support central-air- In 1999, an estimated 400,000 ground- established today in rural and suburban handling units, variable air-volume source heat pumps were operating in residential areas because of the land area systems, or distributive two-pipe residential and commercial applica- available for the ground loop, the mar- coil units. tions, up from 100,000 in 1990. In 1985, ket has expanded to urban and commer- it was estimated that only around 14,000 cial applications. Energy-Saving Mechanism ground-source heat pump systems were The vast majority of ground-source installed in the United States. Annual Heat normally flows from a warmer me- heat pump installations utilize unitary sales of approximately 45,000 units were dium to a colder one. This basic physical equipment consisting of multiple water- reported in 1997. With a projected annual law can’t be reversed without the addi- source heat pumps connected to a growth rate of 10%, 120,000 new units tion of energy. A heat pump is a device common ground-coupled loop. Most would be installed in 2010, for a total that does so by essentially “pumping” individual units range from 1 to 10 tons of 1.5 million units in 2010 (Lund and heat up the temperature scale, then (3.5 to 35.2 kW), but some equipment is Boyd 2000). transferring it from a cold material to a available in sizes up to 50 tons (176 kW). warmer one by adding energy, usually In Europe, the estimated total number of Large-tonnage commercial systems in the form of electricity. A heat pump installed ground-source heat pumps at are achieved by using several unitary functions by using a refrigerant cycle the end of 1998 was 100,000 to 120,000 water-source heat pumps, each respon- similar to the household refrigerator. In (Rybach and Sanner 2000). sible for an individual control zone. the heating mode, a heat pump removes Nearly 10,000 ground-source heat pumps One of the largest commercial ground- the heat from a low temperature source, have been installed in U.S. Federal build- source heat pump systems operating such as the ground or air, and supplies ings, over 400 schools and thousands of today is at Stockton College in Pomona, that heat to a higher temperature sink, low-income houses and apartments New Jersey, where 63 ground-source such as the heated interior of a building. (ORNL/SERDP, no date). heat pumps totaling 1,655 tons

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In the cooling mode, the process is pumps, although electrically driven, are although research continues directed reversed and the heat is extracted from classified as a renewable-energy tech- toward verifying this claim. It is clear, the cooler inside air and rejected to the nology. The justification for this classifi- however, that ground-source heat warmer outdoor air or other heat sink. cation is that the ground acts as an pumps eliminate the exterior fin-coil For space conditioning of buildings, effective collector of solar energy. The condensers of air-cooled heat pumps that remove heat from out- renewable-energy classification can systems and eliminate the need for cool- door air in the heating mode and reject it affect Federal goals and potential ing towers and their associated mainte- to outdoor air in the cooling mode are funding opportunities. nance and chemical requirements. This common. These are normally called is a primary benefit cited by facilities in An environmental benefit is that air-source or air-to-air heat pumps. Air- highly corrosive areas such as near the ground-source heat pumps typically use source heat pumps have the disadvan- ocean, where salt spray can significantly 25% less refrigerant than split-system tage that the greatest requirement for reduce outdoor equipment life. air-source heat pumps or air- building heating or cooling is necessar- conditioning systems. Ground-source Ground-source heat pump technology ily coincident with the times when the heat pumps generally do not require offers further benefits: less need for outdoor air is least effective as a heat tampering with the refrigerant during supplemental resistance heaters, no source or sink. Below about 37ºF, installation. Systems are generally exterior coil freezing (requiring defrost supplemental heating is required to sealed at the factory, reducing the cycles) such as that associated with air- meet the heating load. For this reason, potential for leaking refrigerant in the source heat pumps, improved comfort air-source heat pumps are essentially field during assembly. during the heating season (compared unfeasible in cold climates with outdoor with air-source heat pumps, the supply temperatures below 37ºF for extended Ground-source heat pumps also require air temperature does not drop when re- periods of time. less space than conventional heating covering from the defrost cycle), signifi- and cooling systems. While the require- The efficiency of any heat pump is in- cantly reduced fire hazard over that ments for the indoor unit are about the versely proportional to the temperature associated with fossil fuel-fired systems, same as conventional systems, the difference between the conditioned reduced space requirements and haz- exterior system (the ground coil) is space and the heat source (heating ards by eliminating fossil-fuel storage, underground, and there are no space mode) or heat sink (cooling mode) as and reduced local emissions from those requirements for cooling towers or can be easily shown by a simple thermo- associated with other fossil fuel-fired air-cooled condensers. In addition, the dynamic analysis (Reynolds and heating systems. ground-coupling system does not neces- Perkins 1977). For this reason, air-source sarily limit future use of the land area Another benefit is quieter operation, heat pumps are less efficient and have a over the ground loop, with the because ground-source heat pumps lower heating capacity in the heating exception of siting a building. Interior have no outside air fans. Finally, mode at low outdoor air temperatures. space requirements are also reduced. ground-source heat pumps are reliable Conversely, air-source heat pumps are There are no floor space requirements and long-lived, because the heat pumps also less efficient and have a lower cool- for boilers or , just the unitary are generally installed in climate- ing capacity in the cooling mode at high systems and circulation pumps. controlled environments and therefore outdoor air temperatures. Ground- Furthermore, many distributed ground- are not subject to the stresses of extreme source heat pumps, however, are not source heat pump systems are designed temperatures. Because of the materials impacted directly by outdoor air tem- to fit in ceiling plenums, reducing the and joining techniques, the ground- peratures. Ground-source heat pumps floor space requirement of central coupling systems are also typically reli- use the ground, groundwater, or surface mechanical rooms. able and long-lived. For these reasons, water, which are more thermally stable ground-source heat pumps are expected and not subjected to large annual Compared with air-source heat pumps to have a longer life and require less swings of temperature, as a heat source that use outdoor air coils, ground-source maintenance than alternative (more or sink. heat pumps do not require defrost conventional) technologies. cycles or crankcase heaters and there is Other benefits virtually no concern for coil freezing. Ground-Coupled System Types The primary benefit of ground-source Cooling tower systems require electric The ground-coupling systems used in heat pumps is the increase in operating resistance heaters to prevent freezing in ground-source heat pumps fall under efficiency, which translates to reduced the tower basin, also not necessary with three main categories: closed-loop, heating and cooling costs, but there are ground-source heat pumps. open-loop and direct-expansion. The additional advantages. One notable It is generally accepted that mainte- type of ground coupling employed will benefit is that ground-source heat nance requirements are also reduced,

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loop is filled with a heat transfer fluid, typically water or a water-(b) solution, although other heat transfer fluids may be used.(c) When cooling re- quirements cause the closed-loop liquid temperature to rise, heat is transferred to the cooler earth. Conversely, when heating requirements cause the closed- loop fluid temperature to drop, heat is absorbed from the warmer earth. Closed-loop systems use pumps to cir- culate the heat transfer fluid between the heat pump and the ground loop. Because the loops are closed and sealed, the heat pump is not subject to mineral buildup and there is no direct interaction (mixing) with groundwater. There are several varieties of closed- loop configurations including horizon- tal, spiral, vertical, and submerged. Horizontal loops. Horizontal loops, illustrated in Figure 2a, are often consid- ered when adequate land surface is available. The pipes are placed in trenches, typically at a depth of 4 to 10 feet (1.2 to 3.0 m). Depending on the specific design, from one to six pipes may be installed in each trench. Al- though requiring more linear feet of pipe, multiple-pipe configurations con- serve land space, require less trenching, and therefore frequently cost less to install than single-pipe configurations. Trench lengths can range from 100 to 400 feet per system cooling ton (8.7 to Figure 2. Ground-coupling system types. 34.6 m/kW), depending on soil charac- teristics and moisture content, and the affect heat pump system performance function of specific geography, available number of pipes in the trench. Trenches (therefore the heat pump energy con- land area, and life-cycle cost economics. are usually spaced from 6 to 12 feet (1.8 sumption), auxiliary pumping energy to 3.7 m) apart. Closed-loop systems. Closed-loop requirements, and installation costs. systems consist of an underground These systems are common in residen- Choice of the most appropriate type of network of sealed, high-strength plastic tial applications but are not frequently ground coupling for a site is usually a pipe(a) acting as a heat exchanger. The applied to large-tonnage commercial

(a) Acceptable piping includes high quality or polybutylene. PVC is not acceptable in either heat transfer characteristics or strength. (b) Common heat transfer fluids include water or water mixed with an antifreeze: sodium chloride, calcium chloride, potassium carbonate, potassium acetate, , propylene gycol, methyl alcohol, or ethyl alcohol. (c) Note that various heat transfer fluids have different densities and thermodynamic properties. Therefore, the heat transfer fluid selected will affect the required pumping power and the amount of heat transfer pipe. Furthermore, some local regulations may limit the selection and use of certain antifreeze solutions.

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applications because of the significant generally 6 inches (15.2 cm) wide; the • Advantages: Requires less total pipe land area required for adequate loops stand vertically in the narrow length than most closed-loop de- transfer. The horizontal-loop systems trenches. In cases where trenching is a signs; requires the least pumping can be buried beneath lawns, landscap- large component of the overall installa- energy of closed-loop systems; ing, and parking lots. Horizontal tion costs, spiral-loop systems are a requires least amount of surface systems tend to be more popular where means of reducing the installation cost. ground area; ground temperature there is ample land area with a high As noted with horizontal systems, typically not subject to seasonal water table. slinky systems are also generally variation. associated with lower-tonnage systems • Advantages: Trenching costs typi- • Disadvantage: Requires drilling where land area requirements are not a cally lower than well-drilling costs; equipment; drilling costs frequently limiting factor. flexible installation options. higher than horizontal trenching • Advantages: Requires less ground costs; some potential for long-term • Disadvantages: Large ground area area and less trenching than other heat buildup underground with required; ground temperature subject horizontal loop designs; installation inadequately spaced bore holes. to seasonal variance at shallow costs sometimes less than other depths; thermal properties of soil Submerged loops. If a moderately sized horizontal loop designs. fluctuate with season, rainfall, and pond or lake is available, the closed-loop burial depth; soil dryness must be • Disadvantages: Requires more total piping system can be submerged, as il- properly accounted for in designing pipe length than other ground- lustrated in Figure 2d. Some companies the required pipe length, especially in coupled designs; relatively large have installed ponds on facility grounds sandy soils and on hilltops that may ground area required; ground tem- to act as ground-coupled systems; dry out during the summer; pipe perature subject to seasonal variance; ponds also serve to improve facility system could be damaged during larger pumping energy requirements aesthetics. Submerged-loop applica- backfill process; longer pipe lengths than other horizontal loops defined tions require some special consider- are required than for vertical wells; above; backfilling the trench can be ations, and it is best to discuss these antifreeze solution viscosity increases difficult with certain soil types and directly with an engineer experienced in pumping energy, decreases the heat the pipe system could be damaged the design applications. This type of sys- transfer rate, and thus reduces during backfill process. tem requires adequate surface area and overall efficiency; lower system depth to function adequately in re- Vertical loops. Vertical loops, illustrated efficiencies. sponse to heating or cooling require- in Figure 2c, are generally considered ments under local weather conditions. Spiral loops. A variation on the multiple when land surface is limited. Wells are In general, the submerged piping pipe horizontal-loop configuration is the bored to depths that typically range system is installed in loops attached to spiral loop, commonly referred to as the from 75 to 300 feet (22.9 to 91.4 m) deep. concrete anchors. Typical installations “slinky.” The spiral loop, illustrated in The closed-loop pipes are inserted into require around 300 feet of heat transfer Figure 2b, consists of pipe unrolled in the vertical well. Typical piping require- piping per system cooling ton circular loops in trenches; the horizontal ments range from 200 to 600 feet per (26.0 m/kW) and around 3,000 square configuration is shown. system cooling ton (17.4 to 52.2 m/kW), feet of pond surface area per ton depending on soil and temperature con- Another variation of the spiral-loop (79.2 m2/kW) with a recommended ditions. Multiple wells are typically system involves placing the loops minimum one-half acre total surface required with well spacing not less than upright in narrow vertical trenches. area. The concrete anchors act to secure 15 feet (4.6 m) in the northern climates The spiral-loop configuration generally the piping, restricting movement, but and not less than 20 feet (6.1 m) in south- requires more piping, typically 500 to also hold the piping 9 to 18 inches (22.9 ern climates to achieve the total heat 1,000 feet per system cooling ton to 45.7 cm) above the pond floor, allow- transfer requirements. A 300- to 500-ton- (43.3 to 86.6 m/kW) but less total trench- ing for good convective flow of water capacity system can be installed on one ing than the multiple horizontal-loop around the heat transfer surface area. acre of land, depending on soil condi- systems described above. For the hori- It is also recommended that the heat- tions and ground temperature. zontal spiral-loop layout, trenches are transfer loops be at least 6 to 8 feet (1.8 to generally 3 to 6 feet (0.9 to 1.8 m) wide; There are three basic types of vertical- 2.4 m) below the pond surface, prefer- multiple trenches are typically spaced system heat exchangers: U-tube, ably deeper. This maintains adequate about 12 feet (3.7 m) apart. For the divided-tube, and concentric-tube thermal mass even in times of extended vertical spiral-loop layout, trenches are (pipe-in-pipe) system configurations. drought or other low-water conditions.

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Rivers are typically not used because water must either be re-injected into the pump to achieve sufficient temperature they are subject to drought and flood- ground by separate wells or discharged differences in the heat transfer chain ing, both of which may damage the to a surface system such as a river or (refrigerant to fluid to earth). Each also system. lake. Local codes and regulations requires a pump to circulate water be- may affect the feasibility of open-loop tween the heat pump and the ground- • Advantages: Can require the least systems. couple. Direct-expansion systems, total pipe length of closed-loop illustrated in Figure 2h, remove the need designs; can be less expensive than Depending on the well configuration, for an intermediate heat transfer fluid, other closed-loop designs if body of open-loop systems can have the highest the fluid-refrigerant heat exchanger, and water available. pumping load requirements of any of the circulation pump. Copper coils are the ground-coupled configurations. In • Disadvantage: Requires a large body installed underground for a direct ideal conditions, however, an open-loop of water and may restrict lake use exchange of heat between refrigerant application can be the most economical (i.e., boat anchors). and earth. The result is improved heat type of ground-coupling system. transfer characteristics and thermody- Open-Loop Systems. Open-loop sys- • Advantages: Simple design; lower namic performance. tems use local groundwater or surface drilling requirements than closed- water (i.e., lakes) as a direct heat transfer The coils can be buried either in deep loop designs; subject to better ther- medium instead of the heat transfer vertical trenches or wide horizontal modynamic performance than fluid described for the closed-loop excavations. Vertical trenches typically closed-loop systems because well(s) systems. These systems are sometimes require from 100 to 150 square feet of are used to deliver groundwater at referred to specifically as “groundwater- land surface area per system cooling ton ground temperature rather than as a source heat pumps” to distinguish them (2.6 to 4.0 m2/kW) and are typically 9 to heat exchanger delivering heat trans- from other ground-source heat pumps. 12 feet (2.7 to 3.7 m) deep. Horizontal in- fer fluid at temperatures other than Open-loop systems consist primarily of stallations typically require from 450 to ground temperature; typically lowest extraction wells, extraction and reinjec- 550 square feet of land area per system cost; can be combined with potable tion wells, or surface water systems. cooling ton (11.9 to 14.5 m2/kW) and are water supply well; low operating These three types are illustrated in typically 5 to 10 feet (1.5 to 3.0 m) deep. cost if water already pumped for Figures 2e, 2f, and 2g, respectively. Vertical trenching is not recommended other purposes, such as irrigation. in sandy, clay or dry soils because of the A variation on the extraction well • Disadvantages: Subject to various poor heat transfer. system is the standing column well. local, state, and Federal clean water This system reinjects the majority of the Because the ground coil is metal, it is and surface water codes and regula- return water back into the source well, subject to corrosion (the pH level of the tions; large water flow requirements; minimizing the need for a reinjection soil should be between 5.5 and 10, al- water availability may be limited or well and the amount of surface though this is normally not a problem). not always available; heat pump heat discharge water. If the ground is subject to stray electric exchanger subject to suspended mat- currents and/or galvanic action, a There are several special factors to con- ter, corrosive agents, scaling, and bac- cathodic protection system may be sider in open-loop systems. One major terial contents; typically subject to required. Because the ground is subject factor is water quality. In open-loop highest pumping power require- to larger temperature extremes from the systems, the primary heat exchanger ments; pumping energy may be direct-expansion system, there are addi- between the refrigerant and the ground- excessive if the pump is oversized or tional design considerations. In winter water is subject to , corrosion, poorly controlled; may require well heating operation, the lower ground coil and blockage. A second major factor is permits or be restricted for extraction; temperature may cause the ground the adequacy of available water. The water disposal can limit or preclude moisture to freeze. Expansion of the ice required flow rate through the primary some installations; high cost if buildup may cause the ground to heat exchanger between the refrigerant reinjection well required. buckle. Also, because of the freezing and the groundwater is typically Direct-Expansion Systems. Each of the potential, the ground coil should not be between 1.5 and 3.0 gallons per minute ground-coupling systems described located near water lines. In the summer per system cooling ton (0.027 and above uses an intermediate heat transfer cooling operation, the higher coil tem- 0.054 L/s-kW). This can add up to a fluid to transfer heat between the earth peratures may drive moisture from the significant amount of water and can be and the refrigerant. Use of an intermedi- soil. Low moisture content will change affected by local water resource regula- ate heat transfer fluid necessitates a soil heat transfer characteristics. tions. A third major factor is what to do higher compression ratio in the heat with the discharge stream. The ground-

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Only one U.S. manufacturer currently Annual air temperatures, moisture amplitudes of annual surface ground offers direct-expansion ground-source content, soil type, and ground cover all temperature swings. Figure 4, though heat pump systems. Systems are avail- have an impact on underground soil illustrating a specific location, illustrates able from 24,000 to 60,000 Btu/h (heat- temperature. In addition, underground how the annual soil temperature varies ing/cooling capacity) (7.0 to 17.6 kW). temperature varies annually as a func- with depth, soil type, and season. For Larger commercial applications tion of the ambient surface air tempera- vertical ground loop systems, the mean require multiple units with individual ture swing, soil type, depth, and time annual earth temperature (Figure 3a) is ground coils. lag. Figure 3 contains a map of the an important factor in the ground loop United States indicating mean annual design. With horizontal ground loop • Advantages: Higher system effi- underground soil temperatures and systems, the ground surface annual ciency; no circulation pump required. • Disadvantages: Large trenching re- quirements for effective heat transfer area; ground around the coil subject to freezing (may cause surface ground to buckle and can freeze nearby water pipes); copper coil should not be buried near large trees where root system may damage the coil; oil return can be complicated, particularly for vertical heat exchanger coils or when used for both heating and cooling; leaks can be catastrophic; higher skilled instal- lation required; installation costs typically higher; this system type re- quires more refrigerant than most other systems; smaller infrastructure in the industry.

Variables Affecting Design and Performance Among the variables that have a major impact on the sizing and effectiveness of a ground-coupling system, the impor- tance of underground soil temperatures and soil type deserves special mention. Underground Soil Temperature. The soil temperature is of major importance in the design and operation of a ground- source heat pump. In an open-loop system, the temperature of ground- water entering the heat pump has a direct impact on the efficiency of the system. In a closed-loop system and in the direct-expansion system, the underground temperature will affect the size of the required ground-coupling system and the resulting operational effectiveness of the underground heat exchanger. Therefore, it is important to determine the underground soil temperature before selecting a system Figure 3. Mean annual soil temperatures. Source: OSU (1988). design. 10 FEDERAL ENERGY MANAGEMENT PROGRAM

Soil classifications include coarse- series requires greater antifreeze vol- grained sands and gravels, fine-grained umes; higher pipe cost per unit of silts and clays, and loam (equal mix- performance; increased installed tures of sand, silt, and clay). Rock classi- labor cost; limited capacity (length) fications are broken down into nine due to fluid pressure drop character- different petrologic groups. Thermal istics; larger pressure drop resulting conductivity values vary significantly in larger pumping load; requires within each of the nine groups. Each of larger purge system to remove air these classifications plays a role in de- from the piping network. termining the thermal conductivity and • Parallel-System Advantages: thereby affects the design of the Smaller pipe diameter has lower unit ground-coupling system. For more in- cost; lower volume requires less anti- formation on the thermal properties of freeze; smaller pressure drop result- soils and rocks and how to identify the ing in smaller pumping load; lower different types of soils and rocks, see installation labor cost. Soil and Rock Classification for the De- sign of Ground-Coupled Heat Pump • Parallel-System Disadvantages: Systems (STS Consultants 1989). Special attention required to ensure air removal and flow balancing Series versus Parallel Flow. Closed- between each parallel path to result loop ground-coupled heat exchangers in equal length loops. may be designed in series, parallel, or a combination of both. In series systems, Variations the heat transfer fluid can take only one path through the loop, whereas in par- The ground-coupling system is what allel systems the fluid can take two or makes the ground-source heat pump more paths through the circuit. The unique among heating and air- selection will affect performance, conditioning systems and, as described pumping requirements, and cost. above, there are several types of ground- Small-scale ground-coupling systems coupling systems. In addition, varia- tions to ground-source heat pump Figure 4. Soil temperature variation. can use either series or parallel-flow Source: OSU (1988). design, but most large ground-coupling design and installation can save addi- systems use parallel-flow systems. The tional energy or reduce installation advantages and disadvantages of series costs. Three notable variations are temperature variation (Figure 3b and and parallel systems are summarized described below. Figure 4b) becomes an important design below. In large systems, pressure drop consideration. Cooling-Tower-Supplemented Sys- and pumping costs need to be carefully tem. The ground-coupling system is Soil and Rock Classification. The considered or they will be very high. typically the largest component of the most important factor in the design and Variable-speed drives can be used to total installation cost of a ground-source successful operation of a closed-loop reduce pumping energy and costs heat pump. In southern climates or in ground-source heat pump system is the during part-load conditions. Total life- thermally heavy commercial applica- rate of heat transfer between the closed- cycle cost and design limitations should tions where the cooling load is the driv- loop ground-coupling system and the be used to design a specific system. ing design factor, supplementing the surrounding soil and rock. The thermal • Series-System Advantages: Single system with a cooling tower or other conductivity of the soil and rock is the path flow and pipe size; easier air supplemental heat rejection system can critical value that determines the length removal from the system; slightly reduce the required size of a closed-loop of pipe required. The pipe length, in higher thermal performance per lin- ground-coupling system. The supple- turn, affects the installation cost as well ear foot of pipe because larger pipe mental heat rejection system is installed as the operational effectiveness, which size required in the series system. in the loop by means of a heat exchanger in turn affects the operating cost. (typically a plate and frame heat Because of local variations in soil type • Series-System Disadvantages: exchanger) between the facility load and moisture conditions, economic Larger fluid volume of larger pipe in and the ground couple. A cooling tower designs may vary by location. system is illustrated in Figure 5. The

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cooling tower acts to precool the loop’s heat transfer fluid upstream of the ground couple, which lowers the cool- ing-load requirement on the ground- coupling system. By significantly reducing the required size of the ground-coupling system, using a cooling tower can lower the overall installation cost. This type of system is operating successfully in several com- mercial facilities, including some mis- sion-critical facilities at Fort Polk in Louisiana. Solar-Assisted System. In northern climates where the heating load is the driving design factor, supplementing the system with solar heat can reduce the required size of a closed-loop ground-coupling system. Solar panels, Figure 5. Cooling-tower-supplemental system for cooling dominated loads. designed to heat water, can be installed into the ground-coupled loop (by means of a heat exchanger or directly), as illus- System Design and Installation Systems are also zoned using commonly trated in Figure 6. The panels provide More is becoming known about the de- accepted design practices. additional heat to the heat transfer fluid. sign and installation of ground-source The key issue that makes ground-source This type of variation can reduce the heat pumps. Design day cooling and heat pumps unique is the design of the required size of the ground-coupled heating loads are determined through ground-coupling system. Most opera- system and increase heat pump traditional design practices such as tional problems with GSHPs stem from efficiency by providing a higher those endorsed by the American Society the performance of the ground-coupling temperature heat transfer fluid. of Heating, Refrigerating, and Air- system. Today, software tools are avail- Conditioning Engineers (ASHRAE). Hot Water Recovery/Desuperheating. able to support the design of the The use of heat pumps to provide hot water is becoming common. Because of their high efficiency, this practice makes economic sense. Most manufacturers of- fer an option to include desuperheating heat exchangers to provide hot water from a heat pump. These dual-wall heat exchangers are installed in the refriger- ant loop to recover high temperature heat from the superheated refrigerant gas. Hot-water recovery systems can supplement, or sometimes replace, con- ventional facility water-heating systems. With the heat pump in cooling mode, hot-water recovery systems increase system operating efficiency while acting as a waste-heat-recovery device—and provide essentially free hot water. When the load is increased during the heating mode, the heat pump still provides heat- ing and hot water more efficiently and less expensively than other systems. Figure 6. Solar-assisted system for heating dominated loads.

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Ground loops can be placed just about Ground Loop Design Software Review anywhere—under landscaping, parking Because of the diversity in loads in multizone buildings, the design of the ground-coupling heat ex- lots, or ponds. Selection of a particular changer (the ground loop) must be based on peak block load rather than the installed capacity. This ground-coupling system (vertical, hori- is of paramount importance because ground coupling is usually a major portion of the total ground- zontal, spiral, etc.) should be based on source heat pump system cost, and over-sizing will render a project economically unattractive. life-cycle cost of the entire system, in addition to practical constraints. Hori- In the residential sector, many systems have been designed using rules-of-thumb and local experi- zontal closed-loop ground-coupling ence, but for commercial-scale systems such practices are ill advised. For all but the most northern systems can be installed using a chain- climates, commercial-scale buildings will have significantly more heat rejection than extraction. This type trenching machine, horizontal imbalance in heat rejection/extraction can cause heat buildup in the ground to the point where heat boring machine, backhoe, bulldozer, pump performance is adversely affected and hence system efficiency and possibly occupant com- or other earth-moving heavy equip- fort suffer. Proper design for commercial-scale systems almost always benefits from the use of de- ment. Vertical applications (for both sign software. Software for commercial-scale ground-source heat pump system design should open and closed systems) require a consider the interaction of adjacent loops and predict the potential for long-term heat buildup in the drilling rig and qualified operators. soil. Some sources of PC-based design software packages that address this need are: Most applications of ground-source • GchpCalc Version 3.1, Energy Information Services, (205) 799-4591. This program includes heat pumps to large facilities use verti- built-in tables for heat pump equipment from most manufacturers. Input is in the form of heat cal closed-loop ground-coupling sys- loss/gain during a design day and the approximate equivalent full-load heating hours and tems primarily because of land equivalent full-load cooling hours. Primary output from the program is the ground loop length constraints. Submerged-loop applica- required. This program will also calculate the optimal size for a supplemental fluid cooler for tions require some special consider- hybrid systems, as discussed later. ations and, as noted earlier, it is best • GLHEPRO, International Association (IGSHPA), (800) 626-4747, to discuss these directly with an experi- http://www.mae.okstate.edu/Faculty/spitler/glhewin/glhepro.html. Input required is monthly enced design engineer. heating/cooling loads on heat pumps and monthly peak loads either entered directly by user or It is important to assign overall respon- read from BLAST or Trane System Analyzer and Trane Trace output files. The current configu- sibility for the entire ground-source heat ration of the program has some constraints on selection of borehole spacing, depth, and overall pump system to a single individual or layout that will be removed from a future version now being prepared. contractor. Installation of the system, • GS2000 Version 2.0, Caneta Research Inc., (905) 542-2890, email: however, will involve several trades [email protected]. Heating/cooling loads are input as monthly totals on heat pumps and contractors, many of whom may or, alternatively, monthly loads on the ground loop may be input. Equipment performance is not have worked together in previous input at ARI rating conditions discussed in Appendix E. For operating conditions other than the efforts. In addition to refrigeration/ rating conditions, the equipment performance is adjusted based on generic heat pump perfor- air-conditioning and sheet metal con- mance relationships. tractors, installation involves plumbers, Each of these programs requires input about the soil thermal properties, borehole resistance, type and (in the case of vertical systems) well of piping and borehole arrangement, fluid to be used, and other design parameters. Many of the drillers. Designating a singular respon- required inputs will be available from tables of default values. The designer should be careful to sible party and coordinating activities ensure that the values chosen are representative of the actual conditions to be encountered to will significantly reduce the potential ensure efficient and cost-effective designs. Test borings to determine the type of soil formations for problems with installation, startup, and locations will substantially improve design accuracy and may help reduce costs. Even and proper operation. with the information from test borings, some uncertainty will remain with respect to the soil thermal In heating-dominated climates, a mix- properties. These programs make it possible to vary design parameters easily within the range ture of antifreeze and water must be of anticipated values and determine the sensitivity of the design to a particular parameter (OTL used in the ground-coupling loops if 1999). In some instances, particularly very large projects, it may be advisable to obtain specific loop temperatures are expected to fall information on ground-loop performance by thermal testing of a sample borehole (Shonder and below about 5ºC (41ºF). A recent study Beck 2000). (Heinonen et al. 1997) establishes the important considerations for antifreeze solutions for ground-source heat pump ground-coupling system that meet the (IGSHPA). In addition, several manufac- systems and provides guidance on needs of designers and installers. These turers have designed their own propri- selection. tools are available from several sources, etary tools more closely tuned to their including the International Ground- particular system requirements (see One note of caution to the designer: Source Heat Pump Association side-bar discussion on design software). some regulations, installation manuals,

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and/or local practices call for partial or The regulatory requirements for vertical full grouting of the borehole. The ther- boreholes used for ground-coupling GSHP Super ESPC mal conductivity of materials normally heat exchangers vary widely by state. DOE has established national GSHP used for grouting is very low compared Current state and Federal regulations Super Energy Savings Performance with the thermal conductivity of most as well as related building codes are Contracts (Super ESPCs) with five native soil formations. Thus, grouting summarized at website http:// energy service companies (ESCOs) tends to act as insulation and hinders www.ghpc.com, as are contacts within that have demonstrated expertise in heat transfer to the ground. Some recent these regulatory bodies. the application of GSHP systems experimental work (Spilker 1998) has through past performance and propos- confirmed the negative impact of grout Federal Sector Potential als for specific projects. Through this on borehole heat transfer. Under heat The ground-source heat pump technol- mechanism, every Federal site has rejection loading, average water tem- ogy applied to Federal and other large access to at least five quality sources perature was nearly 6ºC (11ºF) higher facilities has been assessed by the New for the family of GSHP systems. for a 16.5-cm (6.5-in.) diameter borehole Technology Demonstration Program as backfilled with standard bentonite grout having significant potential for energy In an ESPC, an ESCO bears the costs than for a 12.1-cm (4.75-in.) diameter savings in the Federal sector. of implementing energy-savings borehole backfilled with thermally en- measures in exchange for fixed hanced bentonite grout. Using fine sand Technology Screening Process payments from the resulting cost as backfill in a 16.5-cm (6.5-in.) diameter savings. FEMP has implemented a The new technologies presented in the borehole lowered the average water “Super ESPC” to streamline the pro- Federal Technology Alerts are identified temperature over 8ºC (14ºF) compared cess of procuring GSHP-centered primarily through direct submittals with the same-diameter bore backfilled projects. A GSHP system must be the from Federal agencies to the program’s with standard bentonite grout. For a major focus, but other energy conser- Interlaboratory Council (ILC). The ILC typical system (Spilker 1998) with a vation measures (e.g., lighting im- also identifies new technologies through 16.5-cm (6.5-in.) diameter borehole, the provements) can be included if they trade journals, product expositions, use of standard bentonite grout would make the project more economical. trade associations, other research pro- increase the required bore length by 49% FEMP has selected and pre-approved grams, and other interested parties. over fine sand backfill in the same bore- a pool of ESCOs with which Federal Based on these responses, the technolo- hole. By using thermally enhanced agencies can contract. Under the Su- gies are evaluated by the ILC in terms of grout in a smaller 12.1-cm (4.75-in.) per ESPC, delivery orders can be Federal sector potential energy savings, borehole, the bore length is increased by awarded and facility managers procurement, installation and mainte- only 10% over fine sand backfill in the have the assurance that all of the nance costs. Ground-source heat pumps larger 16.5-cm (6.5-in.) diameter bore- selected ESCOs are qualified to applied to large facilities were judged to hole. Thus, the results of this study deliver top-quality GSHP-centered have notable potential and to be life- (Spilker 1998) suggest three steps that energy efficiency projects. cycle cost-effective in the proper may be taken to reduce the impact of applications. The advantages of GSHP-centered grout on system performance: projects under the Super ESPC • Reduce the amount of grout used to Estimated Savings and Market include: (1) ensures alignment with the bare minimum. Sand or cuttings Potential ESPC statutory authority and full com- may be used where allowed, but take An assessment aimed at estimating the pliance with all Federal procurement care to ensure that the entire intersti- Federal sector potential for ground- regulations applying to performance tial space between the piping and the source heat pumps applied to large contracting, (2) guarantees adequate borehole diameter is filled. facilities was performed by the Pacific operating budgets. • Use thermally enhanced grout wher- Northwest National Laboratory. The Additional information on the ever possible. For information on energy savings and market potential of technology-specific GSHP thermally enhanced grout consult the technology was evaluated using a Super ESPC can be found at ASHRAE (1997) and Spilker (1998). modified version of the FEDS software www.eren.doe.gov/femp/ tool developed for the U.S. Department financing/ghp.html. • Reduce the borehole diameter as of Energy’s Office of Federal Energy much as possible to mitigate the Management Program (FEMP), the effects of the grout or backfill used. U.S. Army Construction Engineering Research Laboratories (USA CERL), and the Naval Facilities Engineering Service

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Center (NFESC) by Pacific Northwest ation buildings, restaurant and dining There are several techniques to estimate National Laboratory (Dirks and facilities, commissary and exchanges, the annual energy consumption of Wrench 1993). and others. DOE, through FEMP, has ground-source heat pump systems. provided $500 million in contracting The most accurate methodologies use The assessment, originally performed in authority for Federal sites to procure computer simulation, and several soft- 1997, used the economic basis required ground-source heat pumps through ware systems now support the analysis in 10 CFR 436. The results of the assess- private sector financing. of ground-source heat pumps. These ment indicated that the application of methods, while more accurate than ground-source heat pumps applied to Application hand techniques, are also difficult and larger, non-residential, facilities in the expensive to employ and are therefore Federal sector could yield cost-effective This section addresses technical aspects more appropriate when additional savings in excess of 120,000 million Btu of applying ground-source heat pumps. detail is required rather than as an initial per year over conventional HVAC The range of applications and climates screening tool. technologies, for a net-present value in which the technology has been of $3.7 million. The initial cost of the installed are discussed. The advantages, The bin method is another analytical technology installations in cost- limitations, and benefits are enumer- tool for screening technology applica- effective Federal applications was ated. Design and integration consider- tions. In general, a bin method is a estimated to total around $15.6 million. ations for ground-source heat pumps simple computational procedure that is are highlighted, including energy readily adaptable to a spreadsheet-type Laboratory Perspective savings estimates, equipment warran- analysis and can be used to estimate the ties, relevant codes and standards, Through laboratory testing, field testing, energy consumption of a given applica- equipment and installation costs, and and theoretical analysis, the ground- tion and climate. Bin methods rely on utility incentives. source heat pump technology has been load and ambient wet and dry bulb tem- perature distributions. This methodol- shown to be technically valid and eco- Application Screening nomically attractive in many applica- ogy is used in the case study presented tions. Performance and capacity of the A ground-source heat pump system is in this Federal Technology Alert. technology do not degrade substantially one of the most efficient technologies as outside temperatures reach extremes, available for heating and cooling. It can Where to Apply Ground-Source either high or low, as do air-source heat be applied in virtually any climate or Heat Pumps pumps. Therefore, efficiency remains building category. Although local site Ground-source heat pumps are gener- high, and backup or supplementary conditions may dictate the type of ally applied to air-conditioning and systems are sometimes unnecessary. ground-coupling system employed, heating systems, but may also be used in The only remaining barriers to rapid the high first cost and its impact on the any refrigeration application. The deci- implementation involve user awareness overall life-cycle cost are typically the sion whether to use a ground-source and acceptance (which is growing rap- constraining factors that can be offset heat pump system is driven primarily idly), and higher initial implementation by the ESPC. by economics. Almost any HVAC sys- costs than other options. This Federal The operating efficiency of ground- tem can be designed using a ground- Technology Alert is intended to address source heat pumps is very dependent source heat pump. The primary these concerns by reporting on the on the entering water temperature, technical limitation is a suitable location collective experience of ground-source which, in turn, depends on ground tem- for the ground-coupling system. The heat pump users and evaluators and by perature, system load, and size of following list identifies some of the best providing application guidance. ground loop. As with any HVAC sys- applications of ground-source heat pumps. While ground-source heat pumps are tem, the system load is a function of the making progress in residential markets, facility, internal activities, and the local • Ground-source heat pumps are this technology can also be applied to weather. Furthermore, with ground- probably least cost-prohibitive in any heating and/or cooling require- source heat pumps, the load on the new construction; the technology is ment. Application of ground-source ground-coupling system may impact relatively easy to incorporate. heat pumps offers significant potential the underground temperature. There- • Ground-source heat pumps can also energy savings to a wide range of fore, energy consumption will be closely be cost-effective to replace an existing commercial-type facilities at Federal tied to the relationship between the system at the end of its useful life, or installations: administrative offices, hos- annual load distribution and the annual as a retrofit, particularily if existing pitals and clinics, schools and training ground loop-temperature distribution ductwork can be reused with mini- facilities, communications facilities, (e.g., their joint frequency distribution). mal modification. dormitories and hotels, clubs and recre- 15 FEDERAL ENERGY MANAGEMENT PROGRAM

• In climates with either cold winters The initial cost of the ground-source sionals, none of whom understands or hot summers, ground-source heat heat pump system is one of the prime or appreciates the other two parts of pumps can operate much more effi- barriers to the economics. In locations the system, then the system may not ciently than air-source heat pumps or with a significant ground-source heat perform satisfactorily. other air-conditioning systems. pump industry infrastructure (such as • One of the most frequent problems Ground-source heat pumps are also Oklahoma, Louisiana, Florida, Texas, cited is improper sizing of the heat considerably more efficient than and Indiana), installation costs may pump or the ground-coupling sys- other systems and, be lower and the contractors more tem. Approved calculation proce- depending on the heating fuel cost, experienced. This, however, is changing dures should be used in the sizing may be less expensive to operate than as the market for ground-source heat process—as is the case with any heat- other heating systems. pumps grows. ing or air-conditioning system re- • In climates characterized by high What to Avoid gardless of technology. ASHRAE has daily temperature swings, ground- established one of the most widely source heat pumps show superior The following precautions should be fol- known and accepted standards for efficiency. In addition, in climates lowed when the application of ground- the determination of design heating characterized by large daily tempera- source heat pump technology is and cooling loads. Sizing the ground- ture swings, the ground-coupling considered: coupling system is just as critical. system also offers some thermal • Avoid threaded plastic pipe connec- Because of the uncertainty of soil storage capability, which may benefit tions in the ground loop. Specify conditions, a site analysis to deter- the operational coefficient of thermal fusion welding. Unlike con- mine the thermal conductivity and performance. ventional water-source heat pump other heat transfer properties of the local soil may be required. This • In areas where natural gas is not systems where the water loop tem- ° ° should be the responsibility of the available or where the cost of natural perature ranges from 60 to 90 F ° ° designing contractor because it can gas or other fuel is high compared (15.6 to 32.2 C), ground-source sys- significantly affect the final design. with electricity, ground-source heat tems are subject to wider tempera- ° ° ° pumps are economical. They operate ture ranges (20 to 110 F [-6.7 to • Avoid inexperienced designers and ° with a heating coefficient of perfor- 43.3 C]), and the resulting expansion installers (see above). Check on the mance in the range of 3.0 to 4.5, com- and contraction may result in leaks at previous experience of potential de- pared with conventional heating the threaded connection. It is also signers and installers. It is also gener- efficiencies in the range of 80% to generally recommended to specify ally recommended to specify 97%. Therefore, when the cost of elec- piping and joining methods ap- IGSHPA certified installers. tricity (per Btu) is less than 3.5 times proved by International Ground- that of conventional heating fuels Source Heat Pump Association Design and Equipment Integration (IGSHPA). (per Btu), ground-source heat pumps The purpose of this Federal Technology have lower energy costs. • Check local water and well regula- Alert is to familiarize the Federal energy • Areas of high natural gas (or fuel oil) tions. Regulations affecting open- manager and Federal facility engineer costs will favor ground-source heat loop systems are common, and local with the benefits and liabilities of pumps over conventional gas (or fuel regulations can vary significantly. ground-source heat pumps in their oil) heating systems. High electricity Some local regulations may require application to Federal facilities. It is costs will favor ground-source heat reinjection wells rather than surface beyond the scope of this Federal Tech- pumps over air-source heat pumps. drainage. Some states require permits nology Alert to fully explain the design to use even private ponds as a heat requirements of a ground-source heat • In facilities where multiple tempera- source/sink. pump system. It is, however, important ture control zones or individual load that the reader know the basic steps in • Have the ground-source heat pump control is beneficial, ground-source the design process. heat pumps provide tremendous system installed as a complete and capability for individual zone balanced assemblage of components, The design of a ground-source heat temperature control because they are each of which must be properly pump system will generally follow the primarily designed using multiple designed, sized, and installed following sequence: (Giddings 1988). Also, have the sys- unitary systems. 1. Determine local design conditions, tem installed under the responsibility climatic and soil thermal • In areas where drilling costs are low, of a single party. If the entire system is characteristics. vertical-loop systems may be espe- installed by three different profes- cially attractive. 16 FEDERAL ENERGY MANAGEMENT PROGRAM

2. Determine local water, well, and sources are available to simplify the Warranties should also be requested for grouting requirements task. First, an experienced design con- the ground-coupling system, which is tractor should be assigned responsibility less common. Some installers and pipe 3. Determine building heating and for the heat pump and ground-coupling manufacturers have offered limited cooling loads at design conditions. system designs. Several manufacturers ground-coupling system warranties as 4. Select the alternative HVAC system of ground-source heat pump equipment long as 50 years. Quality control in the components, including the indoor have their own software tools to support installation of the ground-coupling sys- air-distribution system type; size the design of large, commercial-type tem has been a concern in the industry. the alternatives as required; and systems. However, for those who typi- The IGSHPA now offers training and select equipment that will meet the cally design systems in-house, there are certification programs for installers. In demands calculated in Step 2 (using support tools available. Software pro- addition, the IGSHPA also adminis- the preliminary estimate of the grams are available to support the design ters a registration program for those entering water temperatures to of ground-source heat pump HVAC organizations in the industry. These ser- determine the heat pump’s systems and the ground-coupling sys- vices have gone far to improve quality heating and cooling capacities tem. Several software tools are avail- control and customer satisfaction. and efficiencies). able through the IGSHPA, including an The track records reported in the litera- Earth-Coupled Analysis Program and a 5. Determine the monthly and annual ture for the ground-coupling systems Ground-Loop Heat Exchanger Design building heating and cooling energy are good. In cases where pipe joints Program. In addition, several techni- requirements. were thermal welded and followed the cal design manuals also are available standards recommended by IGSHPA, 6. Make preliminary selection of a through IGSHPA, ASHRAE, and equip- systems have proven reliable and resis- ground-coupling system type. ment manufacturers (refer to earlier tant to system leaks. section for an introduction to ground- 7. Determine a preliminary design of loop design software). the ground-coupling system. Energy Codes and Standards 8. Determine the thermal resistance of There are several different approaches Applications of ground-source heat the ground-coupling system. for incorporating ground-source heat pumps are subject to building and facil- pumps into the HVAC design. How- ity energy codes and standards. In addi- 9. Determine the required length of the ever, most applications in large facilities tion, the equipment used is subject to ground-coupling system; recalculate involve multiple smaller heat pump commercial equipment energy codes the entering and exiting water units (<20 ton) applied in a modular and standards. Most energy regulations temperatures on the basis of system zone control system and connected to a that impact Federal facilities derive loads and the ground-coupling common water loop and associated from ASHRAE standards, specifically system design. ground-coupling system. Although ASHRAE Standard 90.1. The code that 10. Redesign the ground-coupling some agencies are experimenting with currently governs the selection of alter- system as required to balance the larger equipment sizes, most manufac- native energy technologies by life- requirements of the system load turers are supporting the development cycle costing in Federal facilities is (heating and cooling) with the effec- of efficient smaller systems (1/2 ton to 10 CFR 436 Subpart A. Minimum equip- tiveness of the ground-coupling sys- 15 tons [1.8 to 52.8 kW]). ment efficiency standards, as identified tem. Note that designing and sizing in ASHRAE Standard 90.1-1999, for com- Equipment Warranties the ground-coupling system for one mercial equipment relative to ground- season (such as cooling) will impact The prospective user should ask poten- source heat pumps are shown in Table 1. tial suppliers, contractors, and installers its effectiveness and ability to meet Although codes and standards identify about equipment warranties. The heat system load requirements during minimum efficiencies such as those pump equipment is typically guaran- the other season (such as heating). identified above, they do not fully teed free from manufacturer defects 11. Perform life-cycle cost analysis on communicate the energy efficiency that from 1 to 5 years. Some manufacturers is achieved by today’s heat pumps. A the system design (or system design offer extended warranties up to 10 review of manufacturer’s literature on alternatives). years. Residential applications have commercially available equipment Although the design procedure for the been found to have longer warranties indicates that cooling efficiencies (EERs) ground-coupling system is an iterative than commercial applications. of 12.0 to 16.8 Btu/W-h and heating and sometimes difficult process, several

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Table 1. Minimum commercial equipment efficiency rating standards (ASHRAE 90.1-1999), effective 10/29/2001.

Rating Condition Minimum Performance Reference (enter water as of 10/29/2001 Technology Application Standard Category (capacity) temperature) Cooling Heating Water-Source Heat Pumps ISO-13256-1(a) <17 kBtuh Standard 86°F (30°C) 11.2 EER - - - Standard 68°F (20°C) - - - 4.2 COP ≥17 kBtuh and <65 kBtuh Standard 86°F (30°C) 11.2 EER - - - Standard 68°F (20°C) - - - 4.2 COP ≥65 kBtuh and < 135 kBtuh Standard 86°F (30°C) 12.0 EER - - - Standard 68°F (20°C) - - - 4.2 COP Groundwater- Source Heat Pumps ISO-13256-1 <135 kBtuh Standard 59°F (15°C) 16.2 EER Standard 68°F (20°C) 4.2 COP Ground-Source Closed-Loop Heat Pumps ISO-13256-1 <135 kBtuh Standard 77°F (25°C) 13.4 EER - - - Standard 32°F (0°C) - - - 3.1 COP (a) ISO 13256-1 (1998) Water-Source Heat Pumps - Testing and Rating for Performance - Part 1: Water -to-Air and Brine-to-Air Heat Pumps. efficiencies (COPs) of 3.0 to 4.3 are Institute (EPRI) identified 136 utility ity of new ground-source heat pump readily available.(d) When comparing programs specific to ground-source heat installations in the United States are for equipment efficiencies, it is important to pumps and water-loop heat pumps residential applications in the southern make an appropriate comparison. The (EPRI 1993). This report summarized a and mid-western states. Environmental efficiency of any heating or cooling survey that identified 2,321 DSM pro- concerns and a general lack of under- equipment varies with application, load, grams from 666 utilities. Rebates for standing of the technology by HVAC and related heat-source and heat-sink ground-source heat pumps identified companies and installers have limited temperatures. Furthermore, standard in the survey ranged from $15 to $600 installations in the west. ratings are for specific temperatures and per ton, with an average of $190/ton, operating conditions. Standard ratings and $100 to $2,000 per unit, with an Field Experience do not necessarily reflect the efficiency average of $538/unit. In addition to the Observations about field performance of systems under true seasonal operat- technology-specific rebate programs, of ground-source heat pumps obtained ing conditions. In determining the effi- some utilities also offer custom rebate from Federal and private-sector users ciency of heating or cooling equipment programs or programs that are not are summarized in this section. for estimating energy consumption or technology specific but are based on the potential energy savings, the efficiency energy savings regardless of the technol- The large number of reported installa- should be corrected for the appropriate ogy employed. Readers are encouraged tions testify to the stability of this tech- operating conditions. to contact their local utility to find out nology. Most sites contacted report more about what programs, services, satisfaction with the overall perfor- Utility Incentives and Support and rebates may be offered by the utility mance (energy efficiency, maintenance, and comfort) of the technology. The Many utilities are promoters of ground- to promote energy management and world’s largest installation of ground- source heat pumps, and many offer in- new energy-efficient technologies. source heat pumps is at Fort Polk, centive programs and support. Electric Louisiana, where over 4000 units were utilities are expected to offer Federal Technology Performance installed in family housing as part of agencies private financing and expertise In 1999, an estimated 400,000 ground- a major retrofit project (Hughes and to implement GSHP projects through source heat pumps were operating in Shonder 1998). They also have systems the existing Utility Energy Services residential and commercial applications, installed in several larger facilities, Contracts (UESCs). up from 100,000 in 1990. With a pro- including some cooling-tower hybrid jected annual growth rate of 10%, In a recent publication reporting current systems (discussed earlier in this Federal 120,000 new units would be installed in demand-side management (DSM) Technology Alert). Personnel at Fort 2010, for a total of 1.5 million units in programs, the Electric Power Research Polk are obviously pleased with the per- 2010 (Lund and Boyd 2000). The major- formance of their ground-source heat

(d) For more information on the various terms used to define efficiency in HVAC systems (see Appendix C). 18 FEDERAL ENERGY MANAGEMENT PROGRAM

pumps, and the energy manager Alert, the type of soil and rock in contact comfortable, complaint-free environ- reports that the systems have performed with the pipe loop has serious implica- ment (Shonder et al. 1999). better than expected and they plan to tions for the length of ground loop Additional case studies are identified on use the technology for all heating and required for adequate heat transfer. the Geothermal Heat Pump Consortium cooling requirements on the base. Inexperienced designers or installers Web page (http://www.ghpc.org/). are more likely to undersize the sys- The maintenance engineer at the hospi- tems, resulting in inadequate system tal in Love County, Oklahoma, reported Energy Savings performance, or to oversize the systems, that no problems have occurred since resulting in increased installation costs. The most important reason to consider nine units were installed in their facility The importance of good design, docu- the application of ground-source heat in the early 1990s. They perform routine mentation, installation, and commis- pumps to Federal facilities is the poten- maintenance on the system. They sioning cannot be overemphasized. tial energy savings and its impact on particularly like the technology because overall life-cycle cost of the heating and it takes up less space and gives better In early 1995, at the National Training cooling system. Ground-source heat heating and cooling control than Center in Fort Irwin, California, 220 new pumps save energy and money because former systems. single-family houses were built with an the equipment operates more efficiently innovative ground-source heat pump An interview with the energy manager than conventional systems, the mainte- system. The thermal sink/source for the primarily responsible for the ground- nance costs are lower (see next section heat pumps is geothermally heated 75ºF source heat pump installation at the for maintenance benefits), and the groundwater. The groundwater is Oklahoma State Capitol Building equipment has a longer life expectancy. pumped into a storage reservoir adja- revealed no problems with the heat In addition, a ground-source heat pump cent to the housing project. The reser- pumps or the ground loop; however, does not require a defrost cycle, or, in voir water is then circulated through a the building was poorly zoned, which most situations, backup electric resis- double-walled heat exchanger, transfer- impeded effective temperature control. tance heat, as do air source heat pumps. ring thermal energy to/from a second- Approval from the local Water Resource ary closed circulation loop connected to By comparison, the average cooling Board for drilling the wells proved individual heat pumps in each resi- efficiency at Federal commercial-type difficult but was primarily a matter of dence. Operating conditions and prob- facilities is estimated to be an EER of educating the board about the technol- lems with maintaining correct water 8.0 (2.33 COP) for existing facilities and ogy and the closed-loop system. The flow through the central facility heat an EER of 10.0 (2.93 COP) for new facili- Capitol building system, which is a exchanger contributed to lower than ties. Ground-source heat pump systems cooling-tower-supplemented design, expected energy savings during the first have the potential to reduce consump- contains 855 cooling tons (3,009.6 kW) year of operation. There was no indica- tion of cooling energy by 30% to 50% connected to a common ground-loop tion that the heat pumps themselves and to reduce heating energy by 20% system consisting of 372 250-foot were not performing as designed. to 40% compared with typical air-source (76.2 m) vertical wells. Limited anecdotal information from the heat pumps. One facility manager did report prob- occupants indicates that overall satisfac- A review of manufacturing literature on lems with the ground-source heat pump tion with the level of commercially available systems indicates system installed in a facility at the from the system was high.(e) that cooling efficiencies (EERs) of 12.0 to Dugway Proving Grounds, Utah. The Vertical-bore, ground-coupled heat 16.8 Btu/w-h and heating efficiencies system contains 22.5-ton (8.8 kW) units. pump systems were installed in four (COPs) of 3.0 to 4.3 are readily available Although the actual problem has not (f) new elementary schools in Lincoln, (ARI 330 ratings ). A study prepared by been identified, the system is not per- Nebraska, in 1995. Each school required DOE estimates energy-saving ranges of forming up to expectations. The current 54 heat pumps ranging in size from 1.4 17% to 42% comparing ground-source belief is that the ground-loop is under- to 15 tons (204-tons total cooling capac- heat pumps to air-source heat pumps, sized. Sizing of the ground loop is one of ity). With the heat pump systems, utility depending on region (Calm 1987). the most important design factors and is costs for these four schools and nearly Figure 7 illustrates the range of efficien- a function of system load, ground tem- half of that of other schools in the dis- cies typical of various heating and cool- perature, and local soil conditions. As trict, and the systems are providing a ing equipment. noted earlier in this Federal Technology

(e) D.L. Hadley and L. Lkevgard. August 1997. Family Housing Energy Savings Verification, National Traning Center, Fort Irwin, CA. Preliminary Findings: Cooling Season Energy Savings. Letter Report, Pacific Northwest National Laboratory, Richland, Washington. (f) ARI test rating conditions are described in Appendix E.

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1999, 2000). The results of these studies are summarized in Table 2. Another analysis, this one by the Geo- thermal Heat Pump Consortium, found that the average total preventive and corrective maintenance costs for 25 GSHP-equipped buildings were approximately 11 cents/ft2, compared to 30 to 40 cents/ft2 for conventional systems (Cane 1998).

Installation Costs Application-specific parameters, such as equipment capacity, type, refrigerant, air-distribution system, control system, plumbing configuration, and ground- coupling system type, significantly Nominal Coefficient of Performance affect the total cost of the overall system. While equipment costs are competitive, installation costs vary significantly. Figure 7. Typical heating and cooling equipment efficiencies. To illustrate the potential range of instal- lation costs, the following examples Maintenance system, and the water loop (a closed have been reported. The ground-source heat pump technol- system) should be routinely monitored for temperature, pressure, flow, and • Stockton State College in Pomona, ogy is mature and reliable. Systems have New Jersey, retrofit a system that to- standard warranties ranging from 1 to antifreeze concentration. Unless there is a leak, no action is generally required. taled 1,655 tons (5,826 kW) at a total 5 years. The heat pump units are self- cost of $5,246,000 (Gahran 1993). The contained, and maintenance require- In open-loop systems, the well requires facility received grants and rebates ments are relatively straightforward; no maintenance similar to any water well. reducing the capital outlay to new maintenance skills are necessary. The system should be routinely moni- $135,000. The system included Because heat pump equipment is not tored for temperature, pressure, and 63 rooftop units, 500 variable-air exposed to outdoor elements, the units flow. Because groundwater is being sup- volume (VAV) boxes, and a 3,500- actually require less maintenance than plied to the heat pump, the heat point energy management control typical air-source heat pumps. One site exchangers should be routinely system (EMCS). The unit cost was reported a problem with cottonwood inspected for potential fouling and $3,170/ton in 1993 dollars. trees clogging outside condenser units scale buildup. of the previous air-conditioning systems. • WaterFurnace, a ground-source heat This maintenance problem was elimi- Maintenance costs for GSHPs are about pump manufacturer, designed the nated with the application of ground- the same or less than conventional technology using a submerged pond source heat pumps. equipment. For example, maintenance closed-loop system into its new office costs for four new schools in the Lincoln, building located in Fort Wayne, Indi- In closed-loop systems, the ground loop Nebraska, equipped with GSHP sys- ana. The system totaled 134 tons is virtually maintenance free. The circu- tems have been thoroughly docu- (471.7 kW) at a cost of $239,800 lating pump(s) requires routine mainte- mented in recent years (Martin et al. (WaterFurnace WF639). The unit cost nance, as with any pump and motor was $1,790/ton in 1991 dollars.

Table 2. Maintenance costs for public schools in Lincoln, Nebraska. • Salem Community College in Carney’s Point, New Jersey, retrofit a Preventive system that totaled 160 tons at a total Maintenance Repair Total HVAC System Type (cents/yr-ft2) (cents/yr-ft2) (cents/yr-ft2) cost of $284,000 (Gahran 1994). The system included 32 heat pumps. GSHP system 7.1 2.1 9.2 The unit cost was $1,775/ton in Conventional system 5.9 - 12.6 2.9 - 6.1 8.8 - 18.7 1993 dollars.

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• Paint Lick Elementary School Other Impacts technologies, from simplistic degree- in Garrard County, Kentucky, There are no significant negative environ- day calculations to sophisticated designed the technology into the mental impacts associated with ground- hour-by-hour energy modeling and new school building. The system source heat pumps. There is, however, simulation systems supported by com- totaled 123 tons (433 kW) at a total the potential for systems to be affected puter programs. The examples used in cost of $380,010 (WaterFurnace by some local codes and regulations. this Federal Technology Alert are based WF666). The unit cost was $3,090/ The most likely source of conflict, if any, on an outdoor temperature bin method. ton in 1992 dollars. lies with the installation of the ground- This method is described in more detail in Closed-Loop/Closed-Source Heat Pump • Maywood Elementary School coupling system. Working with an Systems: Installation Guide (OSU 1988). in Hammond, Indiana, designed experienced installer is the best advice. the technology into a new school However, local electric utilities and other Two case studies were developed for building. The unit totaled 250 tons local sites with existing ground-source this Federal Technology Alert. In both, (880 kW) at a total cost of $1,277,190 heat pump installations are other sources estimates of the potential energy con- (WaterFurnace WF925). The system of information about local permit and sumption and life-cycle costs of the consisted of 74 heat pumps and a regulation issues. ground-source heat pump technology ground-coupling system consisting With the application of any electro- are compared with conventional HVAC of 244 vertical wells. The unit cost technology, there is a potential technologies. In each study, the facility was $5,110/ton in 1994 dollars. environmental benefit. Installing a is a hypothetical Federal administrative building of typical single-story con- • The Lincoln, Nebraska, school dis- ground-source heat pump system in struction. The facilities in each example trict installed ground-source heat lieu of a fossil-fuel will operate continuously (no night setback pump systems in four new elemen- reduce local emissions. Furthermore, temperature control). In the first example, tary schools. In each school, the sys- installing a more efficient electro- the building is located in upstate New tem consisted of 54 heat pumps technology such as a ground-source York; in the second example, the same ranging in size from 1.4 tons to heat pump system for cooling will building is located in central Oklahoma. 15 tons, with a total cooling capacity reduce source emissions at the utility power plant. Typical emission reduc- of 180 tons (630 kW). Four gas-fired Example 1: Upstate New York Facility boilers with a capacity of 330,000 tions per MWh of energy conserved Btuh each provide hot water for pre- are 0.3 pounds (0.14 kg) of , The facility is in upstate New York near heat and terminal reheat. The total 3.3 pounds (1.5 kg) of sulfur oxides, Griffiss Air Force Base. Mean local ° heat pump cost per school was ap- 5.3 pounds (2.4 kg) of nitrogen oxides, weather conditions are 7,331 (base 65 F) proximately $657,000 ($3,650/ton) in and 1,720 pounds (780 kg) of carbon heating degree-days (4,073 heating Cel- ° 1995 dollars (Shonder et al. 1999). dioxide. These numbers vary with sius degree-days) and 472 (base 65 F) time and region, depending on the cooling degree-days (262 cooling Cel- • Kavanaugh (1995) concluded that the power generation fuel mix (EPA 1994; sius degree-days). The 97.5% heating average cost of ground-source heat Nemeth 1993). design temperature is -5°F (-20.6°C) and pumps (including unit, loop, , the 2.5% cooling design temperature is and installation) ranged from $2360 Case Studies 85°F (29.4°C). The mean annual earth per ton for a 5-ton horizontal loop to ° ° The purpose of these case studies is to temperature is 49 F (9.4 C). $3000 per ton for a 3-ton vertical loop assist the Federal energy manager or system. Compared to a 3-ton conven- The local utility in this region (for facility engineer in estimating the energy tional system, the added cost was electric and natural gas) is Niagara consumption and costs associated with $1250 to $1550 per ton. Mohawk. The electric rate schedule for the construction and operation of this example consists of a demand Installation costs are expected to drop as ground-source heat pump systems and charge of $5.51/kW-month and an the ground-source heat pump industry comparing them with those for conven- energy charge of $0.05/kWh. The gas infrastructure grows and designers and tional HVAC technologies. The goal is rate schedule consists of an energy installers become more experienced. to estimate energy consumption and charge of $0.54/therm. Reducing installation costs is one of the savings, not to design systems. prime goals of the International Ground- The heating load for this facility during There are several methods for estimat- Source Heat Pump Association and the the design day is estimated to be 3,309 ing energy consumption of HVAC Geothermal Heat Pump Consortium. kBtu/h (970.6 kW). The design cooling

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load is 1,273 kBtu/h (373.4 kW). The bal- design day, each rooftop unit is loads or a thermally massive structure, ance temperature for the facility is 60°F equipped with 125-kW supplemental which tends to “hold” the heat or cold. (15.6°C). The balance temperature is the heaters. The estimated equipment life of In the case of a “thermally heavy” facil- temperature at which neither heating this alternative, according to ASHRAE, ity, the building heating and cooling nor cooling is required to meet the com- is 15 years (ASHRAE 1995, p. 33.4). loads would have to be calculated using fort requirements of the facility. a methodology other than the one uti- The third alternative is a ground-source lized in the following analysis. Technology Description. Three tech- heat pump system using extended- nologies are compared in this example. range water-source heat pumps and a The analysis shown in Table 3 begins The conventional technology is a roof- vertical closed-loop ground-coupling with an estimate of the building load for top air-conditioning system with inte- system. For this example, the capacity each bin. Column 1 indicates the mid- gral natural gas heaters. For this and input power are based on a com- point of each temperature bin, e.g., the example, the capacity and input power mercially available ground-source heat bin from 95° to 99°F has a midpoint tem- are based on a commercially available pump. The heat pumps have a rated perature of 97°F. Column 2 gives the rooftop unit with a rated heating capac- cooling capacity of 57.5 kBtu/h (16.9 number of hours that occur in each bin ity of 270 kBtu/h (79.2 kW) and a rated kW) and a rated heating capacity of 60.0 over a “typical” year. Column 3 esti- cooling capacity of 162 kBtu/h (47.5 kBtu/h (17.6 kW) at ARI 330 conditions. mates the corresponding building load. kW) at ARI conditions. The equipment The equipment selected has a rated cool- This is calculated by linear interpolation selected has a cooling efficiency of 8.2 ing efficiency of 14.49 EER and a rated between no heating or cooling load at EER and 10.1 IPLV(g) at ARI conditions. heating efficiency of 4.0 COP. The indoor the facility balance temperature and the The heating efficiency is rated at 80%. air fan input power is included in the design heating or cooling load at the de- The indoor air fan is rated at 2.50 kW power input loads. To meet the cooling sign heating or cooling temperature. input and the outdoor air fans are rated requirements during the design day, The actual equations used in this analy- at 2.67 kW input. To meet the heating 22 units are required. To meet the added sis are listed in Appendix A, Table A.4. requirements during the design day, 13 load during the heating design day, each The entering water temperature (EWT) rooftop units are required. This number unit is equipped with a 33-kW supple- is estimated in Column 4 of Table A.4. also meets the cooling load require- mental heater. It is also assumed that the This is the temperature of the water en- ments. The estimated equipment life of water-loop system employs a variable- tering the heat pump from the ground- this alternative, according to ASHRAE, speed drive for added energy savings. coupling system. For initial estimating, is 15 years (ASHRAE 1995, p. 33.4). The estimated equipment life of this the entering water temperature is a lin- alternative, according to ASHRAE, is The second alternative is a rooftop air- ear interpolation between two points for 19 years (ASHRAE 1995, p. 33.4). source heat pump system with electric the heating cycle and again for the cool- resistance supplemental heaters. For this Savings Potential. Energy consumption ing cycle. During zero building load example, the capacity and input power for the three alternatives is estimated by conditions, which occurs at the facility are based on a commercially available an outdoor temperature bin method. balance temperature, the entering water air-source heat pump. The rooftop units The calculations are performed in a temperature is assumed to be equal to have a rated cooling capacity of 162 spreadsheet using 5°F bin data, because the ground temperature. During the kBtu/h (47.5 kW) and a rated heating this is the form in which data are readily peak load, the entering EWT is set to the capacity of 166 kBtu/h (48.7 kW) (high available to most Federal energy man- maximum temperature desired during temperature) and 102 kBtu/h (29.9 kW) agers (TM 5-785). the peak cooling season load; similarly, (low temperature) at ARI Standard 340 it is set to the minimum temperature The main assumption underlying this test conditions. The equipment selected desired during the peak heating season type of analysis is that the facility is has a rated cooling efficiency of 8.5 EER load. Publications by the International “thermally light.” This implies that the and a rated heating efficiency of 3.0 COP Ground-Source Heat Pump Association heating and cooling loads on the build- (high temperature) and 2.1 COP (low recommend for initial calculations these ing are proportional to the outside air temperature). The indoor and outdoor temperatures be set to 100°F maximum temperature. A “thermally heavy” facil- air fan input power is included in the (37.8°C) and 37°F (2.8°C) minimum, ity would be a building in which the power input loads. To meet the cooling although in this example, the minimum cooling load on the building is not very requirements during the design day, temperature was set to 35°F (1.7°C). proportional to the outside air tempera- seven rooftop units are required. To Today, most commercial systems are ture because of significant internal heat meet the added load during the heating commonly designed at 90°F (32.2°C)

(g) EER and IPLV have units of Btu/w-h in this example.

22 FEDERAL ENERGY MANAGEMENT PROGRAM

Table 3. Griffiss AFB ground-source heat pump energy consumption bin method analysis.

maximum EWT. The estimated entering run-time on the units. The part-load is the efficiency of the ground-source water temperatures are refined later in factor is dependent on the equipment heat pump alone and is determined by the design process as the ground- “degradation factor.” The degradation dividing the net capacity by the input coupling system design is finalized. factor is typically assumed to be 0.25 power and correcting for the appropri- unless the equipment manufacturer ate units of measure. The cooling effi- Column 5 in Table A.4 is the net capacity has tested the unit and determined a ciency is typically expressed as the of the ground-source heat pump equip- lower value. Energy-Efficiency Ratio (EER) and has ment. This is taken from equipment units of Btu/watt-h. Heating efficiency specifications based on the entering wa- Column 10 is the input power of the is typically expressed as the Coefficient ter temperature. Columns 6, 7, and 8 are ground-source heat pump equipment. of Performance (COP) and is a dimen- used to determine the loss in efficiency Like the net capacity, this is taken from sionless measure. due to part-load operating characteristics equipment specifications based on the of equipment, which result in increased entering water temperature. Column 9

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Column 11 is the average input power is estimated to be 1,413,207 kWh/yr. The at $213,000. The operations and mainte- required by the supplemental heaters monthly-billed demand is estimated by nance cost for the ground-source to meet the estimated building heating examining the corresponding tempera- heat pump system is estimated to be load. It is estimated by taking the differ- ture bin during the time the monthly $3,700/yr compared with $8,775/yr for ence between the building heating load peak demand is typically set for the the conventional system and $6,145/yr and the capacity of the heat pumps. facility. For this example, it is estimated for the air-source heat pump system. When the ground-source heat pumps that the demand is 4,355 kW-month/yr. Using the Building Life-Cycle Cost soft- can meet the building load, there is no ware (BLCC 4.0) available from the Not included in the sample equipment load on the supplemental heaters. The National Institute for Standards and design is an air-to-air heat recovery sys- maximum load does not exceed the in- Technology (NIST), the total life-cycle tem that would reduce the need for stalled capacity of the supplemental costs for the three alternatives are esti- supplemental electric resistance heating. heaters. Not included in this simplified mated at $1,502,942 for the ground- Heat pump manufacturers make these example is an air-to-air heat recovery source heat pump system, $1,552,326 for units available as part of the rooftop system that would reduce the need for the air-source heat pump system, and unit for installations in colder north- supplemental heating. These recovery $1,639,262 for the conventional system. ern climates. systems are common in cold region A common life-cycle of 15 years was applications and are part of the basic Similar spreadsheets were developed for used in this analysis. More on Federal rooftop unit. each of the other technology alternatives life cycle costing procedures and the using standard ASHRAE bin methods BLCC software can be found in The average pump flow rate in Col- and are shown in Appendix A. Appendix B. umn 12 is estimated based on the num- ber of heat pumps, the actual run time Life-Cycle Cost. The total installation A summary of the energy and cost (Column 8), and the rated flow per unit. cost, including material, labor, over- factors from the three alternatives is Most ground-source heat pumps are head, and profit, for the ground-source shown in Table 4. A comparison of the rated at around 3 gpm per ton of cool- heat pump option is $329,350 compared air-source heat pump system with the ing (0.054 L/s-kW), although manufac- with the conventional system at $454,100 ground-source heat pump alternative tures vary. and the air-source heat pump system using BLCC is illustrated in Figure 8. The ground-source heat pump energy Table 4. Example 1: summary of results. consumption, Column 13, is the result of the input power multiplied by the run Conventional Air-Source Heat Ground-Source Heat time multiplied by the number of hours Griffiss AFB, NY System Pump Pump in each bin (Column 10 x Column 8 x Number of units 13 7 22 Column 2). The supplemental heater Nominal capacity (tons) energy consumption is similarly esti- Each 13.5 13.5 4.8 mated as the result of the supplemental Total 175.5 94.5 105.6 heater power multiplied by the run time Supplemental heaters (kW) multiplied by the number of hours in Each n/a 125 33 each bin (Column 11 x Column 8 x Total n/a 875 726 Column 2). Equipment capacity (kBtu/h) (at design conditions) The energy consumption of the ground- Summer 2,535.0 1,360.1 1,270.1 coupling loop is dependent on the con- Winter 3,510.0 3,395.0 3,336.6 figuration of the ground-coupling and Energy Consumption (/yr) Electricity (kWh) 252,908 1,656,555 1,413,207 control systems. For this example, it is Demand (kW-mo) 1,481 4,200 4,355 assumed the net pressure rise of the circu- Natural gas (therm) 110,380 0 0 lation pump at full design flow is 48 psi Total energy (MBtu) 11,901 5,562 4,822 and that, due to the control system, the Energy Costs ($/yr) variable-speed drive reduces the energy Electricity 12,645 82,828 70,660 Demand 8,160 23,142 23,996 requirement as a square function of the Natural gas 59,605 0 0 flow rate. The total energy consumption Total energy 80,411 105,970 94,656 (Column 16) is the sum of the compo- O&M Costs ($/yr) 8,775 3,300 3,700 nent energy consumptions (Column 13 Installed Cost ($) 454,100 212,500 329,300 + Column 14 + Column 15). For the Equipment life (yr) 15 15 15 ground-source heat pump system in this Total Life-Cycle Cost ($) 1,639,262 1,516,482 1,502,942 example, the annual energy consumption 24 FEDERAL ENERGY MANAGEMENT PROGRAM

Example 2: Oklahoma City Facility This example places the same building in a new environment. The location of the facility is in Oklahoma City, Oklahoma. Typical local weather conditions are 3,588°F-day/yr (base 65°F) heating degree-days (1,993 heating Celsius degree-days) and 2,068 (base 65°F) cool- ing degree-days (1,149 cooling Celsius degree-days). The 97.5% heating design temperature is 13°F (-10.6°C) and the 2.5% cooling design temperature is 96°F (35.6°C). The mean annual earth tem- perature is 62°F (16.7°C). The local electric utility in this region is Oklahoma Gas & Electric Company (OG&E). The electric rate schedule for this example consists of a summer demand charge of $12.35/kW-month, a winter demand charge of $4.48/ kW-month, and an energy charge of $0.0236/kWh. The local natural gas utility is Oklahoma Natural Gas. The gas rate schedule consists of an energy charge of $3.40/mcf ($0.34/therm). The corresponding heating load for this facility during the design day is esti- mated to be 2,392 kBtu/h (701.7 kW). The design cooling load is 1,832 kBtu/h (537.4 kW). The same balance tempera- ture of 60°F (15.6°C) is estimated for the facility. Technology Description. The same three technologies are compared in this example, but the number of units has changed because the building loads are now different. The conventional tech- nology is a rooftop air-conditioning sys- tem with integral natural gas furnace heaters. To meet the cooling require- ments during the actual cooling design day, 10 rooftop units are required. This number also meets the heating load requirements. The second alternative is a rooftop air- source heat pump system with electric resistance supplemental heaters. To meet the cooling requirements during Figure 8. Building life-cycle cost (BLCC) output. the actual cooling design day, 10 roof- top units are required. To meet the

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added load during the heating design Table 5. Example 2: summary of results. day, each rooftop unit is equipped with a 50-kW supplemental heater. Conventional Air-Source Heat Ground-Source Heat Oklahoma City, OK System Pump Pump The third alternative is a ground-source Number of units: 10 10 35 heat pump system using extended- Nominal capacity (tons) range water-source heat pumps and a Each 13.5 13.5 4.8 vertical closed-loop ground-coupling Total 135 13.5 168 system. To meet the cooling require- Supplemental heaters (kW) ments during the actual cooling design Each n/a 50 10 day, 35 units are required. To meet the Total n/a 500 350 added load during the heating design Equipment capacity (kBtu/h) day, each unit is equipped with a 10-kW (at design conditions) Summer 1,848.0 1,822.7 1,864.6 supplemental heater. The water-loop Winter 2,700.0 2,621.0 2,611.5 system employs a variable-speed drive Energy Consumption (/yr) for added energy savings. Electricity (kWh) 467,708 850,469 687,333 Demand (kW-mo) Savings Potential. Energy consumption - Winter season 455 2,748 1,931 is estimated with the same spreadsheet - Summer season 842 770 770 temperature bin model as the previous Natural gas (therm) 54,081 0 0 case. The results are shown in Total energy (MBtu) 7,004 2,902 2,345 Appendix A and summarized in Energy Costs ($/yr) Electricity 11,038 20,071 16,221 Table 5. Demand 12,437 21,821 18,160 Natural gas 18,388 0 0 Life-Cycle Cost. The total installation Total energy 41,863 41,892 34,381 cost for the ground-source heat pump O&M Costs ($/yr) 6,750 4,725 5,880 option (including material, labor, Installed Cost ($) 349,300 236,000 451,500 overhead, and profit) is estimated to Equipment life (yr) 15 15 15 be $451,500, compared with the Total Life-Cycle Cost ($) 974,924 800,065 938,282 conventional system at $349,300 and the air-source heat pump system at $236,000. The operations and mainte- utility costs, and most importantly, than for other technologies, the decision nance cost for the ground-source local installation costs. The reader is criteria should be based on life-cycle heat pump system is estimated to be encouraged to perform similar costs rather than first costs (as required $5,880/yr, compared with $6,750/yr for calculations for a specific site. by 10 CFR 436); then, a ground-source heat pump system is frequently the most the conventional system and $4,725/yr The above examples assume that the cost-effective alternative. According to for the air-source heat pump system. facility will responsible for all costs the recent EPA study Space Conditioning: Through BLCC, the total life-cycle costs associated with the construction and The Next Frontier, GSHPs are consis- for the three alternatives were estimated operation of the installed GSHP system. tently the most energy-efficient, least to be $938,282 for the ground-source However, if the equipment were in- polluting of all space conditioning heat pump system, $800,065 for the stalled under the Super ESPC program, technologies throughout the country air-source heat pump system, and the installation cost could be zero and (EPA 1993). $974,924 for the conventional system. the economic justification for the project The fact that the ground-source heat would be significantly different. The limited industry volume has been pump system did not have the lowest one of the factors holding back the life-cycle cost in this evaluation should The Technology in development of a broader contractor not imply that ground-source heat Perspective base. The technology has not enjoyed pumps are never cost-effective in this The future of ground-source heat pump broad national promotion. According to region. On the contrary, the purpose of technology in the Federal sector looks the results of one survey on the barriers this example is to illustrate that the cost- good because there are many poten- to ground-source heat pumps, HVAC, effectiveness of ground-source heat tial commercial applications. Al- plumbing, and A/E contractors are con- pumps is a function of system heating though installation costs are typically servative, and are therefore reluctant to and cooling load requirements, local higher for ground-source heat pumps commit to what they regard as innova- tive and (to some) unproven technology

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and equipment (Technical Marketing 120,000 new units would be installed YMCA Associates 1988). Installation of ground- in 2010, for a total of 1.5 million units 92-ton system source heat pump systems requires skills in 2010. Bixby, OK beyond those of most HVAC or plumb- In Europe, the estimated total number of Buckeye Power ing contractors. Until recently, only a installed ground-source heat pumps at 58-ton system small number of contractors have per- the end of 1998 was 100,000 to 120,000. Columbus, OH formed enough installations to develop Nearly 10,000 ground-source heat pumps an extensive base of experience and Fort Polk have been installed in U.S. Federal build- expertise in ground-source heat pumps. several facilities ings, over 400 schools, and thousands of several sizes low-income houses and apartments. The Technology’s Development Ft. Polk, LA A government-industry-utility The ground-source heat pump technol- Frank Knox School consortium (Geothermal Heat Pump ogy has been shown through laboratory 114-ton system Consortium, Inc.) was formed in 1994 testing, field testing, and theoretical Patuxent River Naval Air Station, MD analysis to be technically valid and eco- to create a self-sustaining ground source nomically attractive in many applica- heat pump market. The consortium con- Oklahoma State Capitol tions. Energy savings have been verified sists of the U.S. Department of Energy 855-ton system in a large number of field tests over the (DOE), the U.S. Environmental Protec- Oklahoma City, OK tion Agency (EPA), the Edison Electric past 30 years. In several installations, Public School System Institute (EEI), the National Rural Electric reductions in maintenance costs have 50 schools Cooperative Association, the Consortium also been verified. The technology has Austin, TX gained rapid acceptance from users. for Energy Efficiency, electric utility com- panies, and most ground-source heat Department of HUD The remaining barriers to rapid imple- pump manufacturers. The goal of the Apartment Complex mentation include (1) acceptance from consortium is to reach annual sales of 540-ton system new users and engineers unfamiliar with 400,000 ground-source heat pumps by Stockton State College the technology, (2) out-of-date cost esti- the year 2005. mating guides for construction and 1,655-ton system maintenance, (3) general lack of engi- The GSHP technology-specific Super Pomona, NJ ESPC allows Federal facilities to use neers able to design GSHP systems, and Paint Lick Elementary School private financing. (4) lack of contractors to install and service 123-ton system GSHP systems. This Federal Technology Garrard County, KY Alert is intended to address some of these Manufacturers Salem Community College concerns by reporting on the collective There are a number of manufacturers of 2-80-ton systems experience of ground-source heat pump ground-source heat pumps and water- users and evaluators and by providing source heat pump that can be ground Carney’s Point, NJ application guidance. For actual design coupled. Appendix D contains a list of Love County Hospital guidance, readers should refer to any of U.S. manufacturers provided by the 41-ton system the many publications available, some Geothermal Heat Pump Consortium. Marietta, OK of which are listed at the end of this Bachelor Enlisted Quarters Federal Technology Alert. Who is Using the Technology 25-ton system The list below identifes several Federal Marine Corps Air Station, NC Technology Outlook and private-sector contacts, agencies, The outlook for ground-source heat and locations that already have ground- Life Care Facility pumps is bright. In 1999, an estimated source heat pumps installed and operat- 840-ton system 400,000 ground-source heat pumps were ing. While not inclusive of all applications, Byrn Mawr, PA operating in residential and commercial it does provide a representative sample Yakima County Jail applications, up from 100,000 in 1990. In of the wide variety of existing GSHP 300-ton system 1985, it was estimated that only around projects. Many of the Federal energy Yakima, WA 14,000 ground-source heat pump sys- managers are knowledgeable about tems were installed in the United States. ground-source heat pumps. The reader Lake City High School Annual sales of approximately 45,000 is invited to ask questions and learn 503-ton system units were reported in 1997. With a more about the technology. Couer d’Alene, ID projected annual growth rate of 10%,

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For Further Information “The Source,” International Ground Design and Installation Guides Source Heat Pump Association, pub- *ASHRAE. 1995. “Chapter 29: Geother- Trade Associations lished quarterly and distributed by mal Energy.” ASHRAE Handbook: Electric Power Research Institute (EPRI) Oklahoma State University Ground Heating, Ventilating, and Air-Condi- P.O. Box 50490 Source Heat Pump Publications, tioning Applications. American Society 3412 Hillview Ave. Stillwater, Oklahoma. of Heating, Refrigerating, and Air- Palo Alto, CA 94303 “Geo-Heat Center Quarterly Bulletin,” Conditioning Engineers, Inc. Atlanta, www.epri.com Geo-Heat Center, published quarterly Georgia. Geothermal Heat Pump and distributed by Geo-Heat Center, Bose, J.E., J.D. Parker, and F.C. Consortium, Inc. Oregon Institute of Technology. McQuiston. 1985. Design/Data Manual Washington, D.C. “Down to Earth,” published by the for Closed-Loop Ground-Coupled Heat (202) 508-5222 Fax Michigan Pump Systems. American Society of www.ghpc.org Association. Heating, Refrigerating, and Air- Conditioning Engineers, Inc., Atlanta. Geothermal Resource Council “Outside the Loop”, published quar- P.O. Box 1350 terly by the University of Alabama, Caneta Research, Inc. 1995. Davis, CA 95617 Tuscaloosa, Alabama (www.oit.edu/ Commercial/Institutional Ground- www.geothermal.org ~geoheat/otl/index.htm). Source Heat Pump Engineering International Ground-Source Heat Manual. American Society of Heating, Pump Association (IGSHPA) User and Third-Party Field and Lab Test Refrigerating, and Air-Conditioning Reports 498 Cordell South Engineers, Inc., Atlanta. Oklahoma State University Collie, M.J. (editor) 1979. “Comparison *International Ground-Source Heat Stillwater, OK 74078 of Water-Source and Air-Source Heat Pump Association (not dated). Ground (800) 626-4747 Pumps in Northern Environment,” a Source Systems: Design and Installation (405) 744-5283 Fax chapter in Heat Pump Technology for Standards. Oklahoma State University, www.igshpa.okstate.edu Saving Energy. Noyes Data Corporation, Stillwater. Park Ridge, New Jersey. National Rural Electric Cooperative *Oklahoma State University. 1988. Association (NRECA) Phetteplace, G., H. Ueda, and D. Carbee. Closed-Loop/Ground-Source Heat 1800 Massachusetts Ave., NW 1992. “Performance of Ground-Coupled Pump Systems: Installation Guide. Washington, D.C. 20036 Heat Pumps in Military Family Housing International Ground-Source Heat www.nreca.org Units.” Solar Engineering. G0656A- Pump Association, Stillwater, 1992, American Society of Mechnical National Ground Water Association Oklahoma. Engineers. 601 Dempsey Road *STS Consultants. 1989. Soil and Rock Westerville, OH 43801 Phetteplace, G. 1995. Ground-Coupled Classification for the Design of Ground- (800) 551-7379 Heat Pumps for Family Housing Units. Coupled Heat Pump Systems: Field www.ngwa.org FEAP-UG-CRREL-95/01, U.S. Army Manual. CU-6600, Electric Power Center for Public Works, Alexandria, Michigan Geothermal Energy Research Institute, Palo Alto, California. Virginia. Association *WaterFurnace. October 1991. Polyeth- Lansing, MI *Hughes, P.J. and J.A. Shonder. 1998. ylene Pond/Lake Loop, Mat Design. www.earthcomfort.com “The Evaluation of a 4000-Home WF390, WaterFurnace International, Geothermal Heat Pump Retrofit at Fort Fort Wayne, Indiana. Newsletters Polk, Louisiana: Final Report.” “Heat Pump News Exchange,” Electric ORNL/CON-460, Oak Ridge National Power Research Institute (EPRI), pub- Laboratory, Oak Ridge, Tennessee. lished quarterly and distributed by Svec, O.J. 1987. “Potential of Ground EPRI, Palo Alto, California. Heat Source Systems.” International Journal of Energy Research, Vol. 11, pp. 573-581.

28 FEDERAL ENERGY MANAGEMENT PROGRAM

Manufacturer’s Application Notes Case Studies WaterFurnace. Geothermal comfort Command-Aire. 1988. Earth Energy Duffy, G. March 22, 1993. “120-ton geo- goes low-rise in Kisilano, British Colum- Heat Pumps: Commercial Water Source thermal system replaces 30-year-old bia. Case Study 8, WF923, WaterFurnace Heat Pump Systems; Application, relics.” The , Heating, International, Fort Wayne, Indiana. Installation, Operation Manual. Bulletin and Refrigeration News. WaterFurnace. John Deere dealership C-A10-0191. *Gahran, A. September 1993. “Grants, comforts its clientele from the floor up. Guarino, D.S. March 1993. Util. Rebate Pay 97% of Ground-Source Case Study 11, WF922, WaterFurnace “WaterFurnace: From the Ground Up.” Heat Pump Project Cost.” Energy User International, Fort Wayne, Indiana. Reprint from Contracting Business. News 18(9) pp. 10, 51, 72. WaterFurnace. Last century’s structure *Gahran, A. January 1994. “New retrofitted for the next. Case Study 7, Utility, Information Service, or Government WF924, WaterFurnace International, Agency Tech-Transfer Literature Ground-Source Heat Pumps Cut Energy, Maintenance Costs $68K.” Fort Wayne, Indiana. Bas, E. February 13, 1995. “Geothermal Energy User News 19(1) p. 16. Market Receives Hefty Boost from Con- WaterFurnace. Patients treated to geo- sortium.” The Air Conditioning, Heat- Greenleaf, J. July-September 1982. thermal comfort at Dupont Medical ing, and Refrigeration News, p.1. “College invests in an energy-efficient Center. Case Study 12, WF942, future.” Brown and Caldwell Quarterly. WaterFurnace International, Fort *Calm, J.M. September 1987. Proceed- Wayne, Indiana. ings of the Workshop on Ground-Source KCPL. 1994. A Model of Efficiency from Heat Pumps. From the workshop held the Ground Up. Commerical case study WaterFurnace. Salem Community in Albany, New York, October 27 2M/3-135, Kansas City Power and college enhances environment and through November 1, 1986. HPC-WR-2. Light, Kansas City, Missouri. education. Case Study 4, WF907, International Energy Agency Heat WaterFurnace International, Fort KCPL. 1994. Innovative Heating and Wayne, Indiana. Pump Center. Cooling System Allows Increased Goldfish, L.H., and R.A. Simonelli. 1988. Efficiencies to Surface. Commercial case *WaterFurnace. Three Indiana schools Ground-Source and Hydronic Heat study 4-132, Kansas City Power and compare HVAC notes. Case Study 9, Pump Market Study. EM-6062, Electric Light, Kansas City, Missouri. WF925, WaterFurnace International, Power Research Institute, Palo Alto, Fort Wayne, Indiana. KCPL. 1994. Station’s Ground Source California. Heat Pump System Finds Efficiency in *WaterFurnace. WaterFurnace builds Ground Source Systems: Educational Unusual Places. Commercial case study state-of-the-art facility. Case Study 1, and Marketing Material Catalog. Inter- 4-118, Kansas City Power and Light, WF639, WaterFurnace International, national Ground Source Heat Pump Kansas City, Missouri. Fort Wayne, Indiana. Association, Stillwater, Oklahoma. PSO. “Facility Type: Family Fitness Cen- WaterFurnace. WaterFurnace goes GS-Systems: An Answer to U.S. Energy ter, Technology Application: Ground- down under, down under. Case Study and Environmental Concerns: A com- Source Heat Pump.” Power Profile. 10, WF921, WaterFurnace International, prehensive report on ground-source Number 1, Public Service Company of Fort Wayne, Indiana. heat pumps and their benefits (not Oklahoma, Tulsa, Oklahoma. WaterFurnace. Whitehawk Ranch looks dated). International Ground-Source Randazzo, M. November 1994. earthward for heating and cooling. Case Heat Pump Association, Oklahoma “Retrofit Cut Elec. Use by 32MMkWh/ Study 6, WF916, WaterFurnace Interna- State University, Stillwater. Yr.” Energy User News 19(11) pp. 1,14. tional, Fort Wayne, Indiana. *Pratsch, L.W. 1990. “Geothermal Heat WaterFurnace. Dallas’ “Hope of the WaterFurnace. York County contributes Pumps: A Major Opportunity for the Sun” goes underground for affordable, to a healthier environment. Case Study Utility Industry.” Presented at the efficient, environmental housing. Case 3, WaterFurnace International, Fort Geothermal Energy Conference, Study 5, WF915, WaterFurnace Wayne, Indiana. Columbus, Ohio, November 14, 1990. International, Fort Wayne, Indiana. Scofield, M., and P. Joyner. September *WaterFurnace. Elementary school 1991. “Heat Pumps for Northern Cli- teaches lesson in efficiency. Case Study mates.” EPRI Journal 16(6), pp. 28-33. 2, WF666, WaterFurnace International, Fort Wayne, Indiana.

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Codes and Standards *Geothermal Heat Pumps.” February *Nemeth, R.J., D.E. Fornier, and L.A. *Energy-Efficient Design of New 1990. Custom Builder. 5(2) pp. 32-35. Edgar. 1993. Renewables and Energy- Efficiency Planning. U.S. Army Buildings Except Low-Rise Residential *Giddings, T. February 1988. “Ground Construction Engineering Research Buildings. 1999. ASHRAE/IESNA Water Heat Pumps: Why Doesn’t Every- Laboratory, Champaign, Illinois. Standard 90.1-1999, American Society body Want One?” Well Water Journal of Heating, Refrigerating, and Air- 42(2) pp. 32-33. Oak Ridge National Laboratory (not Conditioning Engineers, Inc., Atlanta. dated). “Big Savings from the World’s Gilmore, V.E. June 1988. “Neo-geo heat Largest Installation of Geothermal Heat *Ground Source Closed-Loop Heat pump.” Popular Science 232(6) pp. 88- Pumps at Fort Polk, Louisiana.” Pumps. 1990. ANSI/ARI Standard 330- 89,112. 90, Air-Conditioning and Refrigeration Oak Ridge National Laboratory, Institute, Inc., Arlington, Virginia. *Heinonen, E.W., Tapscott, R.E., Wildin, Oak Ridge, Tennessee. M.W., and Beall, A.N. February 1997. Outside the Loop. 1999. “Impact of *Ground Water-Source Heat Pumps. “Assessment of Antifreeze Solutions for Conductivity Error on Design Results.” 1985. ARI Standard 325-85. Air- Ground-Source Heat Pump Systems.” Outside the Loop - Volume 2, Number 3, Conditioning and Refrigeration Report 908RP, American Society of University of Alabama, Tuscaloose. Institute, Inc., Arlington, Virginia. Heating, Refrigerating, and Air- *Water-Source Heat Pumps. 1986. Conditioning Engineers (ASHRAE), Phetteplace, G. and S. Kavanaugh ANSI/ARI Standard 320-86. Air- Atlanta. (not dated). “Design Issues for Commercial-Scale Ground-Source Conditioning and Refrigeration Hurlburt, S. February 1988. “Ground Heat Pump Systems.” Institute, Inc., Arlington, Virginia. Water Heat Pumps - The Second Wave.” Well Water Journal 42(2) pp. 34-40. Phetteplace, G., H. Ueda, and D. Carbee. Other References April 1992. Performance of Ground- Kavanaugh, S., C Gilbreath, J. American Society of Heating, Refriger- Coupled Heat Pumps in Military Family Kilpatrick. 1995. Cost Containment for ating, and Air-Conditioning Engineers Housing Units. Proceedings of the 1992 Ground-Source Heat Pumps, Final (ASHRAE). 1997. Ground Source Heat ASME International Solar Energy Report. University of Alabama, Pumps — Design of Geothermal Sys- Conference. Maui, Hawaii, 4-8 April, Tuscaloose. tems for Commercial and Institutional 1992, pp. 377-383. Buildings. ASHRAE, Atlanta. Kavannaugh, S. September 1992. Reynolds, William C., and Herry C. “Ground-coupled heat pumps for Cane, D., A. Morrison, and C. Ireland. Perkins. 1977. Engineering Thermody- commercial buildings.” ASHRAE 1998. Maintenance and Service Costs of namics, pp. 287-289. McGraw-Hill Book Journal 34(9), 30-37. Commercial Building Ground-Source Co., New York. Heat Pump Systems. ASHRAE *Lund, J.W. and T. L. Boyd. 2000. Geo- Rybach, L., and B. Sanner. March 2000. Transactions, Vol 104(2): 699-706. thermal Direct-Use in the United States “Ground-Source Heat Pump Systems in 2000. Geo-Heat Center Quarterly Duffy, G. July/August 1989. “Commer- the European Experience.” Geo-Heat Bulletin, Vol. 21, No. 1 (March), Klamath cial Earth-Coupled Heat Pumps Are Center Quarterly Bulletin 21(1):16-26, Falls, Oregon, pp. 1-5. Ready To Roll.” Engineered Systems, Klamath Falls, Oregon. pp. 40-47. Martin, M.A., D. J. Durfee, and P.J. *Shonder J.A., D. Durfee, M.A. Martin, Hughes. 1999. Comparing Maintenance *Electric Power Research Institure P.J. Hughes, T.R. Sharp. 1999. “Bench- Costs of Geothermal Heat Pump (EPRI). May 1993. 1992 Survey of Utility mark for Performance: Geothermal Systems with Other HVAC Systems in Demand-Side Management Programs. Applications in Lincoln Public Schools.” Lincoln Public Schools: Repair, Service, EPRI-TR 102193, Palo Alto, California. ASHRAE Transactions 105(2): and Corrective Action. ASHRAE 1199-1207. *EPA. 1993. Space Conditioning: Transactions, Vol. 105(2): 1208-1216. The Next Frontier. Office of Air and Shonder, J. A., M. A. Martin, T. R. Sharp, Martin, M.A., M.G. Madgett, and P.J. Radiation, 430-R-93-004 (4/93), EPA, D. J. Durfee, P. J. Hughes. 1999. “Bench- Hughes. 2000. Comparing Maintenance Washington, D.C. mark for Performance: Geothermal Costs of Geothermal Heat Pump Applications in Lincoln Public Schools.” *EPA. 1994. Voluntary Reporting Systems with Other HVAC Systems: ASHRAE SE-99-20-03, Atlanta. Formats for Greenhouse Gas Emissions Preventive Maintenance Actions and and Carbon Sequestration. (Public Total Maintenance Costs. ASHRAE Review Draft, May 1994). EPA, Wash- Transactions, Vol. 106(1): 1-15. ington, D.C.

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Shonder, J. A., V. Baxter, J. Thorton, P. and Borehole Resistance from In Situ *Technical Marketing Associates, Inc. Hughes. June 1999. “A New Compari- Measurements.” ASHRAE Transactions. 1988. Ground-Source and Hydronic son of Vertical Ground Heat Exchanger Heat Pump Market Study. EM-6062, *Spilker, E. H. January 1998. “Ground- Design Methods for Residential Electric Power Research Institute, Palo Coupled Heat Pump Loop Design Applications.” ASHRAE Transactions. Alto, California. Using Thermal Conductivity Testing Shonder, J. A., V. Baxter, P. Hughes, and the Effect of Different Backfill *TM 5-785. 1978. Engineering Weather and J. Thorton (draft - no date). “A Materials on Vertical Bore Length.” Data. Department of the Army Techni- Comparison of Vertical Ground Heat Proceedings of the American Society of cal Manual. TM 5-785, U.S. Government Exchanger Design Software for Heating, Refrigerating, and Air-Condi- Printing Office, Washington, D.C. Commercial Applications.” ASHRAE tioning Engineers (ASHRAE). January Transactions. 1998 meeting, San Francisco, paper SF98-1-3. Shonder, J.A. and J.V. Beck.. 2000. “Field Test of a New Method for Determining Swanson, G.L. August 1986. “Heating Soil Formation Thermal Conductivity and Cooling with GWHPs.” Well Water Journal 40(8) pp. 44-46.

—————————— * Denotes literature cited in the technical body of this Federal Technology Alert.

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Appendixes

Appendix A: Sample Case Spreadsheet Models

Appendix B: Federal Life-Cycle Costing Procedures and the BLCC Software

Appendix C: Performance and Efficiency Terminology Defined

Appendix D: Ground-Source Heat Pump Manufacturers

Appendix E: ARI Rating Conditions

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Appendix A Sample Case Spreadsheet Models

Table A.1. Griffiss AFB Conventional Air-Conditioning and Gas Furnace System Energy Consumption Bin Method Analysis.

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Table A.2. Griffiss AFB Air-Source Heat Pump System Energy Consumption Bin Method Analysis.

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Table A.3. Griffiss AFB Ground-Source Heat Pump System Energy Consumption Bin Method Analysis.

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Table A.4. Summary of Equations for Bin Method Energy Consumption Analysis.

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Table A.5. Oklahoma City Conventional Air-Conditioning and Gas Furnace System Energy Consumption Bin Method Analysis.

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Table A.6. Oklahoma City Air-Source Heat Pump System Energy Consumption Bin Method Analysis.

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Table A.7. Oklahoma City Ground-Source Heat Pump Energy Consumption Bin Method Analysis.

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Appendix B Federal Life-Cycle Costing Procedures and the BLCC Software

Federal agencies are required to evaluate energy-related investments on the basis of minimum life-cycle costs (10 CFR Part 436). A life-cycle cost evaluation computes the total long-run costs of a number of potential actions, and selects the action that mini- mizes the long-run costs. When considering retrofits, sticking with the existing equipment is one potential action, often called the baseline condition. The life-cycle cost (LCC) of a potential investment is the present value of all of the costs associated with the investment over time. The first step in calculating the LCC is the identification of the costs. Installed Cost includes cost of materials purchased and the labor required to install them (for example, the price of an energy-efficient lighting fixture, plus cost of labor to install it). Energy Cost includes annual expenditures on energy to operate equipment. (For example, a lighting fixture that draws 100 watts and operates 2,000 hours annually requires 200,000 watt-hours (200 kWh) annually. At an electricity price of $0.10 per kWh, this fix- ture has an annual energy cost of $20.) Nonfuel Operations and Maintenance includes annual expenditures on parts and activities required to operate equipment (for example, replacing burned out light bulbs). Replacement Costs include expenditures to re- place equipment upon failure (for example, replacing an oil furnace when it is no longer usable). Because LCC includes the cost of money, periodic and aperiodic maintenance (O&M) and equipment replacement costs, energy escalation rates, and salvage value, it is usually expressed as a present value, which is evaluated by LCC = PV(IC) + PV(EC) + PV(OM) + PV(REP) where PV(x) denotes “present value of cost stream x,” IC is the installed cost, EC is the annual energy cost, OM is the annual nonenergy O&M cost, and REP is the future replacement cost. Net present value (NPV) is the difference between the LCCs of two investment alternatives, e.g., the LCC of an energy-saving or energy-cost-reducing alternative and the LCC of the existing, or baseline, equipment. If the alternative’s LCC is less than the baseline’s LCC, the alternative is said to have a positive NPV, i.e., it is cost-effective. NPV is thus given by

NPV = PV(EC0) - PV(EC1)) + PV(OM0) - PV(OM1)) + PV(REP0) - PV(REP1)) - PV(IC) or NPV = PV(ECS) + PV(OMS) + PV(REPS) - PV(IC) where subscript 0 denotes the existing or baseline condition, subscript 1 denotes the energy cost saving measure, IC is the installation cost of the alternative (note that the IC of the baseline is assumed zero), ECS is the annual energy cost savings, OMS is the annual nonenergy O&M savings, and REPS is the future replacement savings. Levelized energy cost (LEC) is the breakeven energy price (blended) at which a conservation, efficiency, renewable, or fuel- switching measure becomes cost-effective (NPV >= 0). Thus, a project’s LEC is given by PV(LEC*EUS) = PV(OMS) + PV(REPS) - PV(IC) where EUS is the annual energy use savings (energy units/yr). Savings-to-investment ratio (SIR) is the total (PV) savings of a measure divided by its installation cost: SIR = (PV(ECS) + PV(OMS) + PV(REPS))/PV(IC). Some of the tedious effort of life-cycle cost calculations can be avoided by using the Building Life-Cycle Cost software, BLCC, developed by NIST. For copies of BLCC, call the FEMP Help Desk at (800) 363-3732. 40 FEDERAL ENERGY MANAGEMENT PROGRAM

Appendix C Performance and Efficiency Terminology Defined

There are many terms used in the heating, air-conditioning, and refrigeration industry that convey performance and efficiency. Many of these terms are synonymous, others are not. When comparing various systems, it is important to understand what the assorted terms are, how they are determined, and their relationship. The following provides a brief description of many (but not all) of the terms used to convey efficiency. Use of the terms is also summarized in Table C.1. Annual Fuel Utilization Efficiency (AFUE): For fuel-fired systems such as boilers and furnaces, AFUE is defined as the ratio of annual output energy to annual input energy. This term is generally applied to systems <=300,000 Btu/h input. AFUE is a weighted average efficiency under standard rated conditions at various part-load conditions and also includes any non-heat- ing-season pilot input losses. AFUE is a unitless term generally expressed as a percentage. Coefficient of Performance (COP): The COP is the basic parameter used to report the efficiency of refrigerant-based systems. It is a unitless term. This term is universal in its use but not in its meaning. COP can be used to define both cooling efficiency or heating efficiency, such as for a heat pump. For cooling, COP is defined as the ratio of the rate of heat removal to the rate of energy input to the compressor, in consistent units. For heating, COP is defined as the ratio of rate of heat delivered to the rate of energy input to the compressor, in consistent units. COP can be used to define the efficiency at a single (standard or non- standard) rated condition or a weighted average (seasonal) condition. Depending on its use, the term may or may not include the energy consumption of auxiliary systems such as indoor or outdoor fans, pumps, or cooling tower systems. For purposes of comparison, the higher the COP the more efficient the system. For mathematical purposes, COP can be treated as an efficiency. (COP of 2.00 = 200% efficient) For unitary heat pumps, ratings at two standard (outdoor) temperatures (47°F and 17°F [8.3°C and -8.3°C]) are typically reported.

Combustion Efficiency (nc or Ec): For fuel-fired systems, this efficiency term is defined as the ratio of the fuel energy input minus the gas losses (dry flue gas, incomplete combustion and moisture formed by combustion of hydrogen) to the fuel energy input. In the U.S., fuel-fired efficiencies are reported based on the higher heating value of the fuel. Other countries report fuel-fired efficiencies based on the lower heating value of the fuel. The combustion efficiency is calculated by determining the fuel gas losses as a percent of fuel burned. [Ec = 1 - flue gas losses] Energy Efficiency Ratio (EER): The EER is a term generally used to define the cooling efficiency of unitary air-conditioning and heat pump systems. The term implies that the efficiency is determined at a single rated condition specified by the appropriate equipment standard and is defined as the ratio of net cooling capacity (heat removed in Btu/h) to the total input rate of electric energy required (watt). The units of EER are Btu/w-h. It is important to note that this efficiency term typically includes the energy requirement of auxiliary systems such as the indoor and outdoor fans. For purposes of comparison, the higher the EER the more efficient the system. To convert to a COP, divide the EER by 3.412. [COP = EER/3.412] Heating Seasonal Performance Factor (HSPF): The term HSPF is similar to the term SEER, except it is used to signify the seasonal heating efficiency of heat pumps. The HSPF is a weighted average efficiency over a range of outside air conditions following a specific standard test method. The term is generally applied to heat pump systems less than 60,000 Btu/h (rated cooling capacity.) The units of HSPF are Btu/w-h. It is important to note that this efficiency term typically includes the energy requirement of auxiliary systems such as the indoor and outdoor fans. For purposes of comparison, the higher the HSPF the more efficient the system. Integrated Part-Load Value (IPLV): The term IPLV is used to signify the cooling efficiency related to a typical (hypothetical) season rather than a single rated condition. The IPLV is calculated by determining the weighted average efficiency at part-load capacities specified by an accepted standard. It is also important to note that IPLVs are typically calculated using the same condensing temperature for each part-load condition and IPLVs do not include cycling or load/unload losses. The units of IPLV are not consistent in the literature; therefore, it is important to confirm which units are implied when the term IPLV is used. ASHRAE Standard 90.1 (using ARI reference standards) uses the term IPLV to report seasonal cooling efficiencies for both seasonal COPs (unitless) and seasonal EERs (Btu/w·h), depending on the equipment capacity category; and most manufacturers report seasonal efficiencies for large as IPLV using units of kW/ton. Depending on how a cooling system loads and unloads (or cycles), the IPLV can be between 5 and 50% higher than the EER at the standard rated condition.

41 FEDERAL ENERGY MANAGEMENT PROGRAM

kW/ton: The term kW/ton is generally used for large commercial and industrial air-conditioning, heat pump, and refrigeration systems. The term is defined as the ratio of the rate of energy consumption (kW) to the rate of heat removal (ton) at a rated con- dition. As the term suggests, the units are kW/ton. Because refrigeration systems of this capacity are typically custom designed, the reported kW/ton generally implies only the compressor and does not include the auxiliaries. However, for specific refer- ences, auxiliaries can be added to report the overall system efficiency using this term. It is important to note that this term is in- verse to the other performance and efficiency terminology. Therefore, for purposes of comparison, the lower the kW/ton the more efficient the system. To convert to a COP, divide 12,000 by the product of 3,412 multiplied by the kW/ton. [COP = 12,000/ (3,412 (kW/ton)] Seasonal Energy Efficiency Ratio (SEER): The term SEER is used to define the average annual cooling efficiency of an air- conditioning or heat pump system. The term SEER is similar to the term EER but is related to a typical (hypothetical) season rather than for a single rated condition. The SEER is a weighted average of EERs over a range of rated outside air conditions following a specific standard test method. The term is generally applied to systems less than 60,000 Btu/h. The units of SEER are Btu/W·h. It is important to note that this efficiency term typically includes the energy requirements of auxiliary systems such as the indoor and outdoor fans. For purposes of comparison, the higher the SEER the more efficient the system. Although SEERs and EERs cannot be directly compared, the SEERs usually range from 0.5 to 1.0 higher than corresponding EERs. Thermal Efficiency (nt or Et): This efficiency term is generally defined as the ratio of the heat absorbed by the water (or the water and steam) to the heat value of the energy consumed. The combustion efficiency of a fuel-fired system will be higher than its thermal efficiency. See ASME Power Test Code 4.1 for more details on determining the thermal efficiency of boilers and other fuel-fired systems. In the U.S., fuel-fired efficiencies are typically reported based on the higher heating value of the fuel. Other countries typically report fuel-fired efficiencies based on the fuel’s lower heating value. The difference between a fuel’s higher heating value and its lower heating value is the latent energy contained in the water vapor (in the exhaust gas) which results when hydrogen (from the fuel) is burned. The efficiency of a system based on a fuel’s lower heating value can be 10 to 15% higher than its efficiency based on a fuel’s higher heating value.

Table C.1. Summary of Performance and Efficiency Terminology.

Operating Mode Design Rated Conditions Seasonal Average Conditions Cooling COP COP EER IPL kW/ton SEER Heating COP AFUE

Ec COP Et HSPF

42 FEDERAL ENERGY MANAGEMENT PROGRAM

Appendix D Ground-Source Heat Pump Manufacturers

Addison Products Company DeMarco Energy Systems Mammoth, Inc. Mr. Dave Phillips of America, Inc. Mr. Craig Fischbach 7050 Overland Road Mr. Victor DeMarco 101 West 82nd Street Orlando, FL 32810 P.O. Box 201057 Chaska, MN 55318 Tel. 407-292-4400 Austin, TX 78720 Tel: (612) 361-2644 Fax 407-290-1329 Tel: (512) 335-1494 Fax: (612) 361-2700 www.addison-hvac.com Fax: (512) 335-6380 E-Mail: [email protected] www.demarcoenergy.com http://www.mammoth-inc.com Advanced Geothermal Technologies Mr. Don Creyts Econar Energy Systems Corp. McQuay International P.O. Box 511 Ms. Susie Overholser Ms. Marilyn Linette Reading, PA 19607 19230 Evans Street 13600 Industrial Park Blvd. Tel: (610) 796-1450 Elk River, MN 55330 P.O. Box 1551 Fax: (610) 796-2070 Tel: (612) 241-3110 Minneapolis, MN 55440 Tel: (800) 4-ECONAR Tel: (612) 553-5168 American Geothermal, Inc. Fax: (612) 241-3111 Fax: (612) 553-5177 Mr. Chris Pamplin www.econar.com http://www.mcquay.com 1037 Old Salem Road Murfreesboro, TN 37129 ECR Technologies Millbrook Industries - Hydronic Division Tel: (615) 890-6985 Mr. Joe Parsons, Jr. Mr. Michael Waldner Tel: (800) 776-8039 3536 DMG Drive RR #3, Box 265 Fax: (615) 890-6926 Lakeland, FL 33811 Mitchell, SD 57301 www.amgeo.com Tel: (863) 701-0096 Tel: (605) 995-0241 Fax: (863) 701-7796 Fax: (605) 996-9186 American Thru Wall E-mail: [email protected] Manufacturing Corp. The Trane Company Mr. Richard W. Wright FHP Manufacturing Mr. Robert Kim or Mr. Howard Newton 59 BC Remington Blvd. Mr. Chris E. Smith 182 Cotton Belt Parkway Ronkonkoma, NY 11779 601 NW 65th Court McGregor, TX 76657 Tel 516-467-5252 Ft. Lauderdale, FL 33309 Tel: (254) 299-6329 Fax 516-467-3452 Tel: (954) 776-5471 Fax: (817) 299-6671 Fax: (954) 776-5529 http://www.trane.com Aqua Cal http://www.fhp-mfg.com 2737 24th Street North WaterFurnace International St. Petersburg, FL 33713 HydroDelta Corportation Mr. Tony Cooper Tel. 813-823-5642 Mr. Tim Burke 9000 Conservation Way Fax 813-821-7471 10205 Gravois Fort Wayne, IN 46809 St. Louis, MO 63123 Tel: (219) 478-5667 Carrier Corporation Tel: (314) 849-5550 Tel: (800) 222-5667 Mr. Chuck Perry Fax: (314) 849-8410 Fax: (219) 478-3029 6752 Melrose Lane E-mail: [email protected] http://www.waterfurnace.com Oklahoma City, OK 73127 Tel: (405) 789-2699 Hydro-Temp Corporation Fax: (405) 789-8755 Mr. Steve Hudson ————————— http://www.carrier.com P.O. Box 566 Copyright (c) 1999 Geothermal Heat Pocahontas, AR 72455 Pump Consortium, Inc. ClimateMaster Tel: (870) 892-8343 Mr. Dan Ellis Tel: (800) 382-3113 7300 SW 44th Street Fax: (870) 892-8323 P.O. Box 25788 http://www.hydro-temp.com Oklahoma City, OK 73125 Tel: (405) 745-6000 Fax: (405) 745-3629 www.climatemaster.com

43 FEDERAL ENERGY MANAGEMENT PROGRAM

Appendix E ARI Rating Conditions

When comparing the efficiency of various equipment, it is important to make an appropriate comparison. The efficiency of any heating or cooling equipment varies with application, load, and related heat-source and heat-sink temperatures. As noted in the beginning of this Federal Technology Alert, most ground-source heat pumps are specific applications of water-source heat pumps. There are three accepted standards for testing heat pump efficiency; these are briefly identified below. Note that the difference among these standards is in application, not necessarily the equipment. Furthermore, standard ratings are for specific temperatures and operating conditions. Standard ratings do not necessarily reflect the efficiency of systems un- der true seasonal operating conditions. In determining the efficiency of heating or cooling equipment for the purpose of estimat- ing energy consumption or potential energy savings, the efficiency should be corrected for the appropriate operating conditions. ARI Standard 320 - Water-Source Heat Pumps. This standard applies to electrically driven mechanical-compression residen- tial, commercial, and industrial water-source heat pumps. Heat pumps rated under this standard are tested under the following standard rating temperatures:

(a) ° ° ° ° (b) ° ° • Cooling: Indoor entering air conditions 80 Fdb (26.7 Cdb) and 67 Fwb (19.4 Cwb). Entering water temperature 85 F (29.4 C). Leaving water temperature 95°F (35.0°C). ° ° ° ° ° • Heating: Indoor entering air conditions 70 Fdb (21.1 Cdb) and 60 Fwb, max (15.6 Cwb, max). Entering water temperature 70 F (21.1°C). Water flow rate same as standard rating cooling test. ARI Standard 325 - Ground Water-Source Heat Pumps. This standard applies to electrically driven mechanical-compression residential, commercial and industrial water-source heat pumps. Heat pumps rated under this standard are tested under the following standard rating temperatures: ° ° ° ° • Cooling (high-temperature): Indoor entering air conditions 80 Fdb (26.7 Cdb) and 67 Fwb (19.4 Cwb). Entering water tempera- ture 70°F (21.1°C). Water flow rate as specified by manufacturer. ° ° ° ° • Cooling (low-temperature): Indoor entering air conditions 80 Fdb (26.7 Cdb) and 67 Fwb (19.4 Cwb). Entering water tempera- ture 50°F (10.0°C). Water flow rate as specified by manufacturer. ° ° ° ° • Heating (high-temperature): Indoor entering air conditions 70 Fdb (21.1 Cdb) and 60 Fwb, max (15.6 Cwb, max). Entering water temperature 70°F (21.1°C). Water flow rate as specified by manufacturer. ° ° ° ° • Heating (low-temperature): Indoor entering air conditions 70 Fdb (21.1 Cdb) and 60 Fwb, max (15.6 Cwb, max). Entering water temperature 50°F (21.1°C). Water flow rate as specified by manufacturer. ARI Standard 330 - Ground-Source Closed-Loop Heat Pumps. This standard applies to electrically driven mechanical-com- pression residential, commercial, and industrial water-source heat pumps. Heat pumps rated under this standard are tested un- der the following Standard Rating Temperatures (the fluid for the test is based on a 15% solution by weight of sodium chloride and water): ° ° ° ° ° ° • Cooling: Indoor entering air conditions 80 Fdb (26.7 Cdb) and 67 Fwb (19.4 Cwb). Entering fluid temperature 77 F (25.0 C). Fluid flow rate as specified by manufacturer. ° ° ° ° ° • Heating: Indoor entering air conditions 70 Fdb (21.1 Cdb) and 60 Fwb, max (15.6 Cwb, max). Entering fluid temperature 32 F (0.0°C). Fluid flow rate same as standard rating cooling test.

(a) This is the ventilation air entering the indoor coil to be conditioned. (b) This is the water entering the heat pump from the ground-coupling or boiler/tower system.

44 FEDERAL ENERGY MANAGEMENT PROGRAM

About FEMP 's New Technology Demonstration Program

The Energy Policy Act of 1992, and sub- Technology Installation Reviews— of its screening tests; a description of sequent Executive Orders, mandate that concise reports describing a new tech- its performance, applications and field energy consumption in Federal build- nology and providing case study results, experience to date; a list of manufactur- ings be reduced by 35% from 1985 levels typically from another demonstration ers; and important contact information. by the year 2010. To achieve this goal, program or pilot project. Attached appendixes provide supple- the U.S. Department of Energy’s Federal mental information and example work- Technology Focuses—brief information Energy Management Program (FEMP) sheets on the technology. on new, energy-efficient, environmen- is sponsoring a series of programs to tally friendly technologies of potential FEMP sponsors publication of the Federal reduce energy consumption at Federal interest to the Federal sector. Technology Alerts to facilitate information- installations nationwide. One of these sharing between manufacturers and gov- programs, the New Technology Demon- More on Federal Technology Alerts ernment staff. While the technology stration Program (NTDP), is tasked to featured promises significant Federal accelerate the introduction of energy- Federal Technology Alerts, our signature sector savings, the Federal Technology efficient and renewable technologies reports, provide summary information Alerts do not constitute FEMP’s endorse- into the Federal sector and to improve on candidate energy-saving technolo- ment of a particular product, as FEMP the rate of technology transfer. gies developed and manufactured in the United States. The technologies featured has not independently verified perfor- As part of this effort FEMP is sponsor- in the Federal Technology Alerts have mance data provided by manufacturers. ing a series of publications that are already entered the market and have Furthermore, the Federal Technology designed to disseminate information some experience but are not in general Alerts do not attempt to chart market ac- on new and emerging technologies. use in the Federal sector. tivity vis-a-vis the technology featured. New Technology Demonstration Readers should note the publication date Program publications comprise three The goal of the Federal Technology Alerts on the back cover, and consider the Fed- separate series: is to improve the rate of technology trans- eral Technology Alerts as an accurate fer of new energy-saving technologies picture of the technology and its perfor- Federal Technology Alerts—longer within the Federal sector and to provide mance at the time of publication. Product summary reports that provide details the right people in the field with accurate, innovations and the entrance of new on energy-efficient, water-conserving, up-to-date information on the new tech- manufacturers or suppliers should be and renewable-energy technologies nologies so that they can make educated anticipated since the date of publication. that have been selected for further judgments on whether the technologies FEMP encourages interested Federal study for possible implementation in are suitable for their Federal sites. energy and facility managers to contact the Federal sector. Additional informa- the manufacturers and other Federal tion on Federal Technology Alerts is The information in the Federal Technology sites directly, and to use the worksheets provided in the next column. Alerts typically includes a description of the candidate technology; the results in the Federal Technology Alerts to aid in their purchasing decisions.

Federal Energy Management Program The Federal Government is the largest energy consumer in the nation. Annually, in its 500,000 buildings and 8,000 loca- tions worldwide, it uses nearly two quadrillion Btu (quads) of energy, costing over $8 billion. This represents 2.5% of all 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 pro- grams 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; and, most recently, Executive Order 12759 in 1991, the National Energy Policy Act of 1992 (EPACT), Executive Order 12902 in 1994, and Executive Order 13123 in 1999. 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. FEDERAL ENERGY MANAGEMENT PROGRAM For More Information

FEMP Help Desk (800) 363-3732 International callers please use (703) 287-8391 Web site: www.eren.doe.gov/femp

General 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 [email protected]

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 [email protected]

Technical Contacts Donald L. Hadley Pacific Northwest National Log on to FEMP''s New Technology Demonstration Program Laboratory P.O. Box 999, MSIN: K5-16 Website Richland, WA 99352 http://www.eren.doe.gov/femp/prodtech/newtechdemo.html Phone: (509) 375-3708 Fax: (509) 375-3614 [email protected] You will find links to ¥ An overview of the New Technology Demonstration Program Gary Phetteplace U.S. Army Cold Regions Research ¥ Information on the program’s technology demonstrations and Engineering Laboratory 72 Lyme Road ¥ Downloadable versions of program publications in Adobe Hanover, NH 03755 Portable Document Format (PDF) Phone: (603) 646-4248 ¥ A list of new technology projects underway Fax: (603) 646-4380 [email protected] ¥ Electronic access to the program’s regular mailing list for new products when they become available John A. Shonder Oak Ridge National Laboratory ¥ How Federal agencies may submit requests for the program to P.O. Box 2008 MS6070 assess new and emerging technologies Oak Ridge, TN 37831 Phone: (865) 574-2015 Fax: (865) 574-9338 [email protected]

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