This page provides acquisition guidance for buying residential geothermal heat pumps. Federal laws and requirements mandate that agencies purchase ENERGY STAR®-certified products or Federal Energy Management Program (FEMP)-designated products for all covered product categories except as specifically exempted by law.
FEMP's acquisition guidance and associated ENERGY STAR efficiency requirements for geothermal heat pumps applies to open loop, closed loop, and direct geoexchange products that operate on single-phase current. Commercial products (those that operate on three-phase electric current) are excluded.
This acquisition guidance was updated in December 2024.
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How To Find Product Efficiency Requirements
The U.S. Environmental Protection Agency (EPA) provides geothermal heat pump program requirements and efficiency criteria on the ENERGY STAR website. Manufacturers meeting these requirements are allowed to display the ENERGY STAR label on complying models. Federal buyers can use ENERGY STAR's list of certified geothermal heat pumps to identify or verify complying models.
To reflect the influence of climate on heat pump use, EPA specifies efficiency levels for geothermal heat pumps in three regions: Southeast, Southwest, and Northern, which effectively includes all states outside of those with hot/dry or hot/humid climates.
How To Determine Cost Effectiveness
An efficient product is cost effective when the lifetime energy savings exceed the up-front cost premium (if any) compared to a less efficient option. You can find more information about determining life cycle cost effectiveness on FEMP’s general federal purchasing requirements webpage.
Federal buyers may find the most relevant guidance in Tables 1-3 below based on the planned location of the installation. Each example compares the life cycle cost savings of a base model (less efficient than the ENERGY STAR required efficiency), a model meeting ENERGY STAR efficiency levels, and a model with the highest available efficiency.
Example 1: Southeast States
FEMP has calculated that the required ENERGY STAR-qualified geothermal heat pump saves money if priced no more than $2,162 (in 2023 dollars) above the less efficient model. The best available model saves up to $6,333 (or $4,171 more than the required model).
Southeast states include Alabama, Arkansas, Delaware, Florida, Georgia, Hawaii, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, Puerto Rico, South Carolina, Tennessee, Texas, Virginia, the District of Columbia, and the U.S. territories.
Table 1. Lifetime Savings for Efficient Geothermal Heat Pumps in Southeast States
| Performance | Best Available | ENERGY STAR | Less Efficient |
|---|---|---|---|
| EER/COP | 26.1/4.8 | 17.1/3.6 | 15.0/3.1 |
| Annual Energy Use: Heating and Cooling (kWh) | 5,740 kWh | 8,117 kWh | 9,348 kWh |
| Annual Energy Cost: Heating and Cooling ($) | $632 | $893 | $1,029 |
| Lifetime Energy Cost (15 years) | $10,078 | $14,250 | $16,412 |
| Lifetime Energy Cost Savings | $6,333 | $2,162 | ====== |
Energy Use and Cost Assumptions
Energy Efficiency Ratio (EER): Shown in British thermal units per watt-hour (Btu/Wh).
Coefficient of performance: A unitless ratio of total heating energy output and the electrical energy input to the geothermal heat pump.
Annual Energy Use: Based on the test method referenced in ISO 13256-1:1998 “Water-source heat pumps — Testing and rating for performance.” The example refers to a 36,000 Btu/h residential geothermal heat pump operating in El Dorado, Arkansas, as a representative example for estimating savings in southeast states. The estimated operating hours are 1,738 hours for cooling mode and 1,521 hours for heating mode per year as seen in the Arkansas Technical Reference Manual Version 9.1.
Annual Energy Cost: Calculated based on an assumed electricity price of 11¢/kWh, which is the average electricity price at federal facilities throughout the United States as of July 2024. Learn more about Federal Government Energy/Water Use and Emissions data.
Lifetime Energy Cost: The sum of the discounted values of annual energy cost with an average residential air-source heat pump life of 15 years. Future electricity price trends and a 3% discount rate are from Annual Supplement to NIST Handbook 135, Energy Price Indices and Discount Factors for Life Cycle Cost Analysis – 2024 (NISTIR 85-3273-39).
Lifetime Energy Cost Savings: The difference between the lifetime energy cost of the identified models.
Model Efficiency Levels
Best Available: Based on the model with the highest efficiency in the ENERGY STAR Qualified Products List as of December 2024. More efficient models may have entered the market after FEMP's acquisition guidance was created.
ENERGY STAR: Calculated based on December 2024 ENERGY STAR efficiency levels; values shown are rounded to the nearest dollar. Federal agencies must purchase products that meet or exceed ENERGY STAR efficiency levels.
Less Efficient: Calculated based on typical products used in non-federal applications.
Example 2: Southwest States
FEMP has calculated that the required ENERGY STAR-qualified geothermal heat pump saves money if priced no more than $842 (in 2023 dollars) above the less efficient model. The best available model saves up to $2,658 (or $1,816 more than the required model).
Southwest states include Arizona, California, Nevada, and New Mexico.
Table 2. Lifetime Savings for Efficient Geothermal Heat Pumps in Southwest States
| Performance | Best Available | ENERGY STAR | Less Efficient |
|---|---|---|---|
| EER/COP | 26.1/4.8 | 17.1/3.6 | 15.0/3.1 |
| Annual Energy Use: Heating and Cooling (kWh) | 2,239 kWh | 3,274 kWh | 3,753 kWh |
| Annual Energy Cost: Heating and Cooling ($) | $246 | $360 | $413 |
| Lifetime Energy Cost (15 years) | $3,931 | $5,747 | $6,589 |
| Lifetime Energy Cost Savings | $2,658 | $842 | ====== |
Energy Use and Cost Assumptions
Energy Efficiency Ratio (EER): Shown in British thermal units per watt-hour (Btu/Wh).
Coefficient of performance: A unitless ratio of total heating energy output and the electrical energy input to the geothermal heat pump.
Annual Energy Use: Based on the test method referenced in ISO 13256-1:1998 "Water-source heat pumps — Testing and rating for performance."
The example refers to a 36,000 Btu/h residential geothermal heat pump operating in Albuquerque, New Mexico, as a representative example for estimating savings in southwest states. The estimated operating hours are 1,083 hours for cooling mode and 339 hours for heating mode per year in a small office space as seen in the New Mexico Technical Resource Manual for the Calculation of Energy Efficiency Savings.
Annual Energy Cost: Calculated based on an assumed electricity price of 11¢/kWh, which is the average electricity price at federal facilities throughout the United States as of July 2024. Learn more about Federal Government Energy/Water Use and Emissions data.
Lifetime Energy Cost: The sum of the discounted values of annual energy cost with an average geothermal heat pump life of 15 years. Future electricity price trends and a 3% discount rate are from Annual Supplement to NIST Handbook 135, Energy Price Indices and Discount Factors for Life Cycle Cost Analysis – 2024 (NISTIR 85-3273-39).
Lifetime Energy Cost Savings: The difference between the lifetime energy cost of the identified models.
Model Efficiency Levels
Best Available: Based on the model with the highest efficiency in the ENERGY STAR Qualified Products List as of December 2024. More efficient models may have entered the market after FEMP's acquisition guidance was created.
ENERGY STAR: Calculated based on December 2024 ENERGY STAR efficiency levels; values shown are rounded to the nearest dollar. Federal agencies must purchase products that meet or exceed ENERGY STAR efficiency levels.
Less Efficient: Calculated based on typical products used in non-federal applications.
Example 3: Northern States
FEMP has calculated that the required ENERGY STAR-qualified geothermal heat pump saves money if priced no more than $1,666 (in 2023 dollars) above the less efficient model. The best available model saves up to $4,496 (or $2,830 more than the required model).
Northern states include all states not included in the Southeast and Southwest states categories.
Table 3. Lifetime Savings for Efficient Geothermal Heat Pumps in Northern States
| Performance | Best Available | ENERGY STAR | Less Efficient |
|---|---|---|---|
| EER/COP | 26.1/4.8 | 17.1/3.6 | 15.0/3.1 |
| Annual Energy Use: Heating and Cooling (kWh) | 4,418 kWh | 6,030 kWh | 6,979 kWh |
| Annual Energy Cost: Heating and Cooling ($) | $486 | $664 | $768 |
| Lifetime Energy Cost (15 years) | $7,756 | $10,586 | $12,253 |
| Lifetime Energy Cost Savings | $4,496 | $1,666 | ====== |
Energy Use and Cost Assumptions
Energy Efficiency Ratio (EER): Shown in British thermal units per watt-hour (Btu/Wh).
Coefficient of performance: A unitless ratio of total heating energy output and the electrical energy input to the geothermal heat pump.
Annual Energy Use: Based on the test method referenced in ISO 13256-1:1998 "Water-source heat pumps — Testing and rating for performance."
The example refers to a 36,000 Btu/h residential geothermal heat pump operating in Albany, New York, as a representative example for estimating savings in northern states. The estimated operating hours are 524 hours for cooling mode and 1,681 hours for heating mode per year as seen in the New York Standard Approach for Estimating Energy Savings from Energy Efficiency Programs.
Annual Energy Cost: Calculated based on an assumed electricity price of 11¢/kWh, which is the average electricity price at federal facilities throughout the United States as of July 2024. Learn more about Federal Government Energy/Water Use and Emissions data.
Lifetime Energy Cost: The sum of the discounted values of annual energy cost with an average residential geothermal heat pump life of 15 years. Future electricity price trends and a 3% discount rate are from Annual Supplement to NIST Handbook 135, Energy Price Indices and Discount Factors for Life Cycle Cost Analysis – 2024 (NISTIR 85-3273-39).
Lifetime Energy Cost Savings: The difference between the lifetime energy cost of the identified models.
Model Efficiency Levels
Best Available: Based on the model with the highest efficiency in the ENERGY STAR Qualified Products List as of December 2024. More efficient models may have entered the market after FEMP's acquisition guidance was created.
ENERGY STAR: Calculated based on December 2024 ENERGY STAR efficiency levels; values shown are rounded to the nearest dollar. Federal agencies must purchase products that meet or exceed ENERGY STAR efficiency levels.
Less Efficient: Calculated based on typical products used in non-federal applications.
Where To Buy Compliant Products
Buyers can make sure the product they purchase will be compliant by incorporating federal acquisition regulation language into contracts. Compliant products can also be found using federal supply sources and product codes. See FEMP’s general federal purchasing requirements webpage for more details on buying compliant energy-using products.
Other Tips for Choosing and Using the Best Product Efficiently
There are various types of geothermal heat pumps, including open loop, closed loop, direct geoexchange, and hybrid systems using several different heat sinks/sources. Learn more about the different types of geothermal heat pumps.
A proper assessment of the building's peak heating and cooling loads is critical to the design of a geothermal heat pump system. As with all heating and cooling equipment, oversizing of geothermal heat pumps, besides raising purchase cost, will result in decreased energy efficiency, poorer humidity control, and shorter product life, all due to excessive on-off cycling.
Accurate knowledge of the properties of the geothermal resource is also crucial in the design of a geothermal heat pump system. For ground-coupled systems, important parameters include the thermal conductivity and temperature stability of the soil formation. In larger installations, these properties are often measured directly in short-term tests at one or more locations on the site. Because ground heat exchangers represent a significant portion of the cost of these types of systems, it is important to size ground loops accurately. Software tools for ground loop sizing are available from a number of vendors.
The design of groundwater systems depends on several properties of the water source, including temperature, well flow rates, and water quality. Surface water systems, whether open or closed loop, depend on the temperature profile of the surface water body (through all seasons, as this may vary significantly).
Because geothermal heat pumps may be more costly to purchase than more conventional systems, direct procurement may be problematic. FEMP has a variety of project financing programs that allow federal facilities to leverage available resources with private financing to fund energy conservation measures, including geothermal heat pumps.
Many states and electric utilities offer rebates or other incentives for the purchase of ENERGY STAR-qualified products. Use the ENERGY STAR Rebate Finder to see if your local utility offers these incentives.
When installed, operated and maintained properly, geothermal heat pumps provide years of safe and effective service. Having a trained technician service the heat pump annually is necessary to maintain peak performance.