This page contains acquisition guidance for different chiller types. Each chiller type has unique efficiency requirements based on their cooling medium and capacity. Federal laws and requirements mandate that agencies must specify and purchase ENERGY STAR®-qualified or Federal Energy Management Program (FEMP)-designated products for all covered product categories except as specifically exempted by law. FEMP-designated requirements provide acquisition guidance and an efficiency standard for air-cooled and water-cooled electric chillers. Free-cooling, condenserless, and combination chiller-heat pump units are currently excluded. Other heating, ventilation, and air conditioning (HVAC), refrigeration, heat pump, and cooling products are covered under different product categories.
This acquisition guidance was updated in October 2024.
How To Find Product Efficiency Requirements
The chiller efficiency requirements cover air-cooled and water-cooled electric chillers and take into account whether the chiller will be operated at full or partial load for most of its use. Table 1 below is a guide to where to find the appropriate chiller efficiencies on this page. Federal purchases must meet or exceed the minimum efficiency requirements depending on both the chiller type and intended operation pattern. Product performance must be measured in accordance with Air-Conditioning, Heating, and Refrigeration Institute (AHRI) 550/590 test procedures.
Table 1. Where To Find Efficiency Requirements By Chiller Type and Intended Operation
| Chiller Type | Primary Operation: Full Load | Primary Operation: Partial Load |
|---|---|---|
| Air-Cooled Chillers | Table 2.1 | Table 2.2 |
Water-Cooled Chillers
| Table 3.1 | Table 3.2 |
If the chiller is likely to be operated at full load most of the time, refer to Table 2.1 or Table 3.1 to find the efficiency requirement for full-load-optimized chillers. That chiller also should meet the paired requirement for efficiency in serving partial loads, which is the ASHRAE 90.1-2022 Path A minimum integrated part-load value (IPLV).
If the chiller is expected to be operated primarily at variable loads, refer to Table 2.2 or Table 3.2 to find the efficiency requirement for part-load-optimized chillers. That chiller also should meet the paired requirement for efficiency at full load, which is the ASHRAE 90.1-2022 Path B minimum full-load efficiency.
Air-Cooled Chillers
Federal purchases must meet or exceed the minimum efficiency requirements for air-cooled chillers in either Table 2.1 or Table 2.2. The efficiency requirements differ depending on whether the chiller will primarily be operated in full- or part-load optimized applications.
Full-Load Capacity
Air-cooled chillers that are likely to operate primarily at full-load capacity most of the time must comply with the efficiency requirements in Table 2.1.
Table 2.1 Efficiency Requirements for Full-Load Optimized Air-Cooled Electric Chillers
| Chiller Type | Capacity | Energy Efficiency Ratio [EER], Btu/watt (product must meet both values) | |
|---|---|---|---|
| Full-Load Efficiency | Integrated Part-Load Value (IPLV) | ||
| Air-Cooled, All Compressors | < 150 tons | 10.890 | 13.700 |
| ≥ 150 tons | 10.964 | 14.000 | |
Variable-Load Capacity
Air-cooled chillers that are likely to operate primarily at variable loads most of the time must comply with the efficiency requirements in Table 2.2.
Table 2.2 Efficiency Requirements for Part-Load Optimized Air-Cooled Electric Chillers
| Chiller Type | Capacity | Energy Efficiency Ratio [EER], Btu/watt (product must meet both values) | |
|---|---|---|---|
| Full-Load Efficiency | Integrated Part-Load Value (IPLV) | ||
| Air-Cooled, All Compressors | < 150 tons | 9.700 | 16.860 |
| ≥ 150 tons | 9.700 | 17.300 | |
Water-Cooled Chillers
Federal purchases must meet or exceed the minimum efficiency requirements in either Table 3.1 or 3.2. The efficiency requirements differ by full- and part-load optimized applications.
Full-Load Capacity
Water-cooled chillers that operate primarily at full load capacity must comply with the efficiency requirements in Table 3.1.
Table 3.1 Efficiency Requirements for Full-Load Optimized Water-Cooled Electric Chillers
| Chiller Type | Capacity | Efficiency [kW/ton] (product must meet both values) | |
|---|---|---|---|
| Full-Load Efficiency | Integrated Part-Load Value (IPLV) | ||
| Positive Displacement | < 75 | 0.728 | 0.600 |
| 75 to 149 | 0.701 | 0.560 | |
| 150 to 299 | 0.611 | 0.540 | |
| 300 to 599 | 0.594 | 0.520 | |
| ≥ 600 | 0.560 | 0.500 | |
| Centrifugal | < 150 | 0.610 | 0.550 |
| 150 to 299 | 0.566 | 0.550 | |
| 300 to 399 | 0.544 | 0.520 | |
| 400 to 599 | 0.541 | 0.500 | |
| ≥ 600 | 0.501 | 0.500 | |
Variable-Load Capacity
Water-cooled chillers that operate primarily at partial-load capacity, must comply with the efficiency requirements in Table 3.2.
Table 3.2 Efficiency Requirements for Part-Load Optimized Water-Cooled Electric Chillers
| Chiller Type | Capacity | Efficiency [kW/ton] (product must meet both values) | |
|---|---|---|---|
| Full-Load Efficiency | Integrated Part-Load Value (IPLV) | ||
| Positive Displacement | < 75 | 0.780 | 0.567 |
| 75 to 149 | 0.750 | 0.482 | |
| 150 to 299 | 0.680 | 0.366 | |
| 300 to 599 | 0.625 | 0.352 | |
| ≥ 600 | 0.585 | 0.380 | |
| Centrifugal | < 150 | 0.695 | 0.440 |
| 150 to 299 | 0.635 | 0.380 | |
| 300 to 399 | 0.595 | 0.370 | |
| 400 to 599 | 0.585 | 0.408 | |
| ≥ 600 | 0.585 | 0.400 | |
Why Chillers Must Meet Both Full Load and IPLV Requirements
A chiller can be efficient in both full- and part-load conditions, or it might have a high full- or part-load efficiency at the expense of the other. Federal buyers could purchase a chiller with the intent of operating at part-load, but in reality the chiller could end up operating at full load for a substantial period of time. Conversely, a “full-load optimized” chiller may end up serving part-load applications. To address these situations, FEMP’s efficiency requirements for full load-optimized and part load-optimized applications are each paired to complementary efficiency values for the alternative operating modes based on ASHRAE 90.1 guidance. The two sets of paired requirements are summarized as follows.
Full-load optimized chillers:
- Full load requirement (based on 25th percentile of most efficient products), and
- IPLV requirement (greater than or equal to ASHRAE 90.1-2022 Path A minimum IPLV).
Part-load optimized chillers:
- IPLV requirement (based on 25th percentile of most efficient products), and
- Full load requirement (greater than or equal to ASHRAE 90.1-2022 Path B minimum full load efficiency).
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. Find more information about determining life cycle cost effectiveness on FEMP’s general purchasing requirements webpage.
See the tables below for two examples comparing the life cycle energy cost savings of base models (less efficient than the FEMP-designated efficiency), models meeting the FEMP-designated efficiency, and models with the highest available efficiency. Tables 4 and 5 provide examples for each type of chiller.
Example 1: Air-Cooled Chiller
FEMP has calculated that a 175-ton air-cooled chiller meeting the required 10.964 EER efficiency level saves money if it costs no more than $74,491 more than the less-efficient model with an EER of 9.700. The best available model shown below is cost effective if costs no more than $110,451 above the less efficient model (or $35,960 above the required model).
Table 4. Lifetime Savings for an Efficient 175-Ton Air-Cooled Chiller in a Full-Load Application
| Performance | High Efficiency Model | Required Efficiency Model | Lower Efficiency Model |
|---|---|---|---|
| Full Load Efficiency (EER) | 11.700 | 10.964 | 9.700 |
| Annual Energy Use (kWh) | 358,974 | 383,072 | 432,990 |
| Annual Energy Cost ($/yr) | $35,556 | $37,943 | $42,888 |
| Lifetime Energy Cost (23 years) | $535,689 | $571,649 | $646,140 |
| Lifetime Energy Cost Savings | $110,451 | $74,491 | ==== |
Example 2: Water-Cooled Chiller
FEMP has calculated that a 300-ton air-cooled chiller meeting the required 0.544 kW/ton efficiency level saves money if it costs no more than $128,037 above the less-efficient model. The best available model shown below is cost-effective if it costs no more than $162,957 more than the less efficient model.
Table 5. Lifetime Savings for an Efficient 300-Ton Water-Cooled Centrifugal Chiller in a Full-Load Application
| Performance | High Efficiency Model | Required Efficiency Modela | Lower Efficiency Model |
|---|---|---|---|
| Full Load Efficiency (kW/ton) | 0.505 | 0.544 | 0.687 |
| Annual Energy Use (kWh) | 303,000 | 326,400 | 412,200 |
| Annual Energy Cost ($/yr) | $30,012 | $32,330 | $40,828 |
| Lifetime Energy Cost (23 years) | $452,160 | $487,079 | $615,117 |
| Lifetime Energy Cost Savings | $162,957 | $128,037 | ==== |
a Note: For kilowatts/ton, a lower value is more efficient.
Energy Use and Cost Assumptions
Annual Energy Use: Assumed chillers operate for 2,000 hours per year and have a lifetime of 23 years.
Annual Energy Cost: Calculated based on an energy price of 9.9¢/kWh, which is the average electricity price at federal facilities in the United States as of July 2024.
Lifetime Energy Cost: Used future electricity price trends and a 3% discount rate from the Energy Price Indices and Discount Factors for Life-Cycle Cost Analysis – 2024: Annual Supplement to NIST Handbook 135 and NBS Special Publication 709 (NISTIR 85-3273-39).
Lifetime Energy Cost Savings: The difference between the lifetime energy cost of the identified models.
Model Efficiency Levels
High Efficiency Model: Calculated based on the highest efficiency model identified in publicly provided manufacturer data as of July 2024. Note that more efficient models may be introduced after FEMP's market analysis took place.
Required Efficiency Model: Calculated based on FEMP-designated efficiency requirements. Federal agencies must purchase products that meet or exceed FEMP-designated efficiency levels.
Lower Efficiency Model: Calculated based on a lower efficiency model identified in publicly provided manufacturer data as of July 2024. Note that less efficient models exist in the market.
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.
Electric Chiller Product Codes
The Defense Logistics Agency Environmental Attribute Code (ENAC) identifies items with energy characteristics that meet standards set by an approved third party, such as FEMP and ENERGY STAR. Purchasers can also use a United Nations Standard Products and Services Code (UNSPSC) to identify and buy products and to track purchases.
The UNSPSCs and DLA ENACs for chillers are listed in Table 6.
Table 6. Product Codes for Air- and Water-Cooled Chillers
| Chiller Type | DLA ENAC | UNSPSC |
|---|---|---|
| Air-Cooled Chillers | JS | 40101710 and 40101712 |
| Water-Cooled Chillers | JU | 40101711 |
Other Tips for Choosing the Best Product
Choosing Between Air-Cooled and Water-Cooled Chillers
When deciding on a chilled water system, designers must choose between air- and water-cooled chillers. Air-cooled systems eliminate the need for a cooling tower, reducing installation and maintenance costs. However, air-cooled chillers are substantially less efficient than water-cooled models. To compare air- and water-cooled options, a detailed life cycle cost analysis can be performed using Building Life Cycle Cost (BLCC) software available through FEMP. Buyers are advised to purchase the highest-efficiency chiller estimated to be cost-effective.
Chiller Refrigerant Transition
Refrigerants for chillers fall under EPA's Significant New Alternatives Policy (SNAP) program, which encourages private sector investment in low-emissions technology by identifying and approving climate-friendly chemicals while prohibiting certain uses of the most harmful chemical alternatives. Following the passage of the American Innovation and Manufacturing Act (AIM) and subsequent rulemaking on AIM implementation in 2023, the EPA announced a schedule for HVAC and refrigerant manufacturers to transition to less harmful refrigerants, those with lower global warming potential (GWP). Under this rule, self-contained chiller products that are fully assembled and use high-GWP refrigerants cannot be manufactured after January 1, 2025, and chiller systems relying on high-GWP refrigerants may not be installed after December 31, 2025. Buyers should procure chiller systems with lower-GWP refrigerants wherever possible to avoid unnecessary greenhouse gas emissions from leakage of high-GWP refrigerants, as well as potentially higher installation, maintenance, or retrofit costs as the refrigerant transition takes effect.
Networked Devices
Many new chillers come equipped with Internet of Things (IoT) sensing components and network connectivity. Connected chillers make it much easier to reduce loads on a signal from site management or the utility, enabling greater demand flexibility and reducing energy use.
Making a new chiller purchase or replacement represents a prime opportunity to evaluate the vulnerabilities of your network. All IoT-enabled devices can introduce exposures to potential data breaches. Building controls and heating, ventilating, and air conditioning systems are no exception. Security can almost never be networked in after the fact, and so it is important to ensure that your networked devices are secure. Also, regularly testing for network vulnerabilities is key. For more information on how to build cybersecure networks of building technologies, consult FEMP's Energy and Cybersecurity Integration resources and Cyber-Securing Facility Related Control Systems fact sheet.