The Federal Energy Management Program (FEMP) provides acquisition guidance for water-cooled electric chillers, a product category covered by FEMP efficiency requirements.

FEMP's acquisition guidance and efficiency requirements apply to water-cooled chillers that provide space cooling in federal buildings. Product performance must be measured in accordance with AHRI 550/590 test procedures. Free-cooling, condenserless, and combination chiller-heat pump units are excluded. Air-cooled electric chillers are covered by FEMP efficiency requirements under a separate product category.

This acquisition guidance was updated in September 2022.

Find Product Efficiency Requirements

Federal purchases must meet or exceed the minimum efficiency requirements in Table 1. Note that efficiency requirements differ by full- and part-load optimized applications.

Table 1. Efficiency Requirements for Water-Cooled Electric Chillers (kW/ton)
Chiller Type Capacity (tons) Full-Load Optimized Applications
(products must meet both levels)
Part-Load Optimized Applications
(products must meet both levels)
Full Load Efficiency Integrated Part-Load Value (IPLV) Full Load Efficiency Integrated Part-Load Value (IPLV)
Positive Displacement < 75 0.728 0.600 0.780 0.500
75 to 149 0.714 0.560 0.750 0.490
150 to 299 0.628 0.540 0.680 0.440
300 to 599 0.610 0.520 0.625 0.410
≥ 600 0.560 0.500 0.585 0.380
Centrifugal < 150 0.610 0.550 0.695 0.440
150 to 299 0.544 0.550 0.635 0.380
300 to 399 0.544 0.520 0.595 0.370
400 to 599 0.541 0.500 0.585 0.360
≥ 600 0.520 0.500 0.585 0.325


Make a Cost-Effective Purchase: Reduce Operating Costs by Buying a FEMP-Designated Product

FEMP has calculated that a 500-ton water-cooled centrifugal chiller meeting the required 0.541 kW/ton efficiency level saves money if priced no more than $28,047 above the less efficient model. The best available model saves the average user more: it is cost-effective up to a price premium of $97,498 above the less efficient model. Table 2 compares three types of product purchases and calculates the lifetime cost savings of purchasing efficient models. Federal purchasers can assume products that meet FEMP-designated efficiency requirements are life cycle cost-effective.

Table 2. Lifetime Savings for an Efficient 500-ton Water-Cooled Centrifugal Chiller in a Full-Load Application
Performance Best Available Required Model Less Efficient
Full Load Efficiency (kW/ton) 0.489 0.541 0.562
Annual Energy Use (kWh) 489,000 541,000 562,000
Annual Energy Cost ($/yr) $42,225 $46,715 $48,529
Lifetime Energy Cost (23 years) $653,106 $722,557 $750,604
Lifetime Energy Cost Savings $97,498 $28,047 ---


View the Performance and Model Assumptions for Table 2

Performance Column

Annual Energy Use: Assumed 2,000 operating hours per year for 23 years.

Annual Energy Cost: Calculated based on an assumed electricity price of 8.6¢/kWh, which is the average electricity price at federal facilities in the United States.

Lifetime Energy Cost: Future electricity price trends and a 3% discount rate are from the Annual Supplement to NIST Handbook 135 and NBS Special Publication 709, Energy Price Indices and Discount Factors for Life Cycle Cost Analysis – 2022 (NISTIR 85-3273-37 update 1).

Lifetime Energy Cost Savings: The difference between the lifetime energy cost of the less efficient model and the lifetime energy cost of the required model or best available model.

Best Available Model Column

Calculated based on highest efficiency model identified in publicly provided manufacturer data as of June 2022. More efficient models may be introduced to the market after FEMP's acquisition guidance is posted.

Required Model Column

Calculated based on FEMP-designated efficiency requirements. Federal agencies must purchase products that meet or exceed FEMP-designated efficiency levels.

Less Efficient Model Column

Calculated based on median efficiency of models identified in publicly provided manufacturer data as of June 2022.

Determine When FEMP-Designated Products Are Cost-Effective

An efficient product is cost-effective when the lifetime energy savings (from avoided energy costs over the life of the product, discounted to present value) exceed the additional up-front cost (if any) compared to a less efficient option. FEMP considers up-front costs and lifetime energy savings when setting required efficiency levels. Federal purchasers can assume that products meeting FEMP-designated efficiency requirements are life cycle cost-effective. In high-use applications or when energy rates are above the federal average, purchasers may save more if they specify products that exceed FEMP's efficiency requirements (e.g., the best available model).

Purchasing Requirements

A gavel on top of a stack of papers.

Federal laws and requirements mandate that agencies purchase ENERGY STAR-qualified products or FEMP-designated products in all product categories covered by these programs and in any acquisition actions that are not specifically exempted by law.

These mandatory requirements apply to all forms of procurement, including construction guide and project specifications; renovation, repair, energy service, and operation and maintenance (O&M) contracts; lease agreements; acquisitions made using purchase cards; and solicitations for offers.

FAR Contract Language

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Federal Acquisition Regulation (FAR) Part 23.206 requires agencies to insert the clause at FAR section 52.223-15 into contracts and solicitations that deliver, acquire, furnish, or specify energy-consuming products for use in federal government facilities. 

To comply with FAR requirements, FEMP recommends that agencies incorporate efficiency requirements into technical specifications, the evaluation criteria of solicitations, and the evaluations of solicitation responses

Claim an Exception to Federal Purchasing Requirements

Products meeting FEMP-designated efficiency requirements may not be life cycle cost-effective in certain low-use applications or in locations with very low rates for electricity or natural gas. However, for most applications, purchasers will find that energy-efficient products have the lowest life cycle cost.

Agencies may claim an exception to federal purchasing requirements through a written finding that no ENERGY STAR-qualified or FEMP-designated product is available to meet functional requirements, or that no such product is life cycle cost-effective for the specific application. Get additional information on federal product purchasing requirements.

Federal Supply Sources and Product Codes

The federal supply sources for energy-efficient products are the General Services Administration (GSA) and the Defense Logistics Agency (DLA). 

The U.S. Department of Agriculture (USDA) and U.S. Environmental Protection Agency (EPA) provide programs that help federal agencies buy products with positive environmental attributes.

Identification codes for product categories covered by sustainable acquisition requirements are provided by DLA and the United Nations Standard Products and Services Code (UNSPSC).

GSA Resources

Under the Multiple Award Schedule program, GSA issues long-term governmentwide contracts that provide access to commercial products, services, and solutions at pre-negotiated pricing.


DLA Resources

DLA offers products through the Defense Supply Center Philadelphia and online through FedMall (formerly DOD EMALL).


Products sold through DLA are codified with a 13-digit National Stock Number (NSN) and, in some cases, a two-letter Environmental Attribute Code (ENAC). The ENAC identifies items that have positive environmental characteristics and meet standards set by an approved third party, such as FEMP and ENERGY STAR.

USDA BioPreferred Program

USDA's BioPreferred Program was created to increase the purchase and use of biobased products. Federal law, the FAR, and Presidential Executive Orders direct that all federal agencies and their contractors purchase biobased products in categories identified by USDA. 


EPA and Other Industry Resources

EPA offers several resources for choosing which products to buy. The Environmentally Preferable Purchasing Program helps federal government purchasers utilize private sector standards and ecolabels to identify and procure environmentally preferable products and services.


UNSPSC Resources

UNSPSC is a worldwide classification system for e-commerce. It contains more than 50,000 commodities, including many used in the federal sector, each with a unique eight-digit, four-level identification code. Manufacturers and vendors are beginning to adopt the UNSPSC classification convention and electronic procurement systems are beginning to include UNSPSC tracking in their software packages. UNSPSCs can help the federal acquisition community identify product categories covered by sustainable acquisition requirements, track purchases of products within those categories, and report on progress toward meeting sustainable acquisition goals. 


Water-Cooled Chiller Schedules and Product Codes

GSA offers chillers through Multiple Awards Schedules Industrial Products 333415REM and Industrial Products 335220D.

The DLA ENAC for water-cooled chillers is "JU."

The UNSPSC for water-cooled chillers is 40101711.

Buyer Tips: Make Informed Product Purchases

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 (see FEMP's Covered Product Category: Air-Cooled Electric Chillers). 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. A chiller optimized for high full-load efficiency is appropriate for full-load operating conditions; for a chiller that will be operated at part load, a chiller optimized for high IPLV efficiency is appropriate.

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.

Many new energy consuming water-cooled chillers come equipped with Internet of Things (IoT) sensing components, and network connectivity. Making a new purchase or replacement represents a prime opportunity to evaluate the vulnerabilities of your network. All IoT-enabled devices introduce novel 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 existing FEMP guidance and case studies.


Lawrence Berkeley National Laboratory provided supporting analysis for this acquisition guidance.