The Federal Energy Management Program (FEMP) provides acquisition guidance for water-cooled electric chillers, a product category covered by FEMP efficiency requirements. Federal laws and requirements mandate that agencies purchase ENERGY STAR-qualified or FEMP-designated products in all product categories covered by these programs and in any acquisition actions that are not specifically exempted by law.
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.
This acquisition guidance was updated in August 2016.
Find Product Efficiency Requirements
Federal purchases must meet or exceed the minimum efficiency requirements in Table 1.
|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||Full Load Efficiency||Integrated Part-Load Value|
|Positive Displacement||< 75||0.736||0.600||0.780||0.500|
|75 to 149||0.720||0.560||0.750||0.490|
|150 to 299||0.651||0.540||0.680||0.440|
|300 to 599||0.610||0.520||0.625||0.410|
|150 to 299||0.610||0.550||0.635||0.400|
|300 to 399||0.560||0.520||0.595||0.390|
|400 to 599||0.560||0.500||0.585||0.380|
Make a Cost-Effective Purchase: Save $19,300 or More by Buying a FEMP-Designated Product
FEMP has calculated that a 225-ton water-cooled positive displacement chiller meeting the required 0.651 kW/ton efficiency level saves money if priced no more than $19,300 above the less efficient model. The best available model saves the average user more: $36,600 above the less efficient model. Table 2 compares three types of product purchases and calculates the lifetime cost savings of purchasing efficient models. Federal purchasers can assume products that meet FEMP-designated efficiency requirements are life cycle cost-effective. FEMP provides cost calculators that enable comparison between the cost-effectiveness of chillers of different efficiency levels.
|Table 2. Lifetime Savings for Efficient 50-ton Water-Cooled Positive Displacement Chillers in Full-Load Applications|
|Performance||Best Available||Required Model||Less Efficient|
|Full Load Efficiency (kW/ton)||0.625||0.651||0.680|
|Annual Energy Use (kWh)||281,250||292,950||306,000|
|Annual Energy Cost ($/yr)||$25,313||$26,366||$27,540|
|Lifetime Energy Cost (23 years)||$416,229||$433,544||$452,857|
|Lifetime Energy Cost Savings||$36,628||$19,313||-----|
Full Load Efficiency: Defined as the ratio of energy consumption in kilowatt-hours to the cooling capacity in refrigeration tons at the rated condition. The lower the kW/ton the more efficient the chiller.
Annual Energy Use: Assumes a chiller operating 2,000 hours per year for 23 years.
Annual Energy Cost: Calculated based on an assumed electricity price of $0.09/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 Energy Price Indices and Discount Factors for Life-Cycle Cost Analysis – 2015: Annual Supplement to NIST Handbook 135 and NBS Special Publication 709 (NISTIR 85-3273-30).
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 the highest efficiency model identified in publicly provided manufacturer data as of August 2016. 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 the previous FEMP acquisition guidance for this product type.