Purchasing Energy-Efficient Uninterruptible Power Supplies

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Battery lifetime is dependent on ambient temperature. Consider locating the unit in an air-conditioned area. Each 15° Fahrenheit temperature rise decreases lifetime by 50%.

The Federal Energy Management Program (FEMP) provides acquisition guidance for uninterruptible power supplies (UPS), a product category covered by ENERGY STAR efficiency requirements. 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.

FEMP's acquisition guidance and associated ENERGY STAR efficiency requirements for UPS are technology neutral, meaning that one technology is not favored over another. However, ENERGY STAR's product specification requirements apply to UPS products intended for use in consumer, commercial, telecommunications (DC-output), and data center applications. UPS products that are internal to computers or other electronic devices; designed for industrial applications; part of an electric transmission or distribution system; used in mobile (e.g., marine, airborne) applications; or part of a cable television network are excluded.

This acquisition guidance was updated in January 2017.

Find Product Efficiency Requirements

The U.S. Environmental Protection Agency (EPA) provides UPS efficiency levels and product specification information on its ENERGY STAR website. Manufacturers meeting these requirements are allowed to display the ENERGY STAR label on complying models. Get a list of ENERGY STAR-certified UPS.

Make a Cost-Effective Purchase: Save Up to $44 by Buying Energy Star

FEMP has calculated that the required ENERGY STAR-certified 900-watt voltage independent (VI) UPS saves money if priced no more than $35 above the less efficient model. The best available product saves $44. Table 1 compares three types of UPS purchases and calculates the lifetime cost savings of purchasing efficient models. Federal purchasers can assume products that meet ENERGY STAR efficiency requirements are life cycle cost-effective.

Table 1. Lifetime Savings for Efficient Voltage Independent UPS
PerformanceBest AvailableENERGY STARLess Efficient
Average Efficiency (kWh)98.8%98.4%97.3%
Annual Energy Use (kWh)7493163
Annual Energy Cost$6.67$8.38$14.67
Lifetime Energy Cost$36.75$46.16$80.81
Lifetime Cost Savings$44.06$34.66=====
View the Performance and Model Assumptions for Table 1
Performance Column

Annual Energy Use: Based on ENERGY STAR values and typical reported values for 900-W voltage-independent UPS, listed in kilowatt-hours. Typical reported values are from Xergy Consulting's June 2016 report, Determining a Real-World Adjustment Factor for Computer Energy Use: Laboratory Testing the Impact of Real-World Idle, Active Mode and Peripherals (Docket #14-AAER-2).

Annual Energy Cost: Calculated based on an assumed electricity price of $0.09/kWh, which is the average electricity price at federal facilities throughout the United States. Learn more about Federal Government Energy/Water Use and Emissions.

Lifetime Energy Cost: Calculated as the sum of the discounted value of the annual energy cost over the assumed product life of 6 years. Future electricity price trends and a 3% discount rate are from Energy Price Indices and Discount Factors for Life-Cycle Cost Analysis – 2016: Annual Supplement to NIST Handbook 135 and NBS Special Publication 709 (NISTIR 85-3273-31).

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

Best Available Model Column

Calculated based on the December 2016 ENERGY STAR List of Qualified Products. More efficient models may be introduced to the market after FEMP's acquisition guidance is posted.

Energy Star Model Column

Calculated based on December 2016 ENERGY STAR efficiency levels. Federal agencies must purchase products that meet or exceed ENERGY STAR efficiency levels.

Less Efficient Model Column

Calculated based on typical products used in non-federal applications.

Determine When ENERGY STAR 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. ENERGY STAR considers up-front costs and lifetime energy savings when setting required efficiency levels. Federal purchasers can assume ENERGY STAR-qualified products and products that meet 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 federal efficiency requirements (e.g., the best available model).

Claim an Exception to Federal Purchasing Requirements

Products meeting ENERGY STAR or 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 FEMP-designated or ENERGY STAR-qualified product is available to meet functional requirements, or that no such product is life cycle cost-effective for the specific application. Learn more about federal product purchasing requirements.

Incorporate Federal Acquisition Regulation Language in Contracts

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. 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.

Find Federal Supply Sources

The federal supply sources for energy-efficient products are the General Services Administration (GSA) and the Defense Logistics Agency (DLA). GSA sells products through its Multiple Awards Schedules program and online shopping network, GSA Advantage!. DLA offers products through the Defense Supply Center Philadelphia and online through 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.

The United Nations Standard Products and Services Code (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. FEMP has developed a table of ENERGY STAR and FEMP-designated covered product categories and related UNSPSC numbers.

Uninterruptible Power Supplies Schedules and Product Codes

GSA offers UPS through Schedule 56 (Buildings and Building Materials/Industrial Services and Supplies).

DLA does not currently offer an ENAC for UPS models.

The UNSPSC for UPS is 39121011.

Buyer Tips: Make Informed Product Purchases

When selecting a UPS for your downstream equipment, consider equipment type, size, and number; the level of power conditioning required; redundancy; and the length of uptime required in the event of an outage. In applications where future growth is expected, such as data centers, consider using modular UPS systems that can expand in proportion with the load.

Voltage and frequency dependent (VFD), voltage independent (VI), and voltage frequency independent (VFI) UPS systems offer different levels of power conditioning. VFD models provide the most basic level of protection, while VFI models offer the highest level of protection for downstream equipment; the protection function of VI models fall between that of VFD and VFI. Higher levels of power conditioning generally result in lower UPS system efficiency, so choose the lowest level of protection needed for your application.

For battery-based UPS systems, use a design approach that keeps the load factor as high as possible, and account for any peak-load and partial-load operating conditions. The efficiency of UPS systems varies with loading; typically the more highly loaded they are, the more efficient. Lightly loaded systems could be losing 15% or more of the energy supplied to the equipment downstream. The loss is from the power conversion within the UPS, which creates heat that must then be managed. For systems that are constantly operated below design conditions, consider a modular UPS system to accommodate partial-load conditions and future growth.

Accurate equipment load estimates can prevent gross over-sizing and the resultant under-loading of UPS systems. Selecting efficient UPS models, coupled with right-sizing the system, can result in direct 24-hour-a-day energy savings by reducing both UPS and cooling power consumption. When purchasing new UPS systems, look for models that are efficient through most of the design range and that allow power data collection to track power usage.

UPS systems are often used in data centers. Agencies should consult the Center of Expertise for Energy Efficiency in Data Centers website for information on energy-efficient design strategies and opportunities. DOE has partnered with key public and private stakeholders to provide technical information, tools, best practices, and analysis that assist government agencies with reducing energy use in data centers. Purchasing efficient products for use in data centers can be an important component to meeting data center energy reduction goals.

User Tips: Use Products More Efficiently

When using multi-normal-mode UPS systems, consider switching to lower energy-consuming modes during operations for which the highest level of protection is not required. Check the UPS periodically to ensure battery and capacitor parts are maintained per manufacturers' instructions.

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