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Covered Product Category: Uninterruptible Power Supplies

The Federal Energy Management Program (FEMP) provides acquisition guidance and Federal efficiency requirements for uninterruptible power supplies (UPS), which are covered by the ENERGY STAR program. Federal laws and executive orders mandate that agencies meet these efficiency requirements in all procurement and acquisition actions that are not specifically exempted by law.

This acquisition guidance and associated ENERGY STAR product specifications apply to consumer, commercial, data center, and telecommunications (DC-output) UPS products.

Meeting Energy Efficiency Requirements for Uninterruptible Power Supplies

ENERGY STAR Qualified ProductsBuy products that have the ENERGY STAR label. A list of ENERGY STAR–qualified UPS products is available from ENERGY STAR. For the most up-to-date efficiency levels required for this product category, visit the ENERGY STAR UPS website. For more information, or for a point of contact, visit the Resources for Energy-Efficient Products page.

Reducing Energy Costs: Save Up To $189 When You Buy ENERGY STAR–Qualified Products

Voltage and Frequency Dependent UPS

FEMP has calculated1 that a 300-watt voltage and frequency dependent (VFD) UPS meeting the minimum ENERGY STAR efficiency requirement saves money if priced no more than $25 above the less efficient alternative. The best available product saves the average user even more: $28. The complete cost effectiveness for a 300-watt VFD UPS operated at 25% load is provided in Table 1 below.

Table 1. Lifetime Savings for Efficient VFD UPS
Performance Best Availablea ENERGY STAR Required Less Efficient
Average Efficiency 97.5% 96.7% 92.0%
Annual Energy Use 680 kWh/year 690 kWh/year 750 kWh/year
Annual Energy Cost $61 $62 $68
Lifetime Energy Cost $280 $283 $308
Lifetime Energy Cost Savings $28 $25 ======

a More-efficient products may have been introduced to the market since this table was published.

 

Voltage Independent UPS

FEMP has calculated that a 2,700-watt voltage independent (VI) UPS meeting the minimum ENERGY STAR efficiency requirement will save money if priced no more than $134 above the less efficient alternative. The best available product saves even more: $189. The complete cost effectiveness for a 2,700-watt VI UPS operated at 25% load is provided in Table 2 below.

Table 2. Lifetime Savings for Efficient VI UPS
Performance Best Availablea ENERGY STAR Required Less Efficient
Average Efficiency 98.2% 96.7% 93.5%
Annual Energy Use 6,040 kWh/year 6,180 kWh/year 6,500 kWh/year
Annual Energy Cost $544 $556 $585
Lifetime Energy Cost $2,481 $2,536 $2,670
Lifetime Energy Cost Savings $189 $134 ======

a More-efficient products may have been introduced to the market since this table was published.

 

ENERGY STAR Is Cost Effective

An efficient product is cost effective when the discounted savings (from avoided energy costs over the life of the product) exceed the additional upfront cost (if any) compared to a less efficient option. ENERGY STAR considers upfront costs and lifetime energy savings when setting required efficiency levels. Federal purchasers can assume that ENERGY STAR-qualified products are life cycle cost effective.

Exceptions

For most applications, purchasers will find that energy-efficient products have the lowest life cycle cost. Agencies may claim an exception to these purchasing requirements through a written finding that no ENERGY STAR-qualified product is available to meet functional requirements, or that no ENERGY STAR-qualified product is life cycle cost effective for the specific application. Additional information on Federal requirements is available.

Complying with Contracting Requirements

These requirements apply to all forms of procurement, including project specifications; renovation, repair, maintenance, and energy service contracts; lease agreements; acquisitions made using purchase cards; and solicitations for offers. Energy efficiency requirements should be included in both the evaluation criteria of solicitations and the evaluations of solicitation responses.

Federal Acquisition Regulation (FAR) Part 23.206 requires Federal agencies to insert the clause at FAR section 52.223-15 into solicitations and contracts that deliver, acquire, furnish, or specify energy-consuming products. FEMP recommends that agencies incorporate efficiency requirements into both the technical specification and evaluation sections of solicitations.

Note that UPS systems are often acquired through IT service providers. Make sure that such IT service contracts contain appropriate pass-through provisions to require the purchase of ENERGY STAR-qualified products.

Buyer Tips: Choosing Efficient Products

When selecting a UPS for your downstream equipment, you should consider equipment type, size, and number; the level of power conditioning required; future growth/expansion plans; redundancy; and the length of uptime required in the event of an outage.

VFD, 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 you should 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.

User Tips: Using 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.

Finding More Information

For more information, see  Resources for Energy-Efficient Products.

Updated January 2013

1Based on the following assumptions for Tables 1 and 2: Annual energy use is based on the AC-output Loading Assumptions contained in the ENERGY STAR Eligibility Criteria (Rev. July 2012) for a unit operating continuously (8,760 hours per year). The assumed electricity price is $0.09 per kWh, the Federal average electricity price. Lifetime energy cost is the sum of the discounted value of annual energy cost over the assumed 5-year operating life of the device. Future electricity prices and a 3% discount rate are from Energy Price Indices and Discount Factors for Life-Cycle Cost Analysis - 2012: Annual Supplement to NIST Handbook 135 and NBS Special Publication 709 . (NISTIR 85-3273-27)