UPS Energy Star Program's Preliminary Results

Julius Neudorfer
So you think that the uninterruptible power supply (UPS) that you are about to purchase is the most energy efficient? While it is still too early to look for the official answer to that question, later this year the Environmental Protection Agency (EPA) may have the answer for you.

According to a stakeholder's memo issued Feb. 2 by Robert Meyers of the EPA to the UPS Energy Star program participants, Phase-1 results of the uninterruptible power supplies efficiency tests that were completed as of Jan. 14, 2011 are now publicly available.

The program began in February 2010, with a call to the UPS industry and end users. This information was originally scheduled to be released in October 2010 but was delayed. The Phase-2 testing program will continue using the new Draft ENERGY STAR Test Method until March 18. The results and finalized program specifications are scheduled for July 2011.

Here's what the UPS stakeholders' memo says about testing:

Summary of Phase 1 Data

Five manufacturers shared the results of 236 previously conducted tests for inclusion in the dataset. The UPSs tested included both consumer and datacenter units, across a wider range of rated output power.

Phase 1: Sharing of existing test data (through January 14, 2011): By first analyzing existing test data obtained according to draft versions of IEC 62040-3, EPA hopes to identify any gaps in testing as well as potential opportunities for energy savings that can be confirmed through new testing. Also, this time will allow manufacturers to validate the test method and data entry sheets and set up their labs for testing. 
Phase 2: New testing according to Draft ENERGY STAR Test Method (through March 18, 2011): After analyzing the existing test data shared during the first phase, EPA will work with manufacturers to identify the most pressing data needs and ensure that sufficient data are generated. By focusing the new testing, EPA hopes to assemble a robust dataset more quickly, which will support timely development of the final specification.

The EPA Energy Star efficiency testing is based in part on the IEC 62040-3 Loading Points for UPS. This test requires that the UPS be loaded at four load levels: 100 percent, 75 percent, 50 percent and 25 percent of their rated load. This IEC UPS test standard is not new, but is not mandated, nor is it always used by UPS manufacturers, and many times the results are not readily available to end user customers.

At this point in the EPA program, only five UPS vendors volunteered test information. Not all vendors submitted results at the four required load steps. Some just provided efficiency information at 100 percent load or at the point where their unit was at its highest efficiency. The information was tabulated by the EPA, but the comparative results that were compiled and just made public were anonymous so that no brand-related information was revealed. One chart indicated that some UPS units were able to operate at 90 percent efficiency even at 25 percent of rated load, while others were at 80 percent or less.

In a typical data center scenario, most UPSes are not operating anywhere near full load, quite the opposite in fact, because of the need for redundancy. Unfortunately UPS redundancy configurations and load efficiency curves point in opposite directions. The majority of data center UPS units are operating at less than 50 percent load and a significant number at 25 percent or even lower. 

Ultimately those manufacturers that choose to submit their UPS for the Energy Star label will have to publish all the required test results in order to be certified, like all other Energy Star-rated products. From the IT and data center perspective, the UPS will soon join Energy Star servers in the rating game. EPA is also currently progressing on defining the requirements for data storage systems and networking equipment, as the next rating target for Energy Star certification.

The Bottom Line

The good news is that the Energy Star Program will help level the playing field for efficiency bragging rights by the various UPS manufacturers and provide a valid basis of efficiency comparison for the end user. Currently, most manufacturers only list their highest efficiency points in their marketing materials (typically somewhere at or near 100 percent load). 

So while it seems that many manufacturers' marketing claims of over 90 percent efficiency look attractive at first when shopping for a UPS, ask for the complete performance curve covering the lower load areas where you may be operating your equipment. And as usual, remember that your actual mileage may vary.

Add Comment      Leave a comment on this blog post
Feb 9, 2011 4:02 PM Prabhakar Nerella Prabhakar Nerella  says:
Very good efforts in bringing the facts about UPS efficiency to protect consumers. This should help consumers in saving some $ from power bill as well saving our mother earth. hope this should help best performer to get benefited. -prabhakar. Reply

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