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Who Offers ENERGY STAR Servers?

Twelve manufacturers offer ENERGY STAR® qualified servers, down from seventeen in 2013. Symantec and Unify are the latest to offer products. Energy consumption is only one criteria for choosing the greenest server, but there are no comprehensive ratings of green servers.

Enterprise Servers
Small Scale Servers
The information is distributed across two disconnected sections on the ENERGY STAR site: Enterprise Servers and Small Scale Servers. The site reports 150 models available in the United States and 131 in Canada.

Users looking to purchase green PCs and monitors should reference EPEAT. EPEAT qualified products comply with a wide range of green criteria in addition to ENERGY STAR. You can access information about EPEAT Gold products through the top three "Greenest E-Gear" links on the right.

Some have evaluated ENERGY STAR - Computer Servers 1.0 a "good first step" but conclude the requirements "have enough shortcomings that they are unsuitable to be primary criteria for the purchase of new hardware equipment." Version 2.0 is in progress, but without a target completion date.

EPA's case study "Energy Savings From ENERGY STAR-Qualified Servers" concludes:

Our findings imply that..the energy savings from a single ENERGY STAR-qualified server could range from $60 (at 50% utilization) to $120 (at idle) annually, or $240-$480 over the useful life of a server (4 years).
...ENERGY STAR-qualified servers substantially reduce cooling loads in data centers. A general rule of thumb suggests that one watt saved by a server has the added benefit of saving one to two watts of cooling power. This yields a total savings of between $480 and $1,440 over the useful lifetime of a server.
...these power savings come with a substantial increase in performance—at 50% utilization, for example, the newer, more energy-efficient server handles over three times the workload, thereby reducing the number of systems needed to support the same load.
Our data suggests that a single ENERGY STAR-qualified server saves enough electricity to avert nearly 1/2 to 1 ton of carbon dioxide emissions, based on the assumptions stated above. Accounting for cooling savings makes it a total of 1 to 3 tons of carbon dioxide abated.

It is important to remember that power consumption is not the only criteria for choosing the greenest server. Apple offers a good example in its environmental report for the Mac mini, the platform for OS X Server. It shows that only 30% of life-cycle CO2e, which is tied to power consumption, comes from customer use. The Apple report also examines material use, including RoHS substances, and packaging. Purchasers need to consider all these factors .