By Steve Ryan, Robert Huang and Allison Bard
Data centers use an astounding 2% of the nation’s electricity. And for a number of years, the EPA Energy Star program has focused on providing companies with tools to gain a better understanding of the efficiency of their data center. For example, EPA’s building energy efficiency tool, portfolio manager, allows a company to compare their data center’s efficiency with hundreds of other data centers from across the country. Data centers that fall within the top 25% earn Energy Star certification. (Energy Star is a voluntary program that helps businesses and individuals save money and protect the climate through superior energy efficiency.)
Target, one of the largest retailers in the United States, recently shared information with the EPA about a series of cost-effective energy-efficiency upgrades on two 45,000-sq.-ft. centers in Minnesota. As a result of the efficiency upgrades, Target was the first company to have two data centers earn the Energy Star building certification and was named an EPA Energy Star Low Carbon IT Champion in 2012.
Target took the following actions:
• Installed variable frequency drives (VFDs) on air conditioning units: VFDs allow fans to run at lower speeds by controlling the frequency of the electrical power supplied to the fan motor. Fan power consumption is proportional to the cube of fan speed, so a decrease in fan speed can lead to extraordinary reductions in fan energy use.
• Reduced temperatures on generator heaters: The temperature of generator heaters could be lowered from 140 to 110 degrees Fahrenheit because each was located within conditioned space.
• Installed timers and efficient lighting: Timers were installed to turn lights on at 6:00 a.m. and off at 4:30 p.m.
• Turned off unloaded transformers: Two unloaded power distribution units (PDUs) were taken offline at the Elk River data facility, where the computing load was not yet completely built out.
Target’s data center retrofits led to the savings of more than 5.8 million kWh annually (more than $500,000 in savings) and, on average, paid back in 1.4 years, including utility rebates. The annual carbon emission reduction achieved through these efforts is the equivalent of taking 800 cars off the road.
Steve Ryan, EPA Energy Star, Robert Huang and Allison Bard, Cadmus Group