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Energy Audit Shows How Data Center Efficiency Can Save Millions

Although most IT press is focused on the ever-shrinking PUEs of leading-edge data centers (present company included, of course), the results of Digital Realty Trust's data center energy audits show just how big the results are from even "run of the mill" energy efficiency projects.

DRT, which builds and manages high-tech real estate, earlier this month published the results of an energy audit of two of its data centers, one in San Francisco and one in Santa Clara, and found that its customers were achieving an average power usage effectiveness ratio of 1.6.

While 1.6 is a far cry from the PUEs that we're seeing from model data centers from eBay (1.4), Google (1.2), Hewlett-Packard (1.18), Microsoft (1.12), and MegaWatt Consulting (1.05), DRT shows that even getting to 1.6 PUE from the industry average of 2 or 2.5 can have significant benefits.

How significant? DRT says they're saving between $6 and $10 million per year in energy costs by being more energy efficient than the average.

The table below lays out the company's energy usage and savings:

Overall IT Capacity of Datacenters 20,850 kW
Total Utility Draw 18,060 kW
Current Utilization by Customers 11,236 kW
Current Utilization Rate 53 percent
PUE Rating 1.6
Estimated Power Savings 10,000 kW annually
Estimated Cost Savings $6-10 million annually


In addition to its customers' green IT best practices, DRT is putting a number of technologies to work in bringing down its PUE, including:

  • Variable frequency drives on fans, pumps and chillers
  • Outside air economization with differential enthalpy control
  • Higher operating temperatures in the datacenters
  • LEED Platinum buildings
  • PowerVu monitoring software
  • Hot and cold aisle containment

"This is industry-leading energy efficiency for such a large IT load over so many properties, especially when you take into account that customers are only at 53 percent utilization," Jim Smith, CTO of Digital Realty Trust, said in a statement. "The industry average for datacenter PUE is in the 2.5 range. A PUE of 1.6 is outstanding, and is a tribute to the effectiveness of our energy efficiency and sustainability program. Compared to industry averages, these Turn-Key Datacenters are saving an estimated 10,000 kW a year in electricity usage, which translates into millions of dollars of estimated cost savings for our customers annually."

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