They found one crucial area to improve: their 65 computer-room air handlers. Parrino and his team found that some of their power distribution units had perforated tops. "We were losing all sorts of air through the tops of the cabinets," he says, which meant that some of the cool air circulated by the air handlers was being wasted by cooling the PDUs. They restricted the air flow through the cabinets, tested to make sure they wouldn't overheat, then turned 24 air handlers off.

The move has saved UPS 1.6 million kilowatt-hours and about $124,160 per year. And that's not all—they also benchmarked their mechanical cooling system and were able to reduce its energy use, saving an additional $100,000 annually. The mechanical plant of these UPS data centers consumes about half what a typical data center mechanical plant consumes, according to their benchmarking study, Parrino says.

Despite the potential for savings, however, most IT departments have not rushed to benchmark data center energy efficiency, primarily because there's no incentive to measure it, says Forrester analyst Doug Washburn. He notes that only 11 percent of IT organizations are responsible for paying their energy-related operating costs (the power bill typically goes to the facilities group). But that's changing: More CIOs are being asked to reduce energy consumption, Washburn has found, and, as a result, new metrics—though they come with caveats—appear to help pinpoint which areas of your data center can be optimized.

Two Ways to Benchmark

One such method of measuring energy efficiency, developed recently by the Uptime Institute, a data center research organization, is Corporate Average Datacenter Efficiency (CADE). This calculation multiplies the efficiency of one's technology by the efficiency of the physical facility. Uptime calculates IT efficiency by multiplying a data center's IT asset utilization rate by the energy efficiency of the servers. It determines the facility efficiency by calculating the amount of space used and multiplying that by the energy efficiency of the building. The higher the CADE number, the more efficient your data center. This method tends to be best-suited for larger businesses since those usually have the automated monitoring tools to measure server utilization, according to Uptime Institute's Executive Director Kenneth Brill.