Data center operators that have created their own custom metrics for benchmarking productivity of their facilities are the more mature among their peers.

Former Green Grid executive director Mark Monroe, whose current role is CTO and VP at the engineering firm DLB Associates, said the more generic a metric gets, the less valuable it becomes for each specific operator.

Monroe sat on a panel of industry experts that discussed ways to measure data center efficiency at Tuesday's DatacenterDynamics Converged conference in New York.

While Power Usage Effectiveness (PUE) is the most well-known metric for data center efficiency, it is not necessarily the best one to use for every operator.

PUE, which was created by HP and donated to the Green Grid, is a good metric when used for its intended purpose, Monroe said. “For what it was designed, I think it's very useful.”

The metric was always meant for internal use by data center operators who wanted to benchmark efficiency of their facilities.

It is also a simple way to communicate data center efficiency to non-technical business leaders. “It's simple to collect; it's simple to understand,” Monroe said.

Many companies, however, have been using it to promote themselves externally, publicizing their PUE numbers to show how efficient they are. This use is incorrect since there are ways to “tweak” the measurement process to lower the number.

Sarah Rambacher, project manager at New York State Energy Research and Development Authority (NYSERDA), said the state-run organization does not use PUE for its energy efficiency incentive program for data centers because the metric is meant for internal use.

When deciding whether to reward a data center operator for increasing efficiency, NYSERDA looks for defensible metrics, which are different for every customer, Rambacher said.

Time Warner Cable uses PUE to assess its data center efficiency, but has also come up with efficiency metrics of its own that work for its specific business. One of them measures the amount of power it takes the company's “hub” data centers to serve one customer.

Ryan Capone, director of critical infrastructure for New York City and other northeastern markets at TWC, said the company used the watts-per-customer metric to make decisions around capacity planning and hardware refresh.

The data center team at Syracuse University has also come up with its own ways to measure efficiency. Christopher Sidore, associate vice chancellor for academic operations at the university, said this was a good example of a unique facility where a generic metric was not good enough.

The data center has it own on-site gas-fueled power generation plant and houses infrastructure for research as well as for general IT purposes, running at very different utilization rates.