While there are a number of datacenter efficiency metrics that are becoming widely accepted, they all, for the most part suffer from the same flaw. While they are able to quantify the energy usage of the facility there are rarely able to accurately reflect the amount of work being done for the energy consumed. This is, in part, due to the difficulty in defining a work metric; exactly how you define what the accomplishment of any given workload is, and how would you measure it in comparison to other workloads.
Verizon decided to take the big picture approach to defining one current efficiency metric; workload vs carbon emissions. Their carbon intensity metric doesn't simply evaluate the amount of carbon emissions from their datacenters and compare it to the datacenter workload. It goes the distance and measures the carbon usage of the entire company; everything from the electricity used in their datacenters to the fuel used in their vehicles.
Verizon then takes that number and compares it to their workload. In this case, it's a fairly easily definable number; they use the amount of data that they move across their network. Since at the bottom line, that's their business, their metric now lets them compare, on a year to year basis, how efficient they have been in moving to greener technologies, not just in their datacenters, where the data is being moved, but across the entire company. In 2010, Verizon moved a little under 80 million terabytes across their networks, an increase of 16% over 2009. For 2011 Verizon is using the metric to see if they meet their target goal of a 15% improvement in energy efficiency.
This improvement goes beyond just the datacenter; for example by increasing their fleet of hybrid vehicles and looking for ways to improve the energy efficiencies of buildings they improve their overall carbon usage metric and are able to deliver data more efficiently as a company, not just as a datacenter user.