Ken Brill has a commentary written in Forbes.com promoting the use of the CADE Metric.
I define a green data center as delivering the most productivity for the least amount of energy consumed. Will Forrest of McKinsey & Co. and I have defined a measure we call the Corporate Average Datacenter Efficiency (CADE) as being a useful--and, currently, the only--metric for measuring the combination of data center productivity and energy consumption.
CADE, while not perfect, divides overall data center efficiency into four individual measures, each of which can be separately measured and benchmarked. These elements include measures of IT asset efficiency and utilization as well as the asset efficiency and utilization of the physical facility that houses these assets. (You can read the report here.)
Nothing really new in this article.
There are some experts who have opinions on CADE, but no one has stepped up with an alternative view.