Green IT is not only good for the environment, it also saves enterprises money by reducing operational costs of IT. In two-part series of articles in Symantec’s CIO Digest Magazine,Editor-in-Chief Patrick Spencer reviews the economic benefits of taking a greener approach to IT in terms of reduced capital spending through server and storage consolidation and reduced operational costs largely due to more efficient consumption of electricity. In the second article, Spencer reviews the two most widely used green IT efficiency metrics—Power Usage Efficiency (PUE) and Carbon Usage Efficiency (CUE) and how to calculate them. The articles appear in the October 2011 and January 2012 issues of CIO Digest.