Jerry Rutkowski, 1E’s Director of Strategic Accounts, Federal has a really nice article posted about server efficiency on the Environmental Leader web site today. You may think that just because servers are now the size of “pizza boxes” that they are entirely efficient and power consciousness. In truth, we have come a long way over the last 10 years, but there’s still further to go. The hardware may be efficient, but running them efficiently is a different story altogether.
As Jerry states:

You may buy the most energy efficient servers available today but in actuality you may not run them efficiently. Research Server energy and efficiency report, Alliance to Save Energy shows that servers use about 60 percent of their maximum power while doing nothing at all and typically only run at around 15 percent utilization.

Take a read through Jerry’s article to see if there are some areas of efficiency in the datacenter that are still not realized in your organization.
Full article:
https://www.environmentalleader.com/2011/11/07/are-your-servers-running-efficiently/