There is lots of press around that the IBM Roadrunner supercomputer at Los Alamos National Laboratory is being turned off.
The one I found most useful is the Arstechnica article where the energy efficiency is mentioned.
Petaflop machines aren't automatically obsolete—a petaflop is still speedy enough to crack the top 25 fastest supercomputers. Roadrunner is thus still capable of performing scientific work at mind-boggling speeds, but has been surpassed by competitors in terms of energy efficiency. For example, in the November 2012 ratings Roadrunner required 2,345 kilowatts to hit 1.042 petaflops and a world ranking of #22. The supercomputer at #21 required only 1,177 kilowatts, and #23 (clocked at 1.035 petaflops) required just 493 kilowatts.
Given the high power consumption it would seem most likely this is the actual power draw, not the additional power for the cooling system. A pre-2009 super computer would most likely have over 50% for the cooling system, so this could easily be 3.5MW of power.
Supercomputers are regularly rated on its energy use. And, the author highlights there is a need for a better performance per watt.
"Future supercomputers will need to improve on Roadrunner’s energy efficiency to make the power bill affordable," Los Alamos wrote. "Future supercomputers will also need new solutions for handling and storing the vast amounts of data involved in such massive calculations."