For many years now, there has been a list of the Top 500 supercomputers in the world as measured by computational speed. But is speed the only metric that a supercomputer should be measured by?
Almost certainly not. In recent years, the discussion has changed as awareness of data center energy consumption has become an important topic. These top supercomputers are, in many cases, egregious offenders of energy consumption.
Thus, the Green 500 list was born: a list of supercomputers (taken from the Top 500) arranged by energy efficiency. This makes for interesting reading, and helps raise the awareness that computational power is not the only reason to buy a computer.
UNIX Administratosphere 