A survey by Dell in 2006 found that more than half the power consumed at datacentra is not used for ICT services. Only Two fifths went to ICT resources, one third for cooling and the rest disappeared in such things as lighting and emergency power. For benchmark energy efficiency of a data center, the Power Usage Effectiveness (PUE)-formula is quite common.
According to figures from Dell, the average PUE in the pre-virtualization year 2006 was 2.5. Which means that for every Watt spent on ICT there is a loss of 1.5 watts. In the meantime most companies start virtualization to save power, space and cooling. But recent charts shows that there is still an upward trend in the total power consumption of computer centers. Not illogical as our dependence on ICT is also increased.
