When it comes to cleaning up their act, many CIOs are recognizing data centres as among the lowest hanging fruit. IDC estimates companies spent $US26.1 billion to power and cool servers worldwide in 2005, with a monstrous $14 billion of that being spent in the US alone. In fact, data centres account for between 1.5 and 3 percent of all electricity consumed in the US. Should current trends persist, the research organization projects, that bill will soar to $US50 billion by the end of the decade.

The deployment of high-density servers is making the situation far, far worse than ever before.

If CIOs adopt a virtualization strategy, there will be fewer physical servers, which means less space in the data centre, and less electricity and cooling

"The power needed for a rack of high-density server blades can be between 10 and 15 times higher than the power needed for a traditional server environment," says Gartner research vice president Rakesh Kumar. "Most legacy data centres built 15 to 20 years ago cannot meet this demand. At the same time, a similar amount of additional power will be needed to remove the huge quantity of heat generated by these new machines. If the machines are not cooled sufficiently, they will shut down, with potentially damaging consequences for business service levels and IT governance."

Factor in the rising cost of electricity and Gartner says all this gives businesses a double incentive to cut carbon emissions.

Leading UK fixed-line telecommunications provider BT currently consumes an astonishingly high 0.7 percent of the UK's total annual electricity output, according to a case study by IDC. BT knows that rationalizing its large installed base of systems and infrastructure that includes most of the major switch, router, server and storage vendors' equipment and multiple applications that address customer needs and different parts of the business is essential to reducing its carbon emissions, IDC says.

BT is succeeding. The company slashed carbon emissions by 60 percent between 1996 and 2006 and aims to extend that figure to 80 percent by 2016.