For all the talk of paperless offices and workers ditching company cars to work from home via the web, the IT revolution’s green credentials are actually rather poor.

IT accounts for about 2 per cent of CO2 emissions, according to Gartner, the analysts - the same proportion as the aviation industry. PCs account for 40 per cent of that.

"Always on computing" has made for a snappy IT industry sales phrase, but does little for the planet or companies' bottom lines. Fujitsu Siemens, the IT group, estimates that the UK's largest 200 companies could collectively save £123 million a year if they turned off PCs at night.

Away from the office, such is the thirst for electricity from the data centres that store digital information and carry web traffic, London has effectively run out of power capacity to fuel new ones, according to BroadGroup, the consultancy. In the US last year, data centre servers used as much power as TVs.

On the consumer side of the industry, activists are campaigning against the pollutants used to make gadgets. In February, Greenpeace, already active on the issue of recycling old computers, turned its attention to how new ones are built. A PC uses vast amounts of resources, “in terms of chemicals, energy and water demands” it said. Harmful solvents and heavy metals used to build devices with "clean images" such as mobile phones often make their way into water supplies, it found.

The good news, perhaps, is that environmental fears neatly align with self interests: as power prices escalate greener data centres become hugely cheaper to run; greener gadgets burnish their makers’ public images.

Apple, for instance, was recently stung when Greenpeace slammed its green credentials. That was especially vexing for Al Gore, perhaps the world's highest-profile environmental advocate, who sat on the Apple board. But it is also true that for many consumers, dirty manufacturing processes don't sit well with the clean white lines of an iPod.

As Gartner noted Greenpeace "has a long history of initiating debate that becomes mainstream opinion within a few years." Regulators, especially the EU, it added, are likely to take further action.

Technology tycoons are taking note. Michael Dell, chief executive of the world's second largest computer maker, recently pledged to blacklist suppliers who do not act to curb their environmental impacts. He was determeined to act before the regulators, he told Times Online.

Such remarks looked to have played a part in a domino effect. Intel, the largest chip maker and a key Dell supplier, last week joined Google in backing The Climate Savers Computing Initiative (CSCI). The CSCI's goal of making computers 50 per cent more power efficient by 2010, would "save" the amount of CO2 released by 11 million cars in a year, it said. Dell, IBM, Hewlett-Packard, and Microsoft are also on board.

But away from the press events, analysts argue that greener IT demands a radical shift in how businesses are run. Simon Mingay, of Gartner, says that positive momentum is building. But he adds that little action has yet been taken beyond what is mandatory. He points out that in many large companies, IT departments often have no idea what their electricity bill is, since it is paid for by Facilities.

Martin Hingley, chief research officer at IDC, agrees. "Power efficiency has seldom played a role in the computing industry," he said. "If anything we've been encouraged to use machines as much as we possibly can."

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