The forecast for data centres isn't good for the short term: They're going to get hotter and a lot more cramped, according to Gartner analysts.

Increasing use of cheaper x86 chip-based servers has presented problems for data centres, most of which haven't been redesigned since the last tech boom went bust six years ago, said Gartner analyst Rakesh Kumar. He spoke today during a presentation at Gartner's Data Centre Technology Summit in London.

The number of server racks is increasing. Consequently, the amount of floor space per rack in data centres is decreasing even as their power and cooling requirements are rising.

More attention is being focused on the environmental impacts of running high-energy data centres and governments are moving toward new legislation. "It will come down to a balance between the power, the cooling and the floor space," Kumar said. "What that means is legacy data centres are obsolete."

Gartner predicts that, within 12 to 18 months, organisations will have to make major changes to accommodate the heating and cooling challenges that come with more processing power.

Four years ago, a stand-alone server in a rack used two kilowatts of electricity. Today, a standard rack that is 50 to 80 per cent filled with blade servers consumes between 15 kilowatts and 30 kilowatts, Kumar said.

The cooling statistics complicate the power picture. It takes between 1.2 to 1.3 times the amount of energy a server consumes to cool it, Kumar said. IT managers frequently can't fill an entire rack because of the heat generated by the servers.

Floor cooling systems, which circulate cool air under server racks, and air conditioning aren't going to work anymore because the heat is too great, Kumar said. What's more, the cool space beneath the servers in traditional data centres becomes clogged with cables and wires and, occasionally, other odd things that interfere.

"They're thinking, 'Hey, there's space under here. I'll keep my beer in there,'" said Peter Hannaford, of American Power Conversion, which makes server cooling equipment. "We found this guy who had a Christmas tree under there."

All of these obstacles contribute to higher energy costs. Gartner estimates that electricity costs could go from 10 per cent or less of IT budgets to 20 per cent to 30 per cent if left unchecked, Kumar said. Electricity costs have risen over the last year and will likely continue to rise, although the peak is unknown.

Fortunately, everyone from chip vendors to servers vendors and software makers has a stake in reducing energy and heat, Kumar said. The problem could ultimately limit the growth of IT. A huge amount of investment is being made in finding solutions, either through new products or through new data-centre designs.

Governments also are paying increased attention to IT. It's possible that governments could hit big consumers of power with higher taxes, or that some other legislation could be adopted, spurred by public demand for greener IT, said Steve Prentice, vice president and chief of research at Gartner.

"[The government] will rush something in that apparently does the job but does not address all the issues," Prentice said. "We think it's better to self-regulate."