Gartner's 27th annual data center conference is producing no shortage of research related to energy consumption, virtualization, cloud computing and other hot enterprise topics. Here are some of the most interesting numbers revealed by Gartner research and polls of conference attendees.

Forty-two percent of IT professionals polled at the Gartner conference operate three or more data centers in North America.

Forty-five percent are expanding or planning to expand data centers in the next two years, while 43% are consolidating. 

A standard 9,000 square foot, Tier 3 data center that supports 150 watts per square foot will cost approximately $21.3 million to build, with $1 million in annual electrical costs. 

Green IT practices that minimize use of chiller plants, fans and pumps, lighting and power supplies can more than halve the power costs of running a data center.

An aggressively "green" enterprise will pay $560,000 in annual electrical expenses for a data center with a 500 kilowatt IT load. Enterprises with archaic data center practices will pay as much as $1.3 million.

In a conventional data center, 35% to 50% of electrical energy is devoted to cooling. With best practices, that proportion is reduced to 15%.

Twenty-six percent of conference attendees buy green products only when they lower costs, save space or defer data center construction. Thirty-four percent will buy green products even if they increase costs.

Storage spending is growing almost three times faster than the IT budget as a whole. From 2007 to 2011, storage spending will increase more than 7% a year, compared with annual IT budget growth of only 2.5%.

By 2012, users will install 6.5 times the amount of terabytes they installed in 2008.

Server virtualization, one of the key technologies driving costs down in data centers, is suitable for about 70% of workloads.

Today, only 12% of x86 server workloads are running in virtual machines. By 2013 that number will be 61%.

One out of every four x86 workloads deployed or redeployed in 2008 is being installed in a virtual machine. Still, vendor licensing, pricing and support plans are limiting virtualization efforts, according to 21% of conference attendees.

About 70% of virtual machines today are used in production. Just a few years ago, most were used only in test and development roles.