When companies build "green" data centers, they usually do whatever they can to make the building, facilities, and computers more energy efficient. However, a European hosting company is taking things a step further in a new data center in London.

Telehouse Europe, a subsidiary of KDDI, announced last month that it will build a $120 million, nine-story, 200,000-square-foot co-location facility in London, on the site of the former docks of the East India Co., and that it's planning to use the excess heat generated by the data center to provide heat and hot water to neighboring homes and businesses.

According to Telehouse, the project, due to be complete by the middle of 2010, will be able to supply about 9 megawatts of power worth of heat energy to the neighborhood, saving local buildings about 2.5 million pounds of carbon dioxide annually, or enough energy to boil 3,000 kettles of water continuously all year long.

For the system to work, excess heat from data center computers will be pulled into a heat-recovery system and then forced through pipes to neighboring properties. The system to transfer the heat from the data center to nearby buildings is relatively inexpensive in the grand scheme of the $120 million data center, clocking in at just about $1.1 million, Bishop estimates.

The novel use of the data center's heat energy arose as engineering consultancy WSP Group, which is helping to build the data center, looked for ways to comply with London's increasingly stringent environmental laws. "As soon as you approach the planners on a project like this, they insist that you deal with energy and have a certain percentage of renewables," Martyn Bishop, senior technical director at WSP Buildings, said in an interview.

That said, there's some question of if or whether Telehouse will be able to take advantage of its system for a while. A nearby housing development project has stalled, neighboring buildings to which WSP had hoped to send excess heat turned out to be too far away, and another adjacent plot is empty.

This isn't the first time excess data center heat has been reused. An IBM data center in Zurich, Switzerland, is being used to heat a pool; researchers at the University of Notre Dame are using excess data center heat to make a greenhouse warmer; and both a Canadian media company and an Intel development center in Israel are using are using the excess heat for hot air to warm their offices.

Telehouse has long been conscious of sustainability. Other data centers it built in Paris and London were the first co-location facilities to meet an ISO standard for environmental management.