Just off the North Sea coast in the United Kingdom, Hewlett-Packard Co.'s EDS unit has built a data center that largely relies on cold sea air to keep servers chilled and -- by doing so -- cut the center's cooling power needs in half.
The expected reduction in electricity costs, from $15 million to $7.5 million, is achieved through a combination of factors that may begin with a 12-foot raised floor, which is easily three to four times the height of a typical data center raised floor.
The higher floor allowed designers to install fans 7.5 feet in diameter that bring in outside air to cool the 305,000 square-foot data center. The larger fans are more efficient than a series of smaller fans, said Ed Kettler, an EDS fellow. EDS is the HP division that is building the data center in Wynyard for its clients. "That is a relatively new approach as far as we can tell," he said.
The chilled air moves up from the pressurized raised floor through vents into a cold aisle between the server racks, and then is removed via the hot aisle. The outside cool air can be used virtually year-round, said Kettler. HP has set up a virtualized tour to show how this system works.
This use of free air cooling is part of an overall approach in data center design intended to capitalize on environmental conditions in data center building.
Google, for instance, has built a data center in The Dalles, Oregon, that uses hydroelectric power, and Microsoft has said that it intends to use outside air to help chill a massive data center in its building in Chicago. Data centers and servers account for more than 1.5% of all the electric power consumed in the U.S., which is more than all the electricity consumed by all the televisions in the U.S., the U.S. Environmental Protection said in a 2007 report on the power needs of IT.
Other steps taken by EDS to cut power use include painting server racks, which are typically gray, off white -- a far more reflective color that reduces the need for lighting. An intelligent lighting system that manages and focuses light where it is needed is also used.
In a data center in Tulsa, Okla., EDS took a different approach, building an 800,000-gallon water tank to help cool the facility. The water is chilled at night, which allows EDS to pay off-peak electric rates, and is used during the day to chill the facility. Asked what the return on investment is for this approach, Kettler said that "if the payback was more than three years we wouldn't be doing it.
