Google’s data center in Hamina, Finland, was ranked third by Wired with a PUE of 1.14. According to Wired, Google has converted a 1950s-era paper mill into a state-of-the-art data center that uses seawater for cooling. Heat exchangers cool the servers, and the warm wastewater is mixed with seawater before it is returned to the Gulf of Finland, minimising thermal pollution.
The Finnish IT services company Tieto’s data center in Espoo was ranked seventh by Wired with a PUE of 1.2 to 1.3. The data center won the Uptime Institute 2011 Green Enterprise IT Beyond the Data Center award for using waste heat to heat 1,500 homes. According to Wired, the facility is located near a cogeneration power plant so that waste heat can be fed into the power company’s district heating network. The data center is expected to offset 10,000 tons of carbon dioxide.
Sources: IT Viikko, Wired