In another one of those special posts on the Wikibon blog the research foundation looks into the seven most eco-friendly facilities out there. The green data center trend is picking up, thanks to vendor recognition from IBM and other hardware giants, along with adoption on behalf of some of the industry’s biggest names – from Facebook to Google, and Hewlett-Packard as well.

First up is Yahoo. The web portal uses natural air cooling in its Niagara County, NY center to reduce the amount of energy that goes into keeping its servers nice and cool; about one percent of the electricity used.

The approaches companies take to maintaining their servers’ temperature  are only getting more original as we go further down the list. Facebook has decided to take Greenpeace’s hint and set up one of its server farms in Sweden, currently powered by hydroelectric power and cooled by the region’s naturally cold climate. This is similar to what Google did with an old Finnish paper mill, which is no surprise considering the search giant’s chief green architect migrated to Facebook last year.

While some resort to air and sea-water, Apple decided to take the solar panel route. Far more innovative though is the Pionen data center situated in Sweden – 100 feet underground inside an old nuclear shelter,  an environment that makes the resident techies much easier to maintain thanks to a constantly low climate.

Finally it’s time to talk a bit about Hewlett-Packard. It’s working on setting up a new facility for Nordic real-estate firm Entra, and it’s going to be one of the biggest one of its kind.  As HP moves further into the data center business, eco-friendly considerations are of great importance to their long term goals.