Hitachi Data Systems is working on what it claims will be the most power-efficient and eco-friendly enterprise-class data center in the world.

An addition to the company's Yokohama, Japan, data center has been designed to cut carbon emissions by 20 percent and achieve a 1.6 Power Usage Effectiveness (PUE) rating by The Green Grid, which would give it the lowest enterprise-class PUE rating, a metric that compares power used by the entire data center and power used by IT equipment within the building.

The completed wing, scheduled to be in production by April 2009, will feature water-cooled racks, uninterruptible power supply systems, power supply converters, virtualization and a rooftop garden to reduce energy, cooling and space needs.

Hitachi is adding about 116,000 square feet of floor to the almost 4.2 million square foot data center. Making one of the greenest data centers in the world is part of Hitachi's Harmonious Green Plan and Project CoolCenter50 initiatives. Through the two programs the company plans to cuts carbon emissions by 330,000 tons and reduce power consumption by as much as 50 percent by 2012.