Managed cloud provider Rackspace has opened its new 6MW data center in Crawley, south of London, built by Digital Realty and using only outside air for cooling. The design has been shared with the Open Compute Project .

The data center is the first at this scale to be built in the UK without any mechanical chillers, says Rackspace, and is designed to have a PUE (power usage effectiveness) of 1.15. Two of its four data halls are open - and Rackspace showed visitors round on April 22 before beginning to install equipment for customers. 

The air is fresh and sweet (up on the roof)

To save space, and build an efficient vertical flow of power and air, Rackspace and Digital Realty have put all the power and cooling systems on the roof. The physical layout and design idea will be shared with the Open Compute Project, making it freely available to other data center builders, Rackspace announced at the launch. 

The cooling units on the roof are from Excool, using indirect outside air or “free” cooling, taking in air to circulate through a closed loop system based on contained hot aisles. When the air temperature is warm, the Excool units add in evaporative cooling, with a water spray system.

This allows the site to operate without mechanical chillers, reducing its energy usage. Water for the evaporative cooling system will be harvested from the building’s roof to further reduce environmental impact. 

The power distribution system uses Emerson units, and a conventional battery-backed UPS with conversion to direct current on the roof and back to AC for distribution to the racks. High voltage DC distribution was considered but it still requires a lot of conversions, Digital Realty staff explained to DatacenterDynamics.

The building has a BREEAM “excellent” rating, and supports the latest (2011) ASHRAE guidelines. It is based on contained hot aisles which rest on a solid concrete floor. The air inside the building is at 24C and the hot aisles are at 36C.

Open Compute 

The design is based on the Open Compute Project’s principles, with less weight, waste and power requirements, although the site can accommodate both Open Compute racks and conventional systems. At capacity it can hold 50,000 physical servers, and its current 6MW capacity can be extended to 12MW.

The site extends an ongoing Digital Realty and Rackspace partnership onto a third continent, said William Stein, Digital Realty’s CEO: ”We are delighted to see Rackspace establish its new managed cloud data centre with such outstanding eco-credentials. With competition growing for facility services across the UK and Europe, we are pleased Rackspace choose Digital Realty as a provider to collaborate on this bespoke facility in Crawley.”

The ribbon was cut by local Conservative MP Henry Smith, who has visited the project during its genesis, and is currently standing in the UK’s General Election. ”I fully understand PUE,” quipped Smith,” and if I am not re-elected in May, I will be sending my CV to Rackspace.”