Wholesale data center provider Digital Realty has committed to spending an additional US$150m on a 400,000 sq m data center at its campus in Ashburn, Virginia campus in the US.

Digital Realty CEO Michael F Foust said sales tax exemptions from the Loudoun County have helped build demand at the campus, which already has four data centers on it, with the most recent breaking ground in May this year.

“This sales tax exemption is really a boon for our customers with data centers located in Loudoun County – already one of the most attractive data center markets in the country,” Foust said.

“The significant relief we and our customers expect to receive effectively lowers the total cost of ownership of our data centers in the area. We are very excited about this development and believe it further establishes Virginia as a key hub for companies seeking to locate or strengthen their east coast data center footprint.”

Details were not released about the new build, but the fourth data center, currently under construction, offers 214,000 sq ft of space for technical and other operations and can hold ten 1.125MW data center pods.

Digital Realty broke ground on the fourth facility after saying its other three data centers were almost fully leased.

The current investment will be used by 2015, Virginia Governor Bob McDonnell said, and will create 50 new jobs in the county.

The county has provided Digital Realty with a sales tax exemption for compute equipment eligible under legislation passed in 2009 by the General Assembly. It was issued in partnership with the Virginia Economic Development Partnership.

Chair of the Board of Supervisor’s Economic Development Committee Matt Letourneau said incentives such as the tax break add to the region’s strong fiber connectivity and low electricity rates to boost its appeal to data center operators.

“The Board of Supervisors has been focused since day one on expanding Loudoun’s commercial tax base, bringing jobs and revenue to our county,” Letourneau said.

Today, Loudoun has 5m sq ft data center space and another 3m is currently in development.

The first operator to break ground in Loudoun was Equinix. In FOCUS Issue 30 we speak with Jay Adelson, Equinix’s co-founder and one of the first to broker a deal with Loudoun County. The digital edition will be out later this week. Sign up on line for your copy.