Interxion Uses Sea Water to Cool Stockholm Data Centers

Interxion is no stranger to innovation. Over the years, the company has been pioneers in modular design, cold aisle containment, and now it is using seawater to cool a Stockholm data center, which is showing some serious benefits.

Jason Verge

March 6, 2013

6 Min Read
Interxion Uses Sea Water to Cool Stockholm Data Centers
Cabinets inside an Interxion data center. The company has just expanded in Stockholm and Vienna. (Photo: Interxion)




Cabinets inside an Interxion data center. (Photo: Interxion)


European data center provider Interxion is no stranger to innovation. Over the years, the company has been a pioneer in modular design and cold aisle containment, and is now using seawater to cool a Stockholm data center, generating some serious efficiency benefits. Energy costs have been reduced by 80 percent, the company said, slashing enough IT load to allow additional customers to colocate in the facility.

Interxion says the Power usage Effectiveness (PUE) for its Stockholm facility has dropped to 1.09, making it one of the most efficient data centers in Europe. The type of efficiency Interxion is experiencing in Stockholm is most commonly associated with facilities using air economization (free cooling) to leverage the cool environment in cool servers.

"We don't use outside air. We use chilled water, and we achieve 1.2 from this," said Lex Coors, VP data center technology for Interxion. "With the sea water we can achieve a PUE of 1.1 because we do not have to cool it over time. With sea water, you can take it in and push it out easily."

Mother Nature as Your Chiller

Seawater cooling systems pump deep, cold seawater through a data center’s HVAC system. As a result, the air circulating within a facility is cooled, which has the effect of lowering the inside temperature. Although the mechanics of this process are similar to chiller systems, seawater cooling completely eliminates the need to cool water down, which requires high levels of energy.

Interxion’s seawater cooling system is particularly notable because it runs water through multiple data centers multiple times, instead of the conventional strategy to run water through just one facility. This method also reduces operational and environmental costs, as it requires half the amount of water to cool each of the data centers. Interxion also doubles the use of seawater by reusing the warm water to heat local offices and residential buildings before returning it to the sea.

There are a number of techniques to tap external sources of cold water, effectively using Mother Earth as your chiller. But some work better than others, Coors said. He  noted the challenges of using deep lake cooling systems versus seawater and aquifers.

"With deep lake and aquifers there is basically a push back on using water," said Coors. "People are so afraid of legionella that they don’t use water power. We have to look for alternatives. There’s drilling into the ground, but that’s not allowed often. We can use sea water and salt aquifers."

Coors mentions there are advantages to working in Europe. “In Europe, we do not have to focus on the smart grid pipes, because basically if you are connected to a power grid in Europe, you’re connected to the national and international grid," he said. "It’s a matter of paying a little bit more and telling them 'I want this kind of green power."

So will seawater cooling, and its benefits, become a trend in the US? "Depending on the area, it should be a design trend," said Coors. “It really helps with the environment. If you have to run a pipe a mile, it’s still very beneficial. The Gulf is a bit hot, but in California there are enough opportunities."

A Track Record of Innovation

Interxion has a history of innovating; in addition to seawater cooling, the company has been pioneers in phased design and cold aisle containment. The company has been practicing phased construction in its data centers since 1999, a time when most data centers were being built as "barns" with large open floor plans being built in their entirety.

"We had to build data centers in 11 countries and only had a limited amount of capital available," said Coors. "I came from a ship company and took that idea of shipping containers back to the data centers. I didn’t want to build a bunch of data centers I’d have to upgrade in three to four ears. I did not install the whole infrastructure, nor did I build out the whole data center. Instead, we chopped the building into 4 phases of 10,000 square feet and installed infrastructure to support a limited capacity and over time, adding additional infrastructure to not interrupt operation.”


Coors says the company was also a pioneer in cold aisle containment.

“We brought it up in 2004,” said Coors. “It had nothing to do with energy efficiency (at the time), but had to do with a customer asking in his RFI for racks over 8 kilowatts. So we had to come up with an idea to support this. I came up with the idea to close the whole cold production to the servers. Later we found it had a big impact on energy efficiency.”

It was about that time that Oracle was first implementing containment in the U.S.

"Build out of necessity" is a mantra the company uses to drive its design innovation. Necessity means that a company strives for innovative approaches in order to achieve efficiency rather than throw money at a problem. “If you’re not afraid to step out of the box and share thoughts with people, they may laugh now and then,” said Coors. "But who cares? Sometimes you might hit the jackpot."

Interxion Reports Quarterly and Year-end Results

The company recently reported very solid 4th quarter and year end results. Revenue for the fourth quarter and full year increased by 13% to €72.9 million and €277.1 million, respectively, (4Q 2011: €64.4 million; FY 2011: €244.3 million)

Its equipped space increased by 4,400 square meters in Q4, as well as 11,200 square meters on the year for a total of 74,000 square meters. Revenue Generating Space increased by 5,000 square meters in the fourth quarter and 9,100 square meters for the full year to 56,200 square meters, for a total utilization rate across its footprint to 76%, up from 75% last year (a solid increase considering added space).Announced expansion projects remain on schedule.

Interxion Chief Executive Officer, David Ruberg, stated: “Interxion continued to execute in 2012, delivering strong financial results, despite a difficult macro environment.  We added record amounts of equipped space and revenue generating square metres, while increasing our utilisation rate.  Both revenue and adjusted EBITDA exhibited double digit growth, while positioning ourselves for continued growth into the future.”

Other examples of seawater cooling

Google is using cool sea water in the cooling system for its data center in Hamina, Finland (see a video of that data center). There’s also an innovative data center design in Helsinki that incorporates sea-water cooling and district heating. Helsinki Energy and IT service provider Academica built a data center for global IT outsourcer Atos that builds upon a design the two companies developed in a cavern underneath Helsinki’s historic Uspenski Cathedral.

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