Soaring data-crunching demands, coupled with energy shortfalls, have motivated companies worldwide to invest in new, green, state-of-the-art data centres.

Some organisations have limited their green practices to the inside of newly constructed facilities, embracing modular grow-with-demand designs, energy-efficient IT hardware, virtualisation, DC power, and smarter cooling technologies. Others, however, have taken eco-friendliness a step further by transforming pre-existing structures into data centres.

Today, we'll take a look at some of the more innovative and unusual facilities that companies have selected to house their datacenters.

It's the bomb

Thirty meters below central Stockholm, housed in a former nuclear bunker, resides a 1,100-square-meter state-of-the-art data centre. Owned by Bahnhof, one of Sweden's largest ISPs, the facility - dubbed Pionen White Mountains, a throwback to its military origins - more resembles the lair of a criminal mastermind from a James Bond flick than it does a data centre.

It also offers a level of physical security you won't find at most data centres: 16-inch-thick steel vault doors separate it from the rest of the world - and it can reportedly withstand a hydrogen bomb blast.

Pionen serves as the home of the NOC for all of Bahnof's operations and as a collocation hosting center. Among its specs is 1.5 megawatts of cooling for servers, courtesy of Baltimore Aircoil fans (enough to chill several hundred rack-mounted machines); triple network redundancy with both fiber optics and extra copper lines; and two German Maybach MTU diesel submarine engines providing backup power.

These aren't repurposed engines, mind you; they just happen to be the same model you'd find in the aforementioned submarine. For laughs, the company also installed submarine sound horns to serve as the facility's warning system.

In the interest of making the facility an enjoyable place to work, the designers including niceties such as simulated daylight, greenhouses, waterfalls -- and a 2,600-litre salt water fish tank.

Despite Banhof's decision to reuse an existing military facility for a practical business purpose, I don't honestly believe Pionen falls under the category of green data centre. Nothing about the data centre design suggests an efficient use of resources. Further, sub engines, fish tanks, and waterfalls lean more toward gimmicky than sustainability. To the company's credit, it doesn't trumpet the greenness of the facility either. You can take a guided video tour of the facility.

A nuclear fuel facility, reborn

Web-hosting company 1&1 is working on transforming a never-before-used nuclear fuel facility in Hanau, Germany, into a 100,000-server, 10,000-square-meter datacenter. The facility, called New MOX, was constructed in the late 1980s for the purpose of producing mixed oxide rods made from enriched uranium and plutonium. The facility never became operational, and by the end of 1995, its former owner Siemens AG decided to give up the space. Two years ago, the premises were finally released from nuclear control legislation, after which 1&1 acquired them.

Beyond putting a perfectly fine building to good reuse, the company has pledged that the datacenter operations will be green. For starters, like all 1&1 data centres, the facility will use electricity from only renewable energy sources. Moreover, 1&1 CEO Oliver Mauss says the facility will take advantage of outside air, also known as air-side economization or free cooling, to chill the data centre equipment. 1&1 uses low-energy components within all of its servers, according to Mauss.

Among its functions, the data centre will provide capacity for cloud computing.

New MOX is slated to open later this year.

Age is just a number

A 90-year-old former printing plant seems like an unlikely location for a 21st-century data centre, let alone a critically acclaimed green data centre.

Yet Digital Realty Trust, on behalf of an undisclosed Fortune 500 client, successfully transformed part of Chicago's R.R. Donnelly printing plant, built in 1917, into the world's first LEED (Leadership in Energy and Environmental Design) Gold-certified data centre.

The rating system, developed by the US Green Building Council, promotes a whole-building approach to sustainability by recognising performance in five key areas of human and environmental health: sustainable site development, water savings, energy efficiency, materials selection, and indoor environmental quality.

Located near The Loop, the 20,000-square-foot datacenter has raised-floor space with 4,000 kW of available IT load. Securing the LEED award required using as much of the existing facility as possible; it also took advanced commissioning, a process to ensure that all of its systems are designed, installed, and tested to perform according to the design intent and the building owner's operational needs.

Features of this particular project include sophisticated tools for measuring energy consumption, as well as equipment and a monitoring system that help improve performance of the ventilation system and indoor air quality.

Life after the military

The last thing you might expect to discover while tramping through the forest is a data centre. You will find one (if you know where to look) in the middle of the woods in Uitikon, outside Zurich. There, collocation provider GIB-Services and IBM partnered to transform a hidden, former underground military bunker into a highly secure, 360-square-meter data storage facility.

Beyond finding a smart reuse for a retired bunker, the partners devised a nifty, eco-friendly approach to putting the facility's 2,800 MWh of annual wasted heat: warming the nearby public pool for free. (The town did have to invest in hooking up the thermal transfer mechanisms.)

Out in the Open

Looking ahead, we may soon see companies opening up building-less data centres, with Microsoft leading the way. The company has already embraced self-contained "data centres in a box" at a facility in Chicago, cramming hundreds of containers into a 700,000-square-foot building.

The next step: foregoing a physical structure to house the containers altogether. The company's Generation 4 Modular Data Centre for its cloud computing infrastructure calls for containerised servers inside a secure perimeter with no roof. According to a New York Times blog entry, Microsoft says it can build a new data centre in about half the time if it doesn't bother with walls, a roof, and the like.