Cold, hard data: Inside Facebook’s Swedish hub near the Arctic Circle

From the outside, it looks like an enormous grey warehouse. Inside, there is a hint of the movie Blade Runner: long cavernous corridors, spinning computer servers with flashing blue lights and the hum of giant fans. There is also a long perimeter fence. Is its job to thwart corporate spies? No - it keeps out the moose.

Welcome to the Node Pole, a hi-tech hub in Luleå, northern Sweden, and the site of Facebook’s first datacentre outside the US. The warehouse opened in 2013 and is set amid a green pine forest, lakes and an archipelago. The Arctic Circle is just down the road. A second centre next door is due to be completed later this year.

Facebook has four giant datacentres in the US, its newest at Fort Worth in Texas. Their construction is in response to the huge amounts of electronic data being generated around the world, at a rate that doubles roughly every 18 months.

In Facebook’s case, this means 350 million photographs a day, 4.5 billion likes and 10 billion messages. The chances are that if you upload a selfie in London, or post a status update in Paris, your data will be stored in Luleå, home to migrating reindeer and the northern lights. Pull up a 2008 photo and it will be conjured from a server here too, with data storage now a multi-billion dollar industry.

According to Facebook, its Luleå warehouse is the most energy efficient computing facility ever built. It is cold in the Node Pole: winter averages -20C. Freezing air from outside is pumped into the building. It acts as a natural coolant, with hot air generated by the servers circulating out. Walls of axial fans keep temperatures constant.