The Prineville data centre has an automated system of sensors that decide what mix of air should be presented to the servers. On cold days, outside air is mixed to cool down the servers inside. But on very cold days, outside air is something to avoid, as it tends to be dry and conducive to static electricity. On these days, the system takes air that has already gone through the servers, allows it to rise up into this mixing chamber to be re-used to warm the cold outside air coming in. Here you can see the moveable dampers regulating the mix of hot air coming up from the server room below (left) with the cold air coming from outside. It's from this room that this combination of air is mixed, filtered (right) and eventually returned to the server room. Photo: Steve Tague and Joseph Eastburn