Google has figured out a way to do it. And it is so simple. Locate your data center in a place like Belgium where you can use outside air as “free cooling.”
The concept of “free cooling” – bringing in outside air to cool the inside of a building -- is not new. Building managers in the US and elsewhere have been doing it for decades. By controlling dampers to balance the mix of inside and outside air, building managers can use the “free” outside air to better control temperature, humidity, and air pressure inside buildings without spending money on electricity.
Actually, all of us have done this at one time or another. Like on a Fall day when the sun hitting our windows makes it a little too warm inside, even though the air outside is cool. Instead of turning on the air-conditioning, we just open the window a little. Same concept. “Free” cooling.
All Google has done is take this very basic principle of facility energy management and apply it to complex data centers by adding a dash of information technology and off-shoring. The equipment in data centers generate a lot of heat. By locating them in a cooler climate and carefully managing the amount of cool fresh air coming into the building, Google can control the temperature without needing electricity to generate air-conditioning.
Belgium does have a few days per year (maybe about 7) when the outside air temperature is not cold enough to cool a data center. Google will monitor the weather and outside temperatures. If it gets too warm in Belgium, Google will simply shut down some equipment there (which will reduce the amount of heat being generated inside the data center) and shift some of the work load to other data centers around the world until the weather in Belgium returns to normal.
Now, in complex buildings like data centers, the cooling is not entirely "free." First, you need a building management system to monitor operating conditions inside the building and external data such as weather. Then you need to use the brainpower of facilities engineers to manage the system. But that little bit of data analysis and brainpower leads to tremendous reductions in both energy costs and carbon emissions.
Pretty good results for essentially opening windows.