Google’s data center in Belgium, which was the company’s first facility to rely entirely upon fresh air for cooling, instead of energy-hungry chillers.
…
For the vast majority of the year, the climate in Belgium is cool enough that this design works with no problems. When it gets hot in Belgium, the temperature inside Google’s data center warms beyond the facility’s desired operating range
…
During these periods, the temperature inside the data center can rise above 95 degrees.
…
“We’ve had very few excursion hours, and they don’t last long, so we let the site run right through them. We ask our employees to go in and do office work. It’s too warm for people, but the machines do just fine.”

Google’s experience is the latest affirmation that servers are much tougher than we think. Many data centers feel like meat lockers, as servers are maintained in cool environments to offset the heat thrown off by components inside the chassis. Typical temperature ranges in data centers often range from 68 and 72 degrees.

In recent years, rising power bills have prompted data center managers to try and reduce the amount of power used in cooling systems.