mixing of the air or there might be ar-
eas where it’s leaking.”
In one case, Synapsense in-
stalled 3,674 sensors throughout a
Those vanity plates are only one
problem with standard hardware. “If
you take a standard off-the-shelf server
there are probably quite a few things
that need to be improved to have it
work more efficiently,” says Bianca
Schroeder, a computer scientist at
the University of Toronto and the co-
author of a recent paper on data cen-
ter efficiency (see the Further Reading
list). For example, Schroeder notes

Ambient air flows through Facebook’s data center in Prineville, oR, and cools the servers inside the 334,000-square-foot facilty.

 

chanical chillers at all. “We don’t need them,” says Weihl, who was previously Google’s energy efficiency czar.

At Facebook’s Prineville facility, ambient air flows into the building, passing first through a series of filters to remove bugs, dust, and other contaminants, then into a long corridor. On hot days, when the outside temperature rises above 80 degrees Fahrenheit, the air moves through a fine mist of micron-sized droplets of water suspended in the corridor. Some of the mist evaporates on contact with the warmer outside air. This reduces the temperature, and the mildly chilled air then passes through another filter, which captures the droplets of water that did not evaporate. The end result is a rush of cool air flowing into the building.

PhotograPh by ChuCk goolsbee

When it is too cold outside, the control system automatically mixes in some of the 85 to 90 degree Fahrenheit air coming out of the back of the servers to bring it up to the right temperature. “We don’t want 20 degree Fahrenheit air going into our servers,” Weihl says. Drastic changes in temperature could cause components to expand and contract, creating mechanical stresses that might lead to permanent damage.

problem. Companies have also begun demonstrating the importance of managing circulation within the space. When Synapsense audits a facility, its technicians install wireless sensors throughout the building to measure temperature, pressure, humidity, and more. Pandey says Synapsense often identifies intense hot spots—warmer areas that force the fans and mechanical chillers to work harder to manipulate the temperature, thus increasing energy usage. “You might have enough cool air, but it’s not going to the right places,” he explains. “There might be

the most efficient
data centers
now hover at
temperatures
closer to 80 degrees
Fahrenheit, and
instead of sweaters,
the technicians walk
around in shorts.

Smart monitoring

The source of the cool air in traditional data centers is only part of the