While it has designed its own servers and had original design manufacturers (ODMs) build them for its data centers, Facebook is using standard servers made by original equipment manufacturers (OEMs) in its Forest City, North Carolina, data center.

“We currently run OEM servers in our Forest City facility,” a Facebook spokesperson wrote in an email.

To maximize the use of free cooling in a humid climate, the facility’s operators keep server inlet air temperature well above the 80F standard operating limit in daytime during hottest days.

This meant that they did not have to turn the data center’s direct-expansion air conditioner on during periods of hot and humid weather, Daniel Lee, a Facebook mechanical engineer, wrote in a blog post. The facility is adequately cooled using a combination of outside-air and evaporative cooling.

In addition to showing it can be done in a warm and humid environment, Facebook’s success in running a 100% free-cooled data center in North Carolina also demonstrates that a company does not have to design its own servers to run a data center hotter than the standard temperature recommended by the American Society of Heating and Air Conditioning Engineers (ASHRAE), whose recommendations are de facto industry standards.

“One of the encouraging things about the data we released today is that it suggests it is possible to rethink some of the standards that have been put into place surrounding the maximum heat and humidity for a server environment,” the company spokesperson wrote.

The Forest City facility is the only data center Facebook owns and operates that has a back-up direct-expansion cooling system for the days when free cooling just will not cut it. Its other two facilities in Prineville, Oregon, and Lulea, Sweden, rely fully on outside air and evaporative cooling.

While it is encouraging that raising temperature in the data center above the norm can work with standard servers, networking equipment is another story. Jay Park, Facebook’s director of engineering, said networking gear starts “misbehaving” at 85F.

“The Achilles heel in the data center is networking,” Park said Wednesday during his presentation at the DatacenterDynamics Converged conference in London.