How a Snapshot of a Green Data Center Can Be Misleading

Grazed from GigaOM.  Author: Katie Fehrenbacher.

About a month ago, Facebook launched its Open Compute Project, which unveiled the nitty gritty of its energy-efficient data center in Oregon. The move is widely hailed as ground-breaking for an industry that keeps the location and size of its data centers top secret. But to me, Facebook’s touting of one specific efficiency metric shows just how a single snapshot of an energy-efficient data center can sometimes be misleading.

That efficiency metric I’m referring to is power usage effectiveness, or PUE, which looks at how efficiently a data center uses power and how much energy consumption is going to run its IT and servers. PUE rates data centers on a scale between one and two, with one being great and two not efficient. Think about it this way: If a lot of the data center’s energy is used for cooling and power conversion, the energy use is not very efficient and the data center will have a PUE closer to two; if very little of a data center’s energy is used for cooling and power conversion (and is instead mostly being used to power its servers), a data center is using energy much more efficiently and will have a PUE closer to one.

For Facebook’s data center in Oregon, the social network giant announced a PUE of 1.07 — one of the lowest I’ve heard about in the industry. But if you look behind the number, in actuality that number was just a snapshot of the data center in a prime energy-efficient state. The number was calculated over an eight-hour period during the data center’s commissioning stage. In an article on GigaOM Pro, I dig into why this is important.

Looking behind the scenes of the Facebook PUE number is critical because the Internet industry is only just starting to invest significantly into making its data centers far more energy efficient as a competitive advantage. According to the Environmental Protection Agency (EPA), data centers account for over 2 percent of energy consumption in the U.S.; that number is set to grow as more and more people buy up always-on gadgets and constantly connected computers. If an Internet company can cut its data center energy bill significantly, it can compete more effectively in the market by saving money, and also in smaller way, by being able to talk about its green ambitions.