Technologies for Improving Power Usage Efficiency Ratings

Facebook Data Center in Prineville, Oregon

Located in a high-desert region, Prineville experiences an annual rainfall of just 10 inches and summer temperatures typically ranging from the 80s to 90s°F. Rather than traditional mechanical chillers and in-row cooling units, Facebook’s 147,000-square-foot data center relies entirely on an innovative combination of outside air and a MeeFog cooling and humidification system to maintain the temperature and humidity levels within the desired range for optimal server performance.

Setting the Standard for Energy Efficiency

In the pursuit of more efficient ways to dissipate heat from data center components, many companies use designs that focus cooling efforts directly on the racks or even the individual component in the rack, rather than controlling the entire room’s temperature. Facebook, however, took a contrasting approach: it optimized the temperature of the entire data center while completely eliminating fans within the racks and servers.

The facility was designed to operate at a steady 80.5°F, aligning with the ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) TC 9.9 Thermal Guidelines for Data Centers, and to maintain this temperature even when outdoor conditions reached 110°F—four degrees higher than Prineville’s record high over the last 50 years.

To achieve the desired result, a MeeFog system was designed consisting of 56 high-pressure fog pumps, each rated at 7.5 horsepower, capable of delivering 7.62 gallons per minute (gpm) at 1000 psi. These pumps, equipped with variable frequency drives (VFDs) for optimal energy efficiency, supply water through stainless steel tubing to arrays of impaction-pin nozzles. The nozzles atomize the water into an fine fog, which rapidly evaporates to cool the air and maintain the precise humidity levels required. Each of the facility’s 28 air handling units (AHUs) is served by two pumps—one on active duty, the other on standby—with automatic switchover to ensure uninterrupted service in the event of a failure.

The results were remarkable. Data center efficiency is commonly measured using the Power Utilization Effectiveness (PUE) rating, developed by the Green Grid consortium. PUE is calculated as the ratio of a data center’s total power consumption to the power consumed by its IT equipment, with an ideal score of 1.00 indicating that every watt of energy is going to the IT equipment.

Globally, data centers in 2015 typically achieved PUE scores between 2.0 and 2.5, while Google set an industry benchmark with an average PUE of 1.13. Facebook initially aimed for a PUE of 1.15 for its Prineville facility. However, during testing in December 2010, the data center achieved an astonishing PUE of 1.06. This meant that for every 100 watts of energy powering IT equipment, only 6 watts were used for cooling, lighting, UPS systems, and power distribution—a milestone in data center efficiency.

Telling The World

One of Facebook’s defining characteristics is making the world more open and connected, and the company extended this approach with its data center design. After launching its Prineville data center, Facebook announced the creation of the Open Compute Project(opencompute.org), an initiative to openly share all the server and data center specifications that contributed to Prineville’s success.

To kick off the Open Compute Project, Facebook hosted a tour of the Prineville data center, offering an in-depth look at the innovative technologies responsible for achieving its industry-leading low PUE. The data center features an entire floor devoted to pulling in the outside air, filtering it, cooling and humidifying it, and then sending it down to the floor where the servers are located. Notably, there is no ductwork in the data center, instead, a wall of high-efficiency 5-horsepower variable speed fans creates positive air pressure that drives cooled air into a 14-foot plenum above the cold aisles of the data center, minimizing the energy required by the server to pull the air past the components. On the upper air-handling deck, a series of louvers controls how much fresh air enters the building and how much hot air from the servers is either exhausted outside or recycled back through the system.

The MeeFog units play a critical role in maintaining optimal conditions year round. During the summer, the fog system cools the incoming air, while in winter, it is used to increase humidity levels to mitigate static electricity risks. This dual functionality ensures consistent performance and protection of sensitive IT equipment year-round.

Interested in learning more about how Meefog Systems is a solution to data center cooling? Click below to learn more.

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