Facebook Upgrades Outside Air Cooling System at Prineville Data Center

Data Centers

Prineville Data Center

Meta Platforms, Inc., dba Meta, and formerly named Facebook, Inc. operates 21 data center campuses worldwide to support its services, including operates Facebook, Instagram, Threads and WhatsApp among other products and services. These data centers represent an investment of $16 billion and span 40 million square feet. The company is at the front lines of data center innovation. Its Prineville site is its largest complex, which will encompass nearly 4.6 million square feet across about nine data centers once ongoing construction projects are completed.

Challenge

After helping Facebook design a highly efficient cooling and humidification system at the Prineville data center in 2011, the company wanted to boost efficiency even further and lower system maintenance requirements.

Solution

New pumps were recently introduced into the MeeFog system at Prineville along with system modifications to lower maintenance costs and improve Power Usage Effectiveness (PUE).

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The Physical Site:

The Prineville data center complex is in the high desert region of Oregon where the summer temperatures generally range between 80-90°F, with highs sometimes exceeding 100°F. The original data center was designed in 2011 to achieve the highest levels of efficiency. The 330,000 square feet facility boasts a PUE of 1.15, far above the industry average of around 1.6. That means that for every 100 watts going to the computing equipment, only 15 watts goes to cooling, lighting, UPS and power distribution.

Instead of using energy hogging CRAH units, Facebook utilizes outside air to minimize energy costs. The company decided to use one system to cool and humidify the entire building as well as the IT equipment racks. An upper floor is devoted to pulling in outside air, filtering it, cooling it and humidifying it before sending it down to the lower floor where the servers are located. No duct work is needed. Instead, the air handling system uses fans to create a positive air pressure in a plenum above the cold aisles. This minimizes the amount of work required at the server to pull the air past the components and keeps energy consumption low. The upper air handling deck has a series of louvers to control the amount of air pulled into the building and the amount of hot air from the servers that gets exhausted outside or recycled back through the servers. The original Prineville data center operates year-round without using mechanical cooling, even during the hottest summer days.

The Installation:

Facebook’s custom MeeFog system consists of more than 6,600 nozzles that provide the exact levels of cooling and humidification available in several stages. The original MeeFog system consisted of 56 x 7.5 HP positive displacement fog pump units from CAT Pumps, each with variable frequency drives. They provide 7.62 gpm of fogging at a pressure of 1000 psi. Two pumps are needed per air handling unit (AHU) (one active, another on standby). There are 28 AHUs in the data center. Pumps send water through stainless steel tubing to an array of specially designed impaction-pin nozzles which convert that water into a micro-fine fog that rapidly evaporates. The presence of fog in the air stream brings the air down to the desired temperature of 80.5°F in accordance with American Society for Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) standards.

As well as dealing with temperature, fogging also provides the desired level of humidity. The Prineville area is extremely dry. Rainfall averages 10 inches per year. Thus, low humidity could become a real problem for sensitive IT equipment due to the risk of static discharge. Adding moisture to the air courtesy of fog prevents static electricity from forming on the floor and on equipment. But you can’t add too much humidity. Otherwise, condensation may form, posing a further risk. Meefog keeps the humidity range in the required 45% to 55% range.

Recent Upgrades:

While the PUE of the original Prineville data center is impressive, the company strove to make further improvements. Facebook requested that Mee Industries find ways to make the system even easier to maintain. A new plan was hatched to take as much maintenance labor out of the equation as possible.

The original MeeFog cooling and humidification system used oil lubricated pumps. The presence of oil meant that the oil had to periodically be replaced, adding to the maintenance schedule. The oil-lubricated pumps were replaced with water-lubricated units from Danfoss Pumps to considerably reduce the maintenance burden and eliminate the need for regular oil changes. This entailed further modifications to the system to accommodate the new pumps. For example, the new pumps cannot slow down as well as the previous models and may sometimes pump more water than required. This can sometimes lead to the pumps heating up. Mee Industries added heat exchanger assemblies to all the pump skids to cool down the pump during low-load conditions.

As a result of these upgrades, the original data center at Prineville continues to meet the most stringent requirements for PUE and its fogging system requires almost no maintenance.

The Benefits of MeeFog technology:

The data center’s temperature is maintained at 80.5°F in accordance with ASHRAE standards. The data center operates year-round without using mechanical cooling, even when summer temperatures reach as high as 110°F. Fogging replaces traditional, refrigerant-based data center computer room air handling (CRAH) units. The facility achieves a Power Usage Effectiveness rating of 1.15, one of the highest in the world. Fogging keeps humidity between 45-55% to prevent static electricity from forming due to low humidity or condensation and rust formation due to high humidity.