Blazing a Trail in Data Center Efficiency: UPS Windward Data Center Wins Green IT

Most people don’t think of websites, networks, and databases when they think “heavy industry”.

According to Joe Parrino, who heads the UPS Windward Data Center in Alpharetta Georgia, the rapid build-out of server farms and data centers is straining the grid in many parts of the country, especially in the Northeast. The IT industry is the sixth largest consumer of electricity, ahead of transportation, oil, and other decidedly heavy industries. I spent some time last week discussing the issues of data center efficiency and the work Parrino has done to make the Windward center one of the most efficient in the world.

Since the industry’s inception its primary goal, reflected in the charter mission of the Uptime Institute founded in 1993, has been and remains reliability – uptime. But the quest for rock-solid data centers left little room for resource efficiency, or even a reliable metric to adequately gauge that efficiency.

Feeding the beast

A survey of TechTarget members reported by shows that many data centers continue to relegate efficiency and environmental issues as a low priority. It’s about reliability and uptime, and if it takes more energy for more bandwidth, then feeding “the energy-consumption beast” by simply building new data centers remains the de facto strategy.

And it is a beast. A McKinsey report released earlier this year shows in stark terms how the current trend in the growth and energy consumption for data centers is rapidly becoming unsustainable. Energy costs are rising at an astonishing 16% per year. Greenhouse gas emissions from data centers already surpass that of Argentina.

Clearly there is more than reliability to be considered with the accelerating growth; the rush to build-out bandwidth without regard to the economic and environmental consequences of profligate and runaway energy consumption can’t be sustainable for very long.

Joe Parrino and his team at the Windward Data Center set out to find solutions and find ways to “tame the beast”.

PUE: A flawed metric is better than none

Effectively monitoring the energy flow through a data center is not a straightforward task. But it is something that Parrino and his colleagues set out to do in the 13–year-old Tier 4 Windward facility.

The primary metric available to Data Center operators is the PUE, or Power Usage Efficiency. The PUE measures the amount of power going into the facility as a ratio of the power arriving at the servers. The lower the number, the more efficient the facility. A 1–to-1 ratio would mean the for every watt of power going in, that full watt reaches the servers. That, of course, never happens. Parrino told me that the PUE metric was established only two or three years ago and, while flawed, is the best the industry has until a better way to measure data center efficiency is devised.

Plate heat exchanger for the UPS Windward Data CenterThe supporting infrastructure of a data center is the source of much of the inefficiencies, principally cooling and power redundancies.

Parrino achieves much of his efficiency in his cooling system. Windward was installed with two 1,000–ton centrifugal chillers and two 800–ton absorption chillers. There is also a 650,000 gallon thermal storage tank originally designed to provide 20 hours of backup cooling, but Parrino’s team employs a plate heat exchanger to cool the water in the storage tank using ambient nighttime outdoor temperatures.

The process is more complex than I need to go into here, involving wetbulb temperature and the like, but the upshot is that Parrino is able to shut down his 500 kilowatt chillers for up to seven months of the year, effectively providing the center with “free” cooling. In 2007 the chillers were shut down on October 11th and not turned back on again until May 18th of this year. The annual energy savings is about 1,440,000 kilowatts, eliminating 1000 tons of carbon emissions, and reducing energy costs by up to $100,000. All this in Georgia, where it gets hot. If more northerly data centers adopted Parrino’s innovative approach, the savings could be even greater.

Another source of efficiency gain Parrino found “by accident” was with the air handlers for the server power distribution units (PDU). Parrino’s team discovered several air flow inefficiencies with the air flow through the PDU’s. With modification Parrino is able to turn off 23 of the 65 air handler fans in the computer room, saving another 261 kilowatts of energy every hour and another $190,000 per year.

Parrino pointed out that these steps to efficiency are not only “green” but make business sense. Not only is there significantly lowered energy costs, but equipment life is extended and capital costs are reduced as well.

Once the PUE metric was established by the Uptime Institute Parrino decided to find out how his Windward facility stacked up against other data centers. When Parrino surveyed 15 other Tier 4 Data Centers, he found the average PUE was 2.43, with 31% of the incoming power in those centers used for mechanical cooling. By contrast the Windward center only uses 18% of its incoming power for mechanical cooling and other support systems. The PUE at Windward is 2.1 in summer and as low as 1.8 in winter.

From my half-hour chat with Parrino I could tell he was passionate about his work in managing the Windward Data Center. Tracking some 15 million packages a day across the globe obviously requires rock-solid reliability. Parrino shows that reliability need not be in lieu of efficiency. When asked the question he is modest, but specs show, as does Green IT Award Windward received, that Parrino and his team are indeed blazing a trail for other data centers to follow.


Tom is the founder, editor, and publisher of and the TDS Environmental Media Network. He has been a contributor for Triple Pundit since 2007. Tom has written for Slate, Earth911, the Pepsico Foundation, Cleantechnia, Planetsave, and many other sustainability-focused publications.