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ASHRAE okays hotter data centers

Under ASHRAE TC 9.9’s new recommendations, operators can increase data center operating temperatures -- and decrease their reliance on computer room air conditioners.

This news article is part of's coverage of the Uptime Institute Symposium. Read more related content and news from this event: Uptime Institute Symposium 2011 coverage.

SANTA CLARA, CALIF. -- A key player in the data center industry has given the nod to higher data center operating temperatures, making it possible to turn down -- or turn off -- power-hungry air conditioners..

In a new white paper on thermal guidelines for data processing environments, the American Society for Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Technical Committee 9.9 described two new classes of data center equipment for which the maximum allowable temperature range is now 41 to 113°F (5 to 45°C).

That’s a huge increase over ASHRAE’s old recommended levels set in 2008, which list the maximum allowable temperatures at 59 to 89.6°F.

ASHRAE’s new recommendations are already commonplace in new data centers, said Vello Ehvert, principal engineer at Ehvert Engineering, a data center consulting firm in Toronto, but data center managers will be happy to have ASHRAE’s blessing.

Raising a data center’s operating temperature constitutes “real money,” Ehvert said, often translating to hundreds of thousands, or even millions, of dollars in energy savings. But some data center managers shy away from higher data center operating temperatures for fear of running afoul of vendor warranties.

System OEMs sign off
To arrive at this expanded temperature range, ASHRAE TC 9.9 created new classes of data center equipment with lowered reliability -- as is often the result after prolonged exposure to higher temperatures.

Specifically, ASHRAE’s old Class A and Class B designations have been renamed A1 and A2, and refer to equipment that goes into highly regulated, mission-critical data centers. The new Class A3 and A4 equipment, meanwhile, is usually destined for “an information technology space or office or lab environment with some control of environmental parameters (dew point, temperature, and relative humidity).”

In practice, Class A3 and A4 equipment will probably have a short refresh cycle of two to three years, rather than the six to nine years expected of A1 and A2 equipment, said Don Beaty, president of DLB Associates and former ASHRAE TC 9.9 chair, in a session at the Uptime Institute Symposium on Tuesday. “The longer the lifetime, the more the consequences of being outside that [temperature] range,” he said.

When it comes to raising temperatures, “data center managers worry about two things -- ‘Did I cause an expensive outage? and ‘Did I just void the warranty on some very expensive IT equipment?’” said DLB’s Beaty.

Thus, ASHRAE’s recommendations aren’t significant in and of themselves, but because they signal that server and storage OEMs have signed off on them, Ehvert said.

Free cooling on tap
ASHRAE’s blessing for higher operating temperatures means an expanded role for air-side ecomizers, also known as “free cooling,” experts said.

An ASHRAE analysis of average U.S. and European temperatures show that the average temperatures are at or below ASHRAE’s new temperature range to be able to use outside air most of the year, Beaty said. That limits the use of chillers to the hottest summer days.

Using outside air and economizers can significantly reduce data center energy costs, said Chris Malone, Google’s thermal technologies architect. He said raising temperatures and using economizers were key ways Google improved data center cooling and boosted its energy efficiency.

“ASHRAE’s extended temperature ranges,” Malone said, “are a great step in enabling economizers to be used more broadly.”

This news article is part of's coverage of the Uptime Institute Symposium. Read more related content and news from this event: Uptime Institute Symposium 2011 coverage.

Let us know what you think about the story; email Alex Barrett, News Director at, or follow @aebarrett on twitter.

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