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Data center experts push back on ASHRAE economizer requirements

An addendum to the ASHRAE 90.1-2010 energy standard could ease energy efficiency requirements on anyone building or significantly expanding data centers in the U.S.

Data center experts have proposed an alternative to a controversial provision of last year’s ASHRAE 90.1-2010 energy standard that would allow new data centers to be built without the mandatory use of economizers.

Under the original ASHRAE 90.1-2010 standard, data centers could be required to use an economizer, which uses outside air as a means of cooling the data center, despite the expense and difficulty of installing one in some locations. This would have profound implications for new data center build-outs.

“I think everyone in the industry would like to see an alternative compliance path, aiming towards a results-oriented rather than prescriptive requirement,” said Julius Neudorfer, CTO of North American Access Technologies Inc., which consults with organizations looking to build out data centers.

 The addendum, accepted by the American Society for Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) at last month’s winter meetings, would allow for an alternative means of satisfying the standard for energy efficiency using Power Usage Effectiveness (PUE) calculations. The addendum was created by a Working Group comprised of ASHRAE Technical Committee (TC) 9.9 members and 90.1 committee members.

Economizer requirement in experts’ crosshairs
The point of economizers is to reduce energy consumption, but it is not a good fit for every data center, especially where retrofitting existing buildings is concerned. Economizers can also be difficult to use in locations that are susceptible to droughts or where it is difficult to store large volumes of backup water. Using an economizer in a high-smog location can also cause server failures.

For those reasons, the 90.1-2010 energy standard drew fire from the data center industry last year when it included data centers for the first time and mandated the use of economizers in all but a few exceptions.

“The path taken by 90.1 was seen as being prescriptive, while the data center industry is very innovative and changes rapidly,” said Jack Glass, chairman of TC 9.9.

The addendum would give data center operators more freedom to design energy-efficient data centers as they see fit, including improving containment, advances in cooling systems like rear-door coolers or chiller plants designed for high-efficiency operation. New innovations are also on the horizon such as containerized data center designs that can run at highly elevated temperatures and negate much of the cooling challenge and cost.

Before it can officially become a part of the 90.1-2010 standard, the addendum must be fully vetted and then given final approval by other standards bodies including the Illuminating Engineering Society (IES), since the official standard is technically listed as American National Standards Institute (ANSI) / ASHRAE / IES Standard 90.1-2010, according to Don Beaty, president of DLB Associates, who originally proposed the addendum.

The ANSI process includes public review and then it must address public review commenters.

“There can be a wide variation in how many comments are received and how difficult those comments are to address,” Beaty said.

That public review process is expected to begin on March 23. 

Once approved, the addendum becomes available to the public, including each state.  The states can elect to adopt an addendum, reject an addendum or modify an addendum.

An ASHRAE spokeswoman said it would take about two to three years before states would review the newly published provisions.

 Beth Pariseau is a senior news writer for and Write to her at

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