A day after leading data center builders criticized proposed changes to guidelines on data center cooling, an HVAC industry group says their concerns have already been addressed. The Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) said the proposed changes would not force data center builders to use fresh air cooling in new facilities, but will leave room for companies to use other approaches.
The dispute erupted after a proposed change to ASHRAE Standard 90.1, a key guideline for local building officials across the U.S. The change would recommend that outside air economizers be used to cool data centers. This approach, also known as free cooling, allows data center operators to save money by using fresh air to cool server rooms, rather than relying upon chillers that use large amounts of energy.
Leading executives from Google, Microsoft, Amazon, Digital Realty Trust, DuPont Fabros Technology and Nokia signed a joint letter urging ASHRAE to avoid prescribing a specific approach as the preferred method for cooling data centers. They called on ASHRAE to instead adopt an overall efficiency standard for data center cooling, focusing on results rather than methodology.
ASHRAE, in an e-mail statement, said the standard will include options for companies that opt for approaches other than economizers.
"The proposal to address data centers was made because a significant amount of energy is required to cool and ventilate computer rooms," the group wrote in its statement. "Through this addendum, ASHRAE is proposing cost effective measures in the prescriptive path of Standard 90.1 to save energy in data centers. The addendum includes eight exceptions to requirements for the use of economizers in data centers. The addendum does not change the portion of the standard that already allows, through the Energy Cost Budget method (an alternate method of compliance), for data centers to be designed without economizers if other energy saving methodologies, including power usage effectiveness (PUE), are employed."
So is the issue settled? Public comment on the proposed changes remains open through April 19. It's clear that major data center builders will continue to press for adjustments to the Standard 90.1 to remove any prescriptive recommendation for data center cooling. A key concern is how the standard will be interpreted by local building officials, who may not always be well versed in alternate compliance methods.
Chris Malone, a Thermal Technologies Architect at Google, said data center operators welcomes the focus on efficiency, but want to retain the flexibility to innovate and develop new approaches to cooling. He said that Google uses economizers extensively (see Google's Chiller-less Data Center for details) but noted that the emergence of fresh air cooling is itself an indication of the speed with which best practices can change.
"Not so long ago, economizers were a taboo subject for data center operators," said Malone. "Who knows what data center cooling system will look like in the future. There may be technologies on the horizon that might not require. Many in the industry would argue that an alternative path needs to be available."
The global acceptance of Power Usage Effectiveness (PUE) is promising, but Malone said that PUE tracks energy efficiency for a facility, rather than just the cooling system. He said Google and the other signers of Monday's statement feel strongly about the ASHRAE proposal and its potential impact.
"We thought it was important to take a public stance," he said, adding that the companies involved "represent a good fraction of the innovative data center builders."
ASHRAE, for its part, says it welcomes the feedback on the proposed changes. "ASHRAE is committed to excellence in the consensus standard development process and encourages anyone with comments regarding the proposed addendum regarding data centers (addendum bu) to participate in the public review process," it said.