The ASHRAE Data Center Weather Report

Julius Neudorfer
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) announced that the climate in data centers is going to be warmer as it expands the recommended environmental envelope to improve energy efficiency. In fact, in what would have been considered heresy just a few years ago, it is envisioning and advocating the more common use of non-mechanical (compressor-less) cooling-so called 'free cooling'-economizers using ambient air temperatures (within limits) to cool the data center.

The details of the expanded temperature and humidity ranges are going to be released in the soon-to-be-published third edition of the ASHRAE datacom book, 'Thermal Guidelines for Data Processing Environments.'

According to Don Beaty, chair of the Publications Subcommittee of ASHRAE's Technical Committee (TC) 9.9, Mission Critical Facilities, Technology Spaces and Electronic Equipment: The approach used by TC 9.9 for the first edition through to the present was to assemble a team of thermal engineers from the major commercial IT manufacturers to develop requirements. The first edition created a recommended temperature upper limit of 77  F (25 C), promoting the use of higher temperatures and endorsed by all of the IT manufacturers.

The second edition (2008) took considerable deliberation amongst the manufacturers and raised the recommended upper limit to 81 F (27 C). Both the first and second editions were groundbreaking (the first edition in unifying the industry and the second edition in enabling the potential to use economizers in many locations and applications).

Beaty says the third edition will be equally groundbreaking in that it will enable compressorless cooling (all cooling through economizers) in many applications. Accomplishing this has been a challenge since major tradeoffs (equipment size, equipment cost and operating cost) surface above a certain temperature threshold. This challenge is complicated because the threshold is not the same for all the manufacturers.

Beaty will be presenting the details of the third edition at the DataCenterDynamics conference in New York on March 10th, along with Jack Glass, senior vice president, ASHRAE TC 9.9 vice chairman for Citigroup and Roger Schmidt, distinguished engineer, ASHRAE TC 9.9 for IBM.

According to a February 17th ASHRAE press release there will also be several options regarding the type of IT equipment to be used in the data center. Just as a note, there have always been two general classifications for some types of IT gear, the commercial systems that are in common use in the data center, which is generally rated at up to 95 F by most of the IT manufacturers, and the Network Equipment Building System (NEBS) rated versions of some equipment that are used primarily by the telecomm industry for use in harsher environmental conditions and can tolerate a much wider temperature an humidity range.

From the ASHRAE press release:

From an end user perspective, it is also important that they be provided with options for their multi-vendor facilities such as:
. Option 1-use IT equipment optimized for a combination of attributes including energy efficiency but the dominant attribute being capital cost.
. Option 2 - use IT equipment optimized for a combination of attributes including some level of reliability but the dominant attribute being energy and compressorless cooling.
The industry needs both types of equipment but also needs to avoid Option 2 increasing the cost of Option 1 by increasing manufacturing costs through mandatory requirements not desired or used by all end users. Expanding the temperature and humidity ranges can increase the physical size of the IT equipment (e.g. more heat transfer area required), increase IT equipment air flow, etc. This can impact embedded energy cost and IT equipment cost.

This new ASHRAE 'Options' classification for equipment seems to indicate that there could potentially be two types of IT gear for the data center, in which 'Option 2' equipment may cost more initially, but would presumably offer cost recovery via energy savings by operating at higher temperatures. This Options classification is different and in addition to the already existing Class-1 and Class-2 environmental envelopes, already defined under the existing ASHRAE 9.9 classifications.

The Bottom Line

This upcoming third edition will go further along the path of loosening the rigid rules of 68-70 F that dominated the industry until the 2008 release of the second edition of ASHRAE 9.9, which allowed the 'recommended' Class-1 temperature to go to 80.6 F (27 C).

In the two and a half years since that release, even mainstream enterprise data centers have gradually been allowing temperatures to slowly rise (at least into the mid 70's). Moreover, some of the leading edge missionaries such as Yahoo's 'Chicken Coop' data center have already gone much further, by designing and building sites with no mechanical cooling. So as I have previously prognosticated, cold aisles will become warmer and hot aisles hotter, as even mainstream data center operators move to become more energy efficient by adopting ASHRAE's 9.9 newest recommendations.

Fashion outlook for IT: Hawaiian shirts and Bermuda shorts.

Add Comment      Leave a comment on this blog post
May 18, 2011 7:05 PM Joanna Joanna  says:
Aside from the fact that it's a joy to spend an hour on a data hall floor without afterwards being treated for hypothermia, I think this development is great news. Maybe there really will be such a thing as a "green data center" in the near term? Joanna Reply
Feb 2, 2012 9:02 AM short prom dresses short prom dresses  says:
We really need to understand these things! Reply

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