Issue 10, June/July
FOCUS ASHRAE 90.1
The period for public review and comment of the addenda is closed however, leaving the ball entirely in ASHRAE’s court at this point.
EXTENDING ASHRAE’S REACH TO DATA CENTERS
The prospect of data centers coming under the purview of 90.1 appeared when ASHRAE decided to include thermal systems used during the manufacturing process in the document, which has traditionally been covering only systems for comfort cooling and heating.
“Computer room air conditioners never have been (included in the standard),” ASHRAE Mechanical Subcommittee Chair Drake Erbe said. “They’ve been able to do what they wanted to do. They now know that somebody else is watching, and helping, and they start paying attention even more to what they’re doing and take action on their own.”
A major impetus was the US Environmental Protection Agency’s 2007 report to US lawmakers that said the nation’s data centers were responsible for about 1.5 percent of total energy consumed in the US in 2006. The Report to Congress on Server and Data Center Energy Efficiency also forecasted that the amount of energy consumed by data centers would double by 2012.
Proposed changes to 90.1 represent ASHRAE’s approach to the issue. According to Montgomery, energy efficiency became one of ASHRAE’s key concerns in the mid 70’s, following the Arab oil embargo of 1973.
DETAILS OF GRAFTING COMPUTER ROOMS ONTO 90.1
So, what specifically would the two proposed addenda to the standard do if enacted in their current form?
Addendum ‘bu’ would set energy efficiency standards for cooling-system components. In relation to economizers, it responds to the need for adjustments of 90.1 “to accommodate the data center community,” Erbe said. “90.1 has many requirements for economizers. Addendum ‘bu’ more strictly outlines those areas where data centers need to be affected or (exempted), making sure that you don’t use economizers in a place where you shouldn’t but you do use economizers in areas where they’re justified.”
ASHRAE’s Standards Committee SSPC 90.1 is a separate committee from its Technical Committee TC 9.9 “Mission Critical Facilities, Technology Spaces, and Electronic Equipment”. The data center industry is most familiar with TC 9.9 and its work on raising the temperatures in data centers and publishing 9 data center books. The following are votes from TC 9.9 on this topic:
• Vote 1: TC9.9 Affirms Addendum AQ without the provisions of Addendum BU and Addendum BU ISC puts Data Center Industry in serious jeopardy.
• Vote 2: TC9.9 affirms exception k of Addendum BU ISC vital to ensure systems do not violate 90.1 paragraph 2.5
•• Vote 4: Do you agree that economizers should NOT be a prescriptive requirement? Vote 5: Do you agree with the blog message that the prescriptive approach stifles innovation?
Currently there is the possibility of Addendum AQ (incorporates data centers into 90.1) being approved without Addendum BU or with the wrong content of BU. This is one of the major areas of controversy.
First, ‘bu’ would add definition of a computer room to the standard’s language: “a room whose primary function is to house equipment for the processing and storage of electronic data and that has a design electronic data equipment power density exceeding 215 (watts per square meter) of conditioned floor area.”
The addendum then defines an “essential facility” for the purpose of exempting such facilities from the economizer requirement. Essential facilities include those serving things like hospitals, emergency services, power- generating stations, air-traffic control centers and national-defense facilities.
It adds a table to the document, defining energy-efficiency standards for computer- room air conditioners and condensing units. The addendum’s first draft expressed cooling capacities in Btu/h. The units were changed to kW after the industry commented on the first draft.
The addendum also makes a minor adjustment to efficiency requirements for dehumidification controls, which say they must prevent reheating, mixing of hot and cold air streams and simultaneous heating and cooling of the same airstream.
Finally, it sets a framework within which the existing economizer requirements will apply to computer rooms.
EACH COOLING SYSTEM THAT HAS A FAN…
“…shall include either an air or water
economizer…” the rule reads. It also lists 11 exceptions. The last two exceptions would be new. They list circumstances under which computer rooms would be exempted from the economizer requirement.
Exempted scenarios include “chillerless” systems of certain cooling loads or systems with chillers but also with very low cooling loads and local regulations among other factors. The aforementioned “essential” facilities are exempted as well.
An interesting exemption is that of facilities used for financial-transaction clearing and settlement services. This potentially exempts some colocation providers that serve the financial vertical. Some of their customers are companies that offer clearinghouse and settlement services. To fall under this exemption, they have to be processing only the largest-volume transactions and be integral to the overall financial system’s health.
The addendum would add two exceptions to the water-economizer requirement that directly address computer rooms. The existing requirement prescribes that such systems be able to cool air by indirect evaporation and provide up to full expected cooling load at outdoor air temperatures of 10C dry bulb/7C wet bulb and lower.
One exception is a computer room where an evaporative water economizer satisfies the entire cooling load at 4C dry bulb/2C wet bulb. Another is a room where dry cooler water economizers satisfy the entire load at 2C dry bulb.
www.datacenterdynamics.com 21
• Vote 3: TC9.9 affirms industry specific performance path is necessary to reduce data center energy consumption, commits to metric development.
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