David Quirk (DLB Associates), a speaker at this year’s Critical Facilities Summit, recently spoke with Energy Manager Today to discuss the changes happening to ASHRAE’s energy standards for data centers, including the differences between 90.1 and 90.4 From the article:
The Effort to Change ASHRAE’s Approach to Data Centers
An effort is underway to update an important standard for data center management.
ANSI/ASHRAE/IES Standard 90.1, the “Energy Standard for Buildings Except Low-Rise Residential Buildings,” dates back to 1975. The update – or, at least, one that energy managers are hoping for — comes in the form of Standard 90.4-2016, the“Energy Standard for Data Centers.”
ASHRAE 90.4 was published last month by ASHRAE. The biggest difference between the two is scope. Beyond that, ASHRAE 90.4 approaches data centers on a performance-based instead of in a prescriptive approach. In other words, it tells facilities what levels of performance data centers (or, in 90.1 parlance, “computer rooms”) must reach. It doesn’t, as in the case of ASHRAE 90.1, dictate precisely how those performance levels should be achieved.
ASHRAE 90.1 is a wide ranging standard. David Quirk, the Vice President and Principal of DLB Associates, said that ASHRAE 90.1 covers things such as insulation, lighting efficiency and requirements, HVAC efficiency and ratings of economizers and other “free cooling” technology.
Quirk, who is leading a panel on the conflicts between ASHRAE 90.1 and ASHRAE 90.4 at the Critical Facilities Summit this week in Charlotte, N.C., said that the biggest problem in ASHRAE 90.1 is that economizers – also known as heat exchangers – are mandated in data centers. These devices draw cool air, if it is available, from the outside environment to reduce the load on HVAC equipment.
The point is that data center cooling is so intense and vital that issues that are not challenges in less intense environments can be big problems. The other element is that data centers are mission-critical. An HVAC failure in the cafeteria may result in discomfort (and perhaps some sour milk); in the data center, it can be a threat to the well-being of the company.
Quirk maintains that the writers of ASHRAE were not data center cooling experts and the prescriptive demands on economizer operations were unrealistic. “They are risky, costly and dangerous,” Quirk told Energy Manager Today. “Data centers are all about uptime, availability and risk management “There had been a lot of experience [in which] economizers were difficult to control [and struggle to deal] with environmental issues such as contamination from outdoor air. There were a whole host of issues.”
John Bean, Schneider-Electric’s Director of Research and Development for Thermal Solutions, agrees that the lack of freedom in ASHRAE 90.1 is driving the new approach. “We are very supportive of 90.4,” he told Energy Manager Today. “We felt [ASHRAE 90.1] could stifle innovation because of its prescriptive nature.”
Quirk said that ASHRAE 90.1 dictates that economizers be used to reach the mandated power usage effectiveness (PUE). ASHRAE 90.4 separates the mechanical load component and electrical loss component (MLC and ELC). In other words, the ASHRAE 90.4 doesn’t tell energy managers that economizers must be part of the path to a designated design PUE. It tells them what level they need to reach and lets them figure it out. Energy managers and others are free to design systems that meet the standard’s requirement. Economizers may or may not be an element of the path that they choose to take, Quirk said.
The ASHRAE 90.1 committee can adopt ASHRAE 90.4 for data centers. It remains to be seen if that will happen. The key, according to Bean, is to broaden the potential paths for managing data center energy use. “We see people pushing things all the time that…may not fit precisely into the prescriptive language but have merit,” he said.
