New energy standard for data centres needed

ASHRAE is proposing a new standard for energy use in data centres. ASHRAE Standard 90.4P, Energy Standard for Data Centers and Telecommunications Buildings would establish the minimum energy efficiency requirements of data centres and telecommunications buildings, applied to their design and construction, for creating a plan for their operation and maintenance, and for their using on-site or off-site renewable energy resources.

Ron Jarnagin, chair of the Standard 90.4 committee said, “There is no intent to duplicate what is contained in Standard 90.1, but rather we are proposing criteria to support the specialized nature of the larger data centres. When adopted, design and construction of data centres will require the use of both Standards 90.1 and 90.4 for compliance with building codes.”

David Quirk, chair of ASHRAE’s Technical Committee 9.9, Mission Critical Facilities, Technology Spaces and Electronic Equipment, noted that the intent of Standard 90.4P is to create a performance based approach that would be more flexible and accommodating of innovative change, which can occur rapidly in data centre design, construction and operation.

Data centre applications are unlike their commercial building counterparts in two ways, Quirk noted. First, they include significantly higher plug loads. And second, they use rapidly changing technology for the IT equipment and associated power/cooling approaches.

“It has been acknowledged that these differences drive a fundamentally different approach to regulating minimum efficiency requirements for the electrical and mechanical systems that support the plug loads,” Quirk said. “By using an approach that requires compliance to a ‘system’ level of performance, designers and end-users can utilize various trade-offs in their optimization strategizes depending on their company specific business models.”

According to Jarnagin, current industry modeling tools do not possess all the necessary mathematical models to accurately and appropriately model data centre HVAC and power design. As a result, demonstrating compliance to the 90.1 Chapter 11 or energy cost budget (ECB) approaches was deemed impractical.

This standard is based on the principles of power use effectiveness (PUE), as defined by The Green Grid. However, because PUE is an operational measurement metric, and this is a design standard, PUE terminology is not a technically accurate usage. The committee recognizes that language needs to be developed to relate the calculations of energy efficiency set forth in this standard to a total efficiency number, as well as to allow tradeoffs between electrical and mechanical elements. Suggestions from reviewers as to how best to accomplish this are welcome, he said.

Jarnagin also said the two committees are aware of some potential conflicts between the definitions of computer rooms and data centres in the standards. The intent is to address those conflicts once Standard 90.4 is approved and published.