ASHRAE has announced the publication of ANSI/ASHRAE Standard 90.4-2016, Energy Standard for Data Centers. The standard establishes the minimum energy efficiency requirements of data centers for design and construction, for creation of a plan for operation and maintenance, and for utilization of on-site or off-site renewable energy resources.
“We worked very hard to craft this standard in a manner that does not stifle innovation in the data center industry while simultaneously offering criteria to help ensure energy savings,” said Ron Jarnagin, chair of the 90.4 committee. “It is important to keep in mind that data centers are mission critical facilities where risk management is the primary concern.”
Jarnagin noted that high plug loads and rapidly advancing IT technology make data center applications significantly different from their commercial building counterparts. Standard 90.4 specifically addresses the unique energy requirements of data centers.
According to ASHRAE, Standard 90.4 is a performance-based design standard that offers the design components for mechanical load (MLC) and electrical loss (ELC). Calculations of the MLC and ELC are made and then compared to the maximum allowable values shown in the standard based on climate zones. Compliance with Standard 90.4 is achieved when the calculated values do not exceed the values contained in the standard. An alternative compliance path is provided that allows tradeoffs between the MLC and ELC.
“The committee initially pursued a Green Grid power use effectiveness-like (PUE) process for setting the criteria in the standard but the Green Grid’s PUE metric is actually based on measured energy use data rather than design criteria calculations,” Jarnagin said. “We realized that the design calculations contained in Standard 90.4 would not likely match up with the actual energy use data so this approach was amended. We feel that we’ve recommended the requirements for 90.4 based on a justifiable 80/20 rule where only the lower performing systems will be affected.”
The Standards Committee, which has oversight of all ASHRAE standards, will work together with the chairs of Standard 90.4 and ANSI/ASHRAE/IES Standard 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, to remove data centers from Standard 90.1. Standard 90.4 already refers users to Standard 90.1 for requirements on lighting, service water heating, and the building envelope.
Other requirements in Standard 90.4 include:
• A sample compliance checklist
• Diagrams to illustrate compliance
• Sample calculations
Jarnagin noted that industry input is vital as the standard moves forward. The standard now is under a continuous maintenance process that allows changes to the standard to be made on a continuous basis through the mechanism of addenda to the standard. This process will allow for frequent changes to the standard as needed to keep pace with the rapidly changing technologies in the industry, he said.
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