News Brief

ASHRAE Drafts Energy Standard for Data Centers

December 30, 2013

Standard 90.4P for data centers will be performance-based and won’t require any modeling tools.

The mathematical models do not yet exist to appropriately predict data centers’ high plug loads and unique cooling needs, according to ASHRAE, so its new standard is based on PUE calculations.

Photo: Robert Scoble. License: CC BY 2.0.
Data centers have been running into roadblocks attempting to prove compliance to ASHRAE’s general energy standard, so ASHRAE is responding by developing Standard 90.4P—a separate standard for data centers that does not require modeling tools.

Until now, data centers had been included in ASHRAE Standard 90.1-2013, the energy standard for most buildings (aside from low-rise residential). However, demonstrating compliance with the energy costs budget section was difficult, according to ASHRAE, because current industry modeling tools cannot accurately model data centers’ complex HVAC and power distribution designs. In addition, changing IT technology and emerging cooling strategies have repeatedly transformed data center design, causing some to view the prescriptive measures in 90.1 as inflexible.

The new standard will have performance approaches for heating, ventilation, and air conditioning, and power distribution based on a measure of power usage effectiveness (PUE), which can be determined by using a set of formulas. Interior lighting allowance is calculated using the building area. Prescriptive measures in Standard 90.1 still apply to the building envelope and water heating systems, but a mechanical trade-off option is available for the building envelope. Overall, compliance with the standard will be based on predictive calculations and is not meant to require modeling tools.

Standard 90.4P will be open for public review until December 30, 2013.

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