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Until there is a standard method of PUE calculation, ask what goes into claims for superior PUE performance.
If you are interested in data center design or performance, you've undoubtedly been seeing sales sheets, white papers, and news reports of products and techniques for increasing data center energy efficiency.
The metric most often quoted in data center power use efficiency is Power Use Effectiveness (PUE) and its inverse, Data Center Infrastructure Efficiency (DCIE). PUE and DCIE compare the data center facility's overall power consumption to the power consumed by the information and communication technology (ICT) equipment. These metrics, which are primarily facilities-based, will probably serve as the framework for a future standard; however, they are still being developed. Whether or not the metrics are being used prematurely depends on how they are being used (i.e., for self-promotion or for encouraging discussion), and if the testing procedures or simulation algorithms are disclosed.
Until a formal, recognized standard with a rigorous, engineering-based process to judge data center energy efficiency is developed, presented for public review, and formally adopted by a widespread consensus, published efficiency ratings will continue to be based on the interpretation of those who report the figures.
The good news is that there already exist some established energy standards, such as ANSI/ASHRAE/IESNA Standard 90.1-2007, Energy Standard for Buildings Except Low-Rise Residential Buildings, for other areas of the building that impact the data center's efficiency (see Figure 1). This article examines these interdependencies, enabling designers, owners, and facility decision makers to ask tough questions when faced with new construction and renovation projects for data centers.
BUILDING ENVELOPE
Relative to the energy required to cool and power ICT equipment, the energy impact from the building envelope is small. However, the importance of code compliance and the effects of moisture migration cannot be overlooked.
For data centers, the integrity of the building's vapor barrier is extremely important, as it safeguards against air leakage caused by the forces of wind and differential air pressure. It also minimizes migration of moisture driven by differential vapor pressure. Most data center cooling equipment is designed for sensible cooling only (no moisture removal from the air). Higher than expected moisture levels in the data center will result in greater energy consumption and possible...