Micro PUE is calculated by measuring energy efficiency at the cooling component level, allowing data center managers to view each cooling unit’s efficiency versus other units. The cooling unit results show exactly where energy loss occurs in the data center.
”We wanted to show that it was possible to accurately measure and manage each cooling unit, by gathering heat data in BTUs and relating it back to the IT load. From there, comparing this heat removed with the energy required to remove it allows users to see which of their units are efficient and which are not, enabling them to tackle their PUE numbers from the source,” said Bob Hunter, Trendpoint Systems CEO.
The benefits of Micro PUE, according to Trendpoint, include not only pinpointing specific causes of energy inefficiencies, but reducing overall PUE through a link to cooling energy – a white paper example shows that a 10% reduction in cooling energy usage effectively led to 4% improvement in overall PUE.
Experts though feel that while Micro PUE may have good intentions, it may take time to stand on its own as a metric.
“This isn’t a high priority for the average enterprise data center manager. But colocation facilities that are closely tracking cooling costs may be the first to see a benefit in this metric,” said Julian Kudritzki, VP of Uptime Institute Professional Services.
Julius Neudorfer, CTO of North American Access Technologies, Inc., feels that the metric may be just a creative marketing ploy.
“Inventing the term ‘Micro PUE’ seems to me to be an extreme case of riding the PUE bandwagon a little too far,” said Neudorfer. “Cooling system performance already has several well-defined efficiency metrics — Coefficient of Performance (COP or CP) and Energy Efficiency Ratio (EER). These existing efficiency metrics express the performance ratio of the amount of energy required to remove a given amount of heat.”
“The article concentrates on CRACs and CRAHs, which are generally the most difficult to alter for improved efficiency,” said data center design expert Robert McFarlane of Shem Milsom and Wilke. “Modern, high-efficiency data centers require ‘source of heat’ cooling. This is much more physically flexible than CRACs or CRAHs, so it can be realistically relocated to improve cooling efficiency and PUE, and can be added to existing data centers to either supplement or replace less efficient CRAC or CRAH units. While Micro PUE could well highlight cooling inefficiencies, its use with more closely coupled devices could be much more effective in actually enabling problems to be addressed.”
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