PUE Category 3 is Within Reach for all Data Centers
Posted on Tue, Jul 20, 2010 @ 03:31 PM
Power Usage Effectiveness (PUE), a metric for measuring efficiency in the data center, has become the “hot” data center topic of 2010. Not all of the attention has been positive. At its core, calculating PUE is dead simple. You divide the amount of power entering a data center by the amount of power used to run the computer infrastructure within it. However, the details on how to accurately calculate PUE were vague – until now. This resulted in a wide variety of techniques and results that made it difficult to compare separate data centers based on the metric.
On June 15, a task force comprised of “who’s who in data center efficiency,” a list that includes ASHRAE, The Uptime Institute, and others released the new “Recommendations for Measuring and Reporting Overall Data Center Efficiency”. The authors acknowledge that data centers have varying degrees of sophistication when it comes to ability to measure PUE. In the core three tenants listed at the beginning of the document, they state:
“When calculating PUE, IT energy consumption should, at a minimum, be measured at the output of the uninterruptible power supply (UPS). However, the industry should progressively improve measurement capabilities over time so that measurement of IT energy consumption directly at the IT load (i.e., servers) becomes the common practice.”
The report goes on to establish four levels of PUE with “the intent to encourage operators with limited measurement equipment to participate” with PUE Category 0 being the least accurate and PUE Category 3 having the highest degree of granularity and accuracy. The requirements for PUE Category 3 according to the report are listed below.
PUE Category 3
This is a consumption-based calculation. The IT load is represented by a 12-month total kWh reading taken at the point of connection of the IT devices to the electrical system. This is a cumulative measurement and requires the use of kWh consumption meters at all measurement points. Total energy is determined in the same way as Category 1. This measurement method provides the highest level of accuracy for measurement of the IT load reading by removing all impact of losses associated with electrical distribution components and non-IT related devices, e.g., rack mounted fans, etc.
At Viridity Software, we believe the cost and effort involved in “measurement equipment” should not be a barrier to data centers seeking to achieve PUE Category 3 level of measurement. We believe that all data centers should be able to measure energy consumption at the server level without having to spend hundreds of thousands of dollars on hardware, and months of man hours on training and deployment. Viridity EnergyCenter software is up and running in minutes, and starts returning actionable data about power consumption at the server level within hours. Learn more about Viridity’s EnergyCenter.
Michael Tresh
Director of Product Management
Viridity Software