All You Need to Know About PUE

If you are in the process of leasing or building a data center, the term PUE will be used often in those conversations. Here is all you need to know about PUE and its impact on data center selection.

PUE stands for Power Usage Effectiveness and is a data center infrastructure efficiency measure that was developed by the Green Grid consortium. It is generally calculated as follows:

PUE = (Total data center energy consumption or power / IT energy consumption or power)

There are four recommended categories for its measurement:

• PUE Category 0: This is a snapshot measurement of the peak utilization/ demand and can be used only for electric datacenters. Datacenters using alternative energy sources cannot use this measurement.
• PUE Category 1: This is a 12 month cumulative measurement and hence more effective than PUE Category 0. It takes into account fluctuating cooling and IT loads.
• PUE Category 2: This category measures the load at the Power Distribution Unit, and hence is more accurate since it removes the losses associated with the transformers and the static switches.
• PUE Category 3: This is the most accurate category reading that eliminates all losses due to non IT and electric distribution equipment.

A recent survey conducted by the Uptime Institute, on how organizations measure PUE, revealed that:

• 29% of organizations surveyed do not measure PUE.
• 15% use Category 0.
• 20% use Category 1.
• 20% use Category 2.
• 10% use Category 3.
• 6% use alternative methods for measuring it.

Whatever be the method of measurement used, it is imperative that today’s data centers strictly follow the policy of monitoring their PUE. Traditional data centers are typically in the range of 1.9 and 2.0, whereas modern data centers such as those of Apple, Google, Microsoft and Facebook have a significantly reduced PUE of up to 1.1.

Alex Carroll

Managing Member at Lifeline Data Centers

Alex, co-owner, is responsible for all real estate, construction and mission critical facilities: hardened buildings, power systems, cooling systems, fire suppression, and environmentals. Alex also manages relationships with the telecommunications providers and has an extensive background in IT infrastructure support, database administration and software design and development. Alex architected Lifeline’s proprietary GRCA system and is hands-on every day in the data center.