Power Usage Effectiveness (PUE) to Make Data Centers Efficient

A data center needs constant uninterrupted power supply to run smoothly. Power is required to keep the servers operational, provide cooling for the servers and also for lighting the facility. The efficiency of a data center is determined by the overhead energy consumption (cooling, power loss, lighting etc). Lower the overhead energy required to run the data center, the higher the efficiency. Looking at logistics, a conventional data center runs at an average of 100% overhead which is highly uneconomical.

To reduce unnecessary power consumption by data centers, Green Grid, a non profit organisation working towards improving the efficiency of data centers developed the Power Usage Effectiveness metric or PUE to measure the effectiveness of the data center.

What is Power usage Effectiveness (PUE)?

By definition, Power usage effectiveness (PUE) is a measure of how effectively a data center uses its power; specifically, how much of it is used by the computing equipments in contrast with overheads. In other words, PUE tells you how much extra energy is needed for each usable KWh for the IT equipment due to the power going into overheads like cooling, lighting, power distribution loss etc.

Why is it required?

It is important to know that running a data center alone is not enough; in today’s green obsessed world, one needs to find ways to run and maintain an energy-efficient data center. Equipments in the data center have to be constantly monitored to ensure they don’t draw unnecessary amount of power to sustain. If the data center is not fine-tuned every now and then to keep them running efficiently, you will have to shell out exorbitant amounts of money just to keep up with the power demands of the data center.PUE was created  keeping only one thing in mind- to run the data centers efficiently .

How is it measured?

In theory, it’s a very simple formula,

PUE = Total Facility Power/IT Equipment Power

The above formulae measures how much overhead energy is required to house and cool the computers inside a building relative to the amount the computers consume themselves

PUE is hence, expressed as a ratio where you will find out if your data center is energy efficient. You can find that out when/if the quotient decreases towards 1. Just remember, the lower your PUE, the more efficient is your data center infrastructure.

How to collect data to determine PUE?

• Take down the readings of the energy use of the data center from the center’s utility meter.
• Measure the various IT equipment load after power conversion, switching and conditioning is over. This measurement should represent the total power delivered to the server racks in the data center.

Ideally, the PUE reading of an average data center reads 2.5. This ratio can be further decreased to just 1.6PUE by using efficient equipment and adopting green practices.

How can you bring the PUE down?

There are simple steps which can bring down your power consumption levels by 65%!

• Space optimization– Other than the IT equipments, the main power consuming system is the cooling structure. Stacking the servers in racks and providing overhead cabling to prevent clutter under the raised floors optimises cooling .This, in turn, promotes an ideal environment and reduces power wastage.
• Incorporating alternate energy– Depending upon the location, the data center can use energy sources like solar, wind, hydro, etc to run their data centers on a partial basis at least.
• Upgrading the IT equipments– Upgrading old equipments not only improves the power consumption rate but also ensures the smooth running of the data center.

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