Tracking PUE Can Help Create More Efficient Data Centers

This is Casey Laughman, managing editor of Building Operating Management magazine. Today's tip is that power usage effectiveness, or PUE, can be a good metric for measuring data center efficiency.

Calculated by dividing total site load by IT load in kilowatts (kW), PUE is a good gauge of a facility's energy efficiency, but relying on it alone can be misleading. For example, a new data center designed and equipped for energy efficiency and future expansion which is not yet operating at full design load initially will have a poor PUE. PUE will also degrade if an owner installs new servers with more energy efficient power supplies in an existing data center.

But, as an overall snapshot of how efficient your data center is, PUE is effective. The goal of the "PUE Arms Race" is to drive down power usage effectiveness to 1.0, where the only energy used is the energy powering the computer.

There are three fundamental ways to improve the energy efficiency of a data center. One way is to install new computer equipment with more efficient power supplies, and this is often done as owners periodically refresh their computing equipment. Another is to implement on-site power generation, for example, cogeneration or solar power. These grand-scheme approaches are not often implemented today, but they have increasing potential as the technologies improve and their capital cost decreases.

The third approach is to design, engineer and operate data centers to maximize the efficiency of the building infrastructure. Whatever else an organization is doing, this is fundamental to improving energy efficiency. Here is a look at some of the leading trends in mechanical and electrical systems. Many of the techniques being implemented by data center owners and engineers have an established track record in non-critical facilities. With data center energy costs escalating, these techniques are making their way into the mission-critical arena.

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