Data Centers (Heart) Energy Efficiency

Brian Wood Blog

Continuing with the current theme of energy efficiency and data centers, we’ve looked at ways that data centers are slowly improving. But what prompted them to improve? Was it the need to keep up with the world’s trend of focusing on energy consumption and conserving it? Was it the need to save money? Whatever the reason, data centers are working on getting better.

As recently as last year, in a survey of 1,100 data centers, the Uptime Institute reported average power usage effectiveness (PUE) of 1.8 to 1.89. That was a definite improvement over a 2007 survey which found the average PUE to be 2.5. In 2009, the Environmental Protection Agency (EPA) reportedly put the average U.S. PUE at 1.91. As a whole, numbers are dropping and that’s a good thing.

PUE is basically a measure of overall data center efficiency and lower scores are better. Ideally, PUE scores of around 1.0 are considered good, while scores of 2 and over 2 are less desirable. While there is no standardized way of measuring or calculating energy efficiency, PUE is about as good as it gets for now.

PUE looks at the total energy supplied to a data center and then divides that amount by the amount of energy that actually reaches the IT equipment. It reveals/exposes how much energy is expended on cooling systems and other non-compute functions. A PUE of 2.0, for instance, means that for every 2 watts supplied to the data center, only 1 watt reaches the computing equipment (

Data Centers Heart The Earth 1

Average Data Center Power Allocation (

Poor PUE scores can be attributed to older designs and equipment, under-utilized assets, wasted space, and other design and operating issues.

Online giants Google and Microsoft claim to have PUEs closer to 1.0. These large firms are special cases as many of the data enters they operate are newer and they invest heavily in IT efficiency. IT efficiency affects much of their operating costs, so it makes a lot of sense.

A Digital Realty Trust survey from last year suggests there have been increased efforts to decrease energy consumption and improve efficiency. Four out of five respondents (80%) said that they took steps to keep hot exhaust air from servers mixing with cold air used for cooling, known as “hot-aisle” or “cold-aisle” containment, a number that is up considerably from the year before. 85% of respondents also claim to use some sort of data center infrastructure management software, an emerging class of products that can be used to improve energy efficiency (

Of course there are still data centers that are less energy efficient as others. However, they will get better simply because they have to; global pressure to “go green” is as strong as ever. Beyond that, it just makes sense and is smart business. The basic goal of any organization is to get the most out of as little as possible. If that means they can do their part by positively affect the environment while saving money in the process, even better.

Data Centers Heart The Earth 2

Going “green” at a data center (