The following opinion is presented by David Palmer-Stevens, SI Manager for EMEA at Panduit, a manufacturer of physical infrastructure solutions that support power, communications, computing, control and security systems. 

At the end of last year, The Green Grid announced that the Power Usage Effectiveness (PUE) metric, which measures how efficiently a data centre uses its power, was set to become an ISO standard within the next year. PUE, which works by comparing the total energy consumed by a data centre to the amount of energy that actually reaches the IT equipment, is designed to highlight areas where energy is being wasted.

The crux of the argument

Whilst PUE has won the support of many in the IT industry, I would argue that it’s simply an inefficient metric that can be easily manipulated by data centre managers.

The problem is that PUE is a meaningless measure; it is simply a bad number that is completely exposed to manipulation. Even for data centre managers who are doing the right things to make the data centre operate more efficiently, the PUE number may not even change to reflect those adjustments.

For example, if an organisation swaps out all of its old servers for new Intel based servers they will be getting the same CPU power but for half of the consumed power. This is halving the Server power requirement for the same applications, therefore halving the cooling cost, yet the PUE number will not change.

Setting a meaningful standard

Since 2009, there has been a real effort from government, industry and non-profit sectors to define a common way of measuring PUE, and of course we can all agree that there do need to be standards and guidelines in place to ensure that datacentres are operating efficiently.

The fact is, if we are going to have a standardised data centre efficiency measure, it has to actually reflect the true power efficiency of the data centre, otherwise, as we are seeing with PUE, it renders the metric completely pointless.

As it stands, all datacentres are built to international standards such as ANSI/TIA 942, and follow best practice from organisations such as ASHREA and The UPTime Institute so that they are operating within certain thermal limitations. But, in order to get the green agenda into data centre operations, we need to ensure that green measures are a mandatory part of the standards process… and then the rest will follow.

The key is compliance

The key will be to make some items compulsory for compliance. First, ensure that there is a mandatory equipment refresh cycle. Last year, a Forrester report estimated that in Europe 84% of data centres were more than 14 years old, which means that, in some cases, equipment has not been upgraded for over a decade. Discarding old and unused equipment will not only save on maintenance costs, but also on power and cooling. If datacentre managers invest in new equipment, they will see a significant impact on their energy bills, as not only are new servers more power efficient, but this year’s Switches supporting IEEE802.3az are estimated to save up to 70% of Switch power.

The next step would be to make hot aisle and cold aisle containment compulsory. The datacentre is fraught with power and cooling challenges, but one of the biggest problems is that for every piece of equipment, not only is power needed to keep it running, but even more power is used just to cool it. This means that a huge amount of cooling energy is wasted, and containment is the best way of addressing this. The question of containment is no longer whether you should be doing it; the question is how much should you be doing.

If the green committees really want to get the green agenda embedded into the data centre construction and management process, they need to work more closely data centre managers. Educating organisations on the ROI they can get from taking simple steps such as refreshing equipment, would give companies more of an incentive to actually be green, rather than just allowing them to manipulate the numbers so they can tick a box.