PUE: a marmite issue?


Louise Frampton, Editor, Mission Critical Power magazine, discusses the value of PUE as a tool for improvement.

The Green Grid is calling on data centre operators to re-evaluate their sustainability practices by reviewing how they can make their sites more energy efficient, while considering renewable power.

Getting the basics right is a good place to start and simple changes can make a difference, but is PUE still relevant to driving forward this agenda?

PUE has gone as far as it can but energy usage and power generation will become the focus for innovation in data centres, according to Phil Collerton, managing director of the Uptime Institute in Europe, Middle East and Africa.

Uptime Institute recently launched an ‘efficient IT programme’, to provide a holistic approach to eliminating waste and reducing resource consumption. For adopters of efficient IT, Uptime Institute’s experts have identified cost savings between 3x-200x the cost of the assessment. Collerton points out that IT teams are “rarely on the hook” for the actual energy costs within an organisation. He acknowledges that PUE has been an important initiative, driven by the Green Grid, which has changed the way people upgrade data centres. People are much more aware of how they run their units to save energy, but it will be difficult for data centres to lower their PUE any further.

LinkedIn was recently awarded the Efficient IT (EIT) Stamp of Approval for LinkedIn’s data centre in Infomart Portland. The Efficient IT Stamp of Approval by Uptime Institute is a complete evaluation of enterprise leadership, operations, and computing infrastructure designed to help organisations lower costs and increase efficiency, and leverage technology for good stewardship of corporate and environmental resources. This award for Efficient IT certifies an organisation’s sustainable leadership in IT, evidencing better control of how resources are both consumed and allocated.

LinkedIn’s Portland data centre is powered with low-carbon power sourced from the Bonneville Power Administration, one of the largest suppliers of hydroelectric power in the US. To further optimise efficiency, in order to meet a dynamic and energy dense load profile, LinkedIn chose an innovative cooling design element that adjusts to the variable heat load. The Portland data centre also features advanced monitoring for maximised environmental control.

While LinkedIn provides a model of efficiency that others can aspire to achieve, there is still a great that can be achieved on significantly more constrained budgets, by making simple changes.

Simon Brady, head of data centre optimisation at Vertiv, recently discussed the optimisation of legacy data centres and commented that there is “no such thing as the perfect data centre”; there are common problems that many data centres share, yet there is a shroud of secrecy around these issues. He described PUE as a ‘marmite issue’ – you either love it or hate it. During a live webcast, he commented that it can be divisive; it should not be used as a ‘my data centre is better than your data centre’ tool, but as an internal benchmark – a value to improve upon, he argued. He believes it is still relevant if used correctly and as part of a robust optimisation plan; a view shared by the majority that took part in the online survey.

Even simple, low interventions can deliver significant efficiencies: one data centre went from a PUE of 2.17 to a PUE of 1.67, delivering a saving of 1,454,603 kWh/year, by making small changes. In the world of ‘data centres anonymous’, there are common issues that can be found in most facilities, such as gaps in the floor. Individually, these may seem insignificant, but at one data centre these gaps were found to add up to a 18m2 hole. Tackling these problems costs very little, but saves a great deal.

Ultimately, PUE is still widely recognised as a relevant benchmark for today’s data centre. As the saying goes, “If you can’t measure it, you can’t improve it,” but how it is used is the crux of the matter.


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