PUE data centre efficiency metric to be standardised ‘within months’

The Power Usage Effectiveness (PUE) metric, which measures how efficiently a data centre uses its power, is set to become an ISO standard within the next year, according to The Green Grid.

Speaking at The Green Grid EMEA Forum in Brussels, Andr Rouyer, Industry and Government Alliances at Schneider Electric and EMEA Liaison Work Group Chair for The Green Grid, said that standardisation is key to the future success of the metric.

“It takes time to do this, there is a process to follow. But PUE will be standardised in a few months,” he said.

PUE compares the total energy consumed by a data centre to the amount of energy that actually reaches the IT equipment, showing how much is lost to other equipment such as cooling systems.

While PUE has won support within the IT industry, there has not been a standard way to measure it, meaning that operators can fiddle the figures in their favour if they choose to do so.

This makes it difficult to compare the energy efficiency of one data centre to another, and also means that the metric cannot be used as a point of reference in any official or legal situation.

Efforts to define a common way of measuring and publishing values for PUE, and get it recognised as a formal standard, have been carried out by a taskforce of global leaders from government, industry and the non-profit sector since 2009.

The taskforce includes The Green Grid, the US Department of Energy, the Environmental Protection Agency’s Energy Star Program, the Uptime Institute and the US Building Council, among others.

The most recent version of the taskforce’s recommendations was published in May 2011 and is available here, and the first plenary session with the ISO (International Standards Organisation) took place last November.

Now it seems that the efforts of the task force have finally paid off. Once PUE becomes a standard, data centre operators will have to follow a very strict set of rules on how energy consumption is measured. This should, in theory, make data centre PUE ratings stand up to scrutiny.

Rouyer warned that standardisation is not the same as certification. Once the standard is in place, it will be up to an external body like KPMG to set up a certification scheme, whereby data centres are audited and PUE ratings verified. However, standardisation is an important first step.

“In future, rather than referring to our metrics, we can measure PUE according to the ISO standard,” said Paolo Bertoldi, Directorate-General of the European Commission’s Joint Research Center (JRC).

The news could have significant implications in the UK, where the government’s CRC Energy Efficiency Scheme forces large organisations to monitor their emissions and purchase allowances for each tonne of CO2 produced by the energy they use.

Intellect, the UK tech industry’s trade association, has been campaigning on behalf of the data centre industry for the government to grant the sector a exemption from the CRC, due to the contribution that it makes to reducing power consumption in other industries.

The data centre industry hopes to secure a Climate Change Agreement (CCA) that acts as a carrot rather than a stick, offering a £22 rebate for every tonne of carbon saved. However, in order to secure a CCA, the industry needs to provide evidence of the energy intensity of data centre operations.