Energy-related costs account for around 12% of overall data centre expenditure, but firms are continuing to struggle to cap this spending, according to analyst Gartner.

Gartner said energy costs are the fastest rising cost in the data centre. It says that power and cooling cost problems are likely to worsen during the next few years, as organisations grow their technology infrastructure as they emerge from a recessionary period.

"With upwards of 5% growth for server shipments predicted per year over the next two years, organisations need to forcefully control their energy consumption and costs," said Gartner analyst Rakesh Kumar.

"To do this, he said, data centre operators need to measure energy-related data across the whole site, including the building, the facility's components and the IT equipment portfolio."

Gartner analysts said continuous power utilisation efficiency (PUE) readings to help control costs will become the norm for most large data centres, and that by 2015, 80% of new large datacentre s will report continuous PUE readings across the data centre .

"However, despite the wide availability of measurement tools, experts and consultants, datacentre operators struggle with the best place to measure the energy in their data centres," said Kumar.

"What is needed is a breakdown of the ideal approach to data centre energy management into a pragmatic approach that will provide sufficient information for most operational planning purposes."

To get a comprehensive, accurate and real-time record of the energy used in data centres, Gartner recommends that users need to measure across six areas: building, electrical facilities, building facilities, racks, IT hardware and virtual machines (VMs).

By measuring across these areas, data centre operators can obtain a "highly detailed, comprehensive and real-time usage picture" of the energy that is being consumed across the whole site, said the analyst.

Industry groups and government agencies from Europe, the US and Japan recently reached a basic agreement on how to measure the energy efficiency of data centres.

Key issues facing the data centre industry will be covered at the Gartner Datacentre & IT Operations Summit 2010 in London on 22-23 November.