As he took the floor at a recent press briefing, Kevin Fisher, standards and regulations manager for Europe at Intel, had an unusual admission to make to the journalists gathered to hear his presentation on the regulation of energy efficiency within the data centre: he had decided to talk about something else, as there wasn’t enough existing regulation to fill his allotted time.

As Fisher pointed out, the lack of material to work with is in direct contrast to the importance of the subject. Controlling the use of power within the enterprise has become critical – it is just that the law has yet to play a role.

For many, the absence of unwieldy government legislation is welcome. In an effort to mollify any law maker that may be contemplating the introduction of regulation to tax, penalise or cap data centre energy consumption, Intel has joined a European Commission-led project, along with other vendors including AMD, Hewlett-Packard, IBM and Sun Microsystems, to develop a code of conduct for energy-efficiency in data centres.

However, while there is consensus about the desirability of a voluntary code, the nuts and bolts of defining how that code should operate will be non-trivial. Developing an agreed measurement of energy efficiency is an essential forerunner to building any voluntary or incentive-based scheme, says Robin Murray, a manager at the Market Transformation Programme which advises governments on energy efficiency-related policy.

Moreover, it is imperative that any European proposal fits with work undertaken elsewhere, says Christian Belady, a distinguished technologist at HP, such as the US Energy Star programme, which helps purchasers to choose energy-efficient products by looking out for ones that carry its logo, or the Green Grid, a collection of technology vendors looking to agree common energy efficiency standards for technology.

At this stage, though, methods for measuring the energy efficiency of data centres remain surprisingly crude. Belady favours the use of a power utilisation efficiency (PUE) ratio – this allows data centres to be ranked according to how much energy is used by computer equipment compared to the amount consumed by the entire data centre.

Using a PUE measure allows some degree of benchmarking – a target of 2.0 might be seen as a reachable goal, says Belady – but numerous factors can affect what companies might expect from their data centre. For example, a data centre in chillier parts of Denmark will have far greater scope to use free-air cooling from the ambient surroundings than one in sun-baked Southern California.

Nevertheless, some form of benchmarking is needed, insists Belady. Currently, he estimates companies could improve their PUE ratings by as much as 20% by following basic best practice – such as alternating hot and cold aisles within the data centre.

Some improvement in energy efficiency is possible by introducing newer processors, says Intel’s Fisher. But while Intel and rival AMD boast of the increasing performance and lower energy consumption of their new breed of processors, other parts of the data centre, such as power converters and cooling equipment, remain woefully inefficient.

Virtualisation is, arguably, another energy-cutting approach. With servers consuming energy whether they are actively processing or not, virtualisation can push up the usage levels of each machine considerably.

However, while there is widespread support for the thesis that energy efficiency is enhanced through the use of virtualisation technology, to date there is scant data on how much improvement organisations can expect. While hardware makers have long run agreed benchmarks to demonstrate the performance of a single server, measuring the performance of a virtual estate is far more complex – even more so given the lack of involvement from the heavyweight of virtualisation, VMware.

But the process is at least underway. The EC’s Renewable Energy Unit, which is tasked with developing a code of conduct, held its inaugural meeting in early March 2007. Its aim of producing a voluntary system will be widely welcomed. But it is likely to take many more sessions before a consensus about what an energy efficient data centre looks like – let alone how to rate it.