It's encouraging that many of the conversations we are having at the moment in relation to IT and sustainability are moving beyond power management in the data centre. It is not that optimising the use of central IT isn't important, but it really is only one way to drive an organisation's environmental agenda. And even before we get to the main question of how technology can enable more eco-friendly working practices, there is another place we can look to for operational IT power savings—the desktop.

When looking in this direction, though, I have noticed that there is a tendency to apply the same kind of thinking that is used on the server side of the equation. Fair enough, accelerating hardware refresh to introduce more power efficient kit into the equation reflects a similar game to that being played in the data centre, but with the carbon cost of manufacture/disposal taken into account, the net gains are hard to establish. In the data centre of course, hardware modernisation is augmented by consolidation and virtualisation to drive up average server utilisation and thus improve energy efficiency.

Virtualisation is a different game on the desktop, however. Sure, some will go down the route of running virtual PCs on the server and accessing them through thin client configurations, but it will be a long time before this is the norm. The reality is that most organisations will remain wed to their fat clients for the foreseeable future, so we need to think of the energy question a bit differently. Essentially, the challenge boils down to optimising the power consumption of desktop machines that typically idle for the majority of time they are switched on.

In order to deal with this problem, we need to think less about utilisation and inherent power efficiency of hardware and software, and more about controlling the state of machines in terms of their sleep/wake cycle. In practice, a configuration exhibiting a high degree of runtime energy efficiency, but has no active policy to transition to a low power state when idle will consume considerably more power than a less efficient machine whose state is properly managed.

This is something that Microsoft makes a big point of when talking about Vista in the green context, and indeed early adopters with large Vista estates corroborate Microsoft's claims that Vista's enhanced manageability translates directly to power savings. The problem is, however, that Windows XP isn't going away in a hurry, so what about all of those organisations who are interested in desktop power management but will be maintaining older versions of the operating system for some time to come?

Well the one approach that is generally acknowledged not to work that well is to educate, encourage or threaten users in an attempt to get them to keep their power configuration set in accordance with environmental policy, and/or to manually shut down their PCs or put them to sleep when they are not in use. IT managers relying on this kind of user discipline are probably not going to see the results they were hoping for unless they're working for a totally green-tinted organisation.

Fortunately, third party solutions exist that can help to enable/enforce centralised power management—a couple of examples being Verdiem and 1E. Using such technology, you can not only cure PC insomnia from a policy enforcement perspective, but also allow real-time remote control of power state so machines can be woken up for backup or software distribution purposes then put to sleep again afterwards. So, if you are serious about saving energy across a large XP estate, the options are there.

Something I haven't had time to look into is whether similar solutions exist for alternative desktops—namely Mac OS X and Linux. Apple kit is certainly not renowned for its enterprise management friendliness, but perhaps 'right on' Mac users aren't so much of a problem as they are of course more environmentally aware. As for Linux, I would be interested in any views, recommendations or experiences.

Meanwhile, it would be great to see a bit more awareness raising from Microsoft on the availability of solutions to centrally manage power consumption by Windows XP, rather than automatically seguéing from this discussion into a Vista upgrade pitch.