So-called green IT is getting increasing attention, not only from vendors claiming to offer more environmentally-friendly products, but also from firms that are taking energy efficiency and carbon emissions seriously as a business issue.

There are numerous schemes by which companies can claim to be doing their bit for the environment. One is carbon offsetting, whereby a certain number of trees or other biomass is established to absorb an equivalent amount of carbon dioxide emitted by manufacturing computers and generating the electricity to run them.

But according to many experts, such offset schemes can be a minefield, as the carbon offset industry is largely unregulated and schemes to plant trees in developing countries can be poorly managed. Much of the science behind this approach is uncertain, with calculations of the amount of carbon dioxide taken up by new plant growth varying wildly.

As critics of such schemes have pointed out, paying to plant a few trees is just a way for polluters to salve their conscience while continuing with business as usual. It must surely be a better idea to ensure your carbon footprint is reduced in the first place.

For most of us, that means trying to use less energy, especially in the current climate of soaring electricity prices. IT infrastructure is sadly a great contributor to global demand for electricity. So what can firms do? Investing in kit that consumes less energy is one way of tackling the problem, as is ensuring computers are not left running when not in use.

The major PC builders have already started to meet the challenge by introducing more power-efficient systems, such as HP’s dc7800 desktop that IT Week reviewed last year. However, while these may save businesses some money on energy bills, the benefit is likely to be small compared with the cost of replacing existing systems, and so power-saving PCs will only start to appear as part of the normal corporate refresh cycle.

Ensuring computers are not wasting energy unnecessarily is another step firms can take. Tools such as Verdiem’s Surveyor software enable administrators to monitor energy usage and set policies to put PCs into power-saving states whenever possible.

But as IT Week has found, a PC’s power supply and associated circuitry can still consume a surprising amount of energy, even when it is switched off. Using a power meter, we found some systems consume 20W all the time they are connected to the mains power, even without being turned on.

Clearly, much work has still to be done to improve the power efficiency of computers, and so it looks like being a long road before IT can genuinely be called green - ­ and I have not even touched on the subject of server farms.