A report by analyst firm Forrester has concluded that IT managers must manage PCs differently if they are to cut power usage and hit green targets.

According to thinktank The Climate Group, PCs account for three times as much power consumption and carbon generation as datacentres, and very little attention has been paid to how to use computers more efficiently.

“Enterprise PCs are wasting money,” said Doug Washburn, author of the Forrester report "How Much Money Are Your Idle PCs Wasting?"

“Far too many organisations leave economic and environmental value on the table by not reducing PC-related energy costs. Unfortunately, common misconceptions – like alleged power surges when turning on PCs or the presumed energy-saving benefits of screen savers - can inhibit organisations from taking action or even lead to more energy-inefficient behaviours,” Washburn added.

He highlighted measures that could be used to improve the efficiency of PCs and deliver concrete benefits.

For example, powering down PCs at night and over the weekend can save a company between $25 and $75 per PC over a year. Washington Mutual, General Electric and Dell claim savings of $3m per year, $2.5m per year and $1.8m per year, respectively, by doing this.

He also recommended the use of PC power management software, which can power up or down the PC at set times or if it is not being used.

Washburn also highlighted some myths about PC power management. Some administrators still think leaving a computer on lengthens its lifespan, as cooling and heating up of components by switching it off makes them more prone to failure, he noted.

While this was true in the very early days of PCs it is no longer the case and indeed the reverse may be true, Washburn said. Leaving the computer on keeps the fan going and draws more dust into the machine.

Screensavers are also not an effective technique of power saving. A graphics-heavy screensaver can instead increase the amount of power the computer uses.