Software designed by the University of Liverpool that automatically shuts down computer systems when they're not being used is saving large organisations up to £13,000 in electricity costs each month.

Systems experts at the Uni developed new software called PowerDown, which works by automatically shutting computers down if left unused for half an hour.

Using the University of Liverpool as a test model, the team discovered that 1,600 library-based PCs alone were using 20,000 kW each week unnecessarily – equating to approximately £2,400 in current electricity prices.

Lazy students can't find the off switch

"An average PC, left on for 24 hours a day but used for only 40 hours a week, uses around 17kW of electricity, of which 13kW is wasted," says Lisa Nelson, from the University's Computing Services Department.

"And that figure does not take into consideration other costs such as in air-conditioned buildings, where additional cooling is required to remove the heat created by active computers."

PowerDown is simple to install and staff can chose to opt out if, for example, they are running software on a machine overnight without a user being logged in.

PowerDown has so far recovered 24 million hours of PC inactivity within the University. The software is available, for free, from http://pcwww.liv.ac.uk/powerdown.