Staffordshire County Council has developed software that detects and turns off idle PCs and could cut £40,000 per year off the authority's energy bill.
The software will scan all of the council's 8,000 computers and automatically switch off any left on outside office hours.
Peter Kear, who developed the computer program and is team leader for Staffordshire ICT Desktop Support, said this software differs from other power-saving tools because the PC is actually turned off, and not left in hibernation mode.
The software was written as part of a wider project to improve the council's patch-management processes and should be installed throughout the county by September.
Kear said the machines needed to shut down every day, not just go into hibernation, as part of the patch-installation process. The energy-saving software evolved from this requirement.
An automated email service that informs employees when their machines have had to be switched off by the software has also been developed and should be added to the system soon.
Kear said the council wants to educate people to switch off their machines and not have them rely on the software to do it instead.
By encouraging people to turn off their PCs, they are also more likely to switch off their other hardware, such as monitors, which the current system cannot shut down, he added.
The software runs on a schedule, routinely looking for and turning off any PCs left on between 8pm and 8am on weekdays and throughout weekends. It also produces a series of graphs outlining how many machines are on, how many were switched off and the associated energy savings from turning them off.
Mick Clarke, the county council's cabinet member for organisation and performance, said the authority is Staffordshire's largest user of computers. The "ingenious software" is a simple and effective way of cutting the council's carbon footprint and saving cash, he said.
A recent report found employees who leave their PCs on overnight are costing their companies around £70 per year.