A Spanish city council implemented power management software on 3000 computers to automatically put computers into low-power sleep states during periods of inactivity. The software tracked computer power states and user activity every second. It found that after implementing the software, computers spent more time in low-power sleep states, saving an estimated 53.9 kWh per computer per year. This was within 1.1% of projections, meeting the customer's goal of less than 20% deviation from projected savings.