The scheme, in partnership with Evolve Energy, focused on installing energy monitoring and control systems for existing lighting, heating, ventilation and air-conditioning systems in 260 of the group's larger food stores.
Stores are monitored 24 hours a day to ensure that savings are being sustained, and an internal alarm system is able to diagnose faults before they lead to any unnecessary energy wastage.
Engineers are also able to fix many problems remotely, meaning that callout costs are significantly reduced, and equipment lasts longer.
Alex Pitman, group energy efficiency manager for the Co-operative Group, said he was thrilled with the results so far.
"These measures are both environmentally and financially viable, and we now have the ability to constantly manage our energy usage," he said.
He hopes to see the system rolled out across the group's estate, helping it achieve its target of cutting energy usage by 25% by 2012.