Its researchers, acting as mystery shoppers, discovered they could find a cheaper deal in 62 per cent of the cases they investigated.
John Dalli, the EU's commissioner in charge of health and consumer policy, said: "Potential will only be fully realised if consumers know that they could be getting better deals and feel it is easy for them to find those."
One method of sourcing such tariffs is by comparing electricity prices via a site such as UK Power.
Other ways to reduce home energy bills include adding a smart meter, with recent research by Datamonitor suggesting this is a trend that will grow by 350 per cent between 2009 and 2015.
Posted by Jim Tidy
Click here to run an energy price comparison, and see if you could be paying less for your gas and electricity.