Leaving the wi-fi router on when you go out to work for the day might seem an innocuous and harmless thing to do.

But now researchers from the University of Essex have warned that certain devices around the home are sapping up energy - costing people money on their electricity bills.

Appliances such as wi-fi routers and televisions are known as "energy vampires" due to the fact they consume electricity even when not in use.

Many people have been given personalised advice on how much those devices are costing them.

But the university's research shows that despite the incontrovertible figures, which show energy vampires account for as much as 10% of someone's bill, people are still not switching the items off at the mains in order to save cash.

Dr Kathryn Buchanan, from the University of Essex's department of psychology, said: "In a YouGov survey energy bills emerged as a number one concern for UK citizens, over and above other household bills, including petrol, food and mortgage costs.

"You would therefore assume that if they were given an option to save money on their energy bills, they would jump at the chance.

"But surprisingly we found that although giving feedback to residents increased their knowledge about their energy consumption, it didn't persuade them to change their habits to reduce their bills."

The findings could mean energy firms and environmental groups need to find new ways of persuading people to reduce their energy consumption for the benefit of the environment.

However it is hoped the rollout of smart meters will present new opportunities for providing customers with information to help them use less.

Dr Buchanan and Professor Riccardo Russo, also from the department of psychology, tested different feedback options, from providing people with generalised information about what the average household could save, through detailed personalised breakdowns of the costs associated with individual appliances in their own homes.

They tested whether people responded better if they were told they were wasting money, rather than saving it and if combining feedback with practical advice on what people could do to cut costs made any difference.

Finally they tested whether guilt-tripping people by telling them they were using more energy than average, or that everyone has a shared responsibility for reducing energy use, had any effect.