Christmas gift gadgets could add up to an extra £150 on energy bills unless families change their habits, researchers have warned.
And the £25 a year saved by bringing home loft insulation up to the recommended 270mm thickness could be lost with just a couple of presents, according to academics at the University of Salford.
The warning comes after researchers looked at some of the most popular gifts and worked out how much they would cost to run if the family left gadgets on standby or permanently charging up.
Leaving electrical items on after the battery is charged costs around £3 per gadget per year, a TV and set-top box which are on for six hours a day and on standby all the time would add £30 to household electricity bills, while a Blu-Ray player would average about £7.
Six hours a day of gaming with the console on all the time would cost about £50 a year.
Erik Bichard, professor of sustainable development at the university's school of the built environment, said: "We don't want to look like Scrooges at Christmas, but people tend to forget that these gifts can be a real drain on their energy use and their family finances.
"For example, a laptop only takes a couple of hours to recharge, so if you leave it on charge all the time you are using far more power than it needs. If you use a laptop for work and at home, so that it is active for say 25% of the time but plugged in all the time, it will cost around £13 a year.
"A laser printer on standby would add £17 on standby and another £20 if used for an hour a day while a modem adds £9."
Researchers at the university have built an 'Energy House', a typical Coronation Street-style terraced house, furnished and fitted as an average working home with fully functioning water, gas and electricity supplies.
It is also a sealed testing chamber so that energy use can be monitored to find out how the estimated 4.5 million pre-1920s terraced houses in the UK can become more energy efficient.