We'll soon be able to measure exactly how much our electric gadgets are costing us. Some 15,000 Britons will receive free energy meters as part of a new government trial aimed at cutting energy use and fighting global warming.

The government hopes that if we can see how much energy our gadgets are wasting when not in use, we'll be spurred into changing our behaviour. And it's often the simple things that are forgotten. A mobile phone charger left plugged in, a big LCD TV left on when no one is watching, or a kettle boiling more water than is needed for a cup of tea.

Going green

"Changing consumer habits is vital if we are to cut our energy use and reduce the impact of climate change," John Hutton, the new business and enterprise secretary, said in a statement.

"Smart meters provide the cutting edge technology to enable this to happen. The results of the trials will provide invaluable evidence to support the future rollout of displays and smart meters; helping to cut consumer bills and cut our carbon emissions."

Some 40,000 UK households will be taking part in the energy saving trials. Some 8,000 homes will be given clip-on, real-time display units for their existing meters, and others ways will be tested to cut energy waste.

Smart meters, on which customers can see on a small screen how much energy each household appliance is using at any time, are seen as a key tool for cutting energy waste.

"Smart meters have great potential to help customers better understand their energy consumption and encourage energy efficiency," Alistair Buchanan, chief executive of energy regulator Ofgem, said in a statement .