Can smartphones help save money on energy bills?
18 January 2014 Last updated at 12:03 GMT
A number of systems allowing customers to control their central heating via their smartphones are now on sale in the UK, promising big savings.
All the systems work by allowing more precise control over when heating is switched on - and in some cases, in which rooms.
But how real are the savings, and who could benefit?
Brian Milligan reports.