Martin Lewis has issued an urgent warning over a simple mistake which could add hundreds to your energy bills.

The MoneySavingExpert.com (MSE) website founder shared the advice on his ITV show - the Martin Lewis Money Show - earlier this week. During the show, Martin spoke to members of the audience about their energy dilemmas and in this week's show.

One audience member told the financial guru that they turned their thermostat up by one degree in the winter months but Martin questioned them on why they were doing this warning that it was "unnecessary" and "costly".

Martin said: "A thermostat says: 'we will keep it at a set temperature'. Why are you turning it up in winter? That's what the thermostat does. If you want it to be 20 degrees it will stay at 20 degrees and that's the right temperature for you. You don't turn your thermostats up in winter, you just let it get to the heat. That's all you need to do."

Martin has shared this money-saving energy tip before alongside many others on his ITV Money Show. Another piece of energy advice shared by the MSE founder on a previous episode was for those who had a combi-boiler.

What are your tips for lowering your energy bills this winter? and do they work? Let us know: mirror.money.saving@mirror.co.uk

Martin said households should be checking what the flow temperature of their boiler is. This is the temperature your boiler heats up the water to before sending it off to your radiators. On a previous episode of his show, Matin explained how your boiler's flow temperature should be set at 60 degrees - but most are automatically programmed a lot higher than this.

If your boiler temperature is set higher, then it is "really inefficient" for your boiler.

He explained: "You normally want it to be around 60° but most people's boilers are set higher - that’s really inefficient. You can turn this down, it won’t affect the heat in your house, and it’ll still be the same temperature. It won’t affect your hot water temperature - it might take slightly longer to get up to the maximum temperature. But it can cut £100 a year off your bill and is well worth everyone doing. This is an absolute no-brainer and everyone with a combi boiler should be trying this.”

If you’re unsure how to lower your boiler flow rate, Martin recommended using the free MoneySavingBoilerChallenge.com website.