A study by the price comparison site found an estimated 17 million homes in the UK (nearly two thirds of households) set their thermostat above 20°C. Turning down the dial by just one degree could save up to £80 a year on energy bills.

It means the 17.7 million households setting thermostats above 20°C could save a total  of £1.4bn, if they all turned the temperature down a degree.

The average temperature in a UK home is 20°C — a full degree higher than climate change experts recommend.

A tenth of UK households heat their home to 25°C or above, with young people aged 18 to 24 the most likely to turn their thermostat up this high. Only 3% of those aged 55 or over had the central heating set at this temperature – which is hotter than Tenerife.

Six in 10 (60%) of over 55s said they set their thermostat to 20°C or above. Age UK recommends older people keep the rooms they use most at 21°C.

Sarah Broomfield, energy expert at Uswitch.com, said: “With temperatures falling, many of us have already turned our heating on, but it’s amazing to think that an estimated two million homes are currently hotter than Tenerife.

“While it is important to stay warm over the winter, and older people especially should keep their heating on to look after their health, higher temperatures are one of the biggest contributors to higher energy bills and carbon emissions.

“Anyone who is worried about paying their energy bills this winter should contact their energy supplier, who can offer advice and support. Some people may be eligible for free insulation grants to help them pay for home improvements that will keep costs down longer term.

“Switching tariffs or changing your energy supplier is another way to make significant savings, so now is a good time to run an online comparison to see what energy deals you could be getting.” If your heating system is more than a decade old or is breaking down frequently, it may be time to invest in a new, more energy-efficient heating system installation.