Does wearing a jumper save money on energy bills… and how much?

As the UK goes through another cold snap, households are desperately looking for ways to cut back on their record heating costs.

When we reach for the thermostat dial, most of us will still hear the age-old money-saving advice of ‘Just put another layer on!’ echoing in our ears. 

But how much can the humble jumper actually save you?

This Is Money has worked out how much you could save by putting on a jumper rather than reaching for the thermostat dial.

A thick wool jumper makes you feel 4C warmer, according to This is Money’s experiment

Based on our experiment, the average household could save £250 a year, rising to £300 when the Government’s energy price guarantee is readjusted in April. 

To work this out, we have set a few parameters. First, we assume that someone feels warm at a room temperature of around 18C, and starts feeling cold slightly below that level.

Of course, we all start feeling warm or cold at different temperatures, and live in properties with varying degrees of insulation. 

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But 18C is the recommended winter room temperature by the World Health Organisation, while the Energy Saving Trust suggests rooms should ideally be 18C to 21C.

During cold weather, Government advice has been to heat rooms to at least 18C for health reasons, especially for the sake of elderly residents. 

This is because cold weather can increase the risk of heart attacks, strokes and chest infections.

Putting on a jumper before putting your central heating temperature up can save you £250 a year on energy costs

Most Britons seem to prefer being slightly on the warmer side of the 18C to 21C range, however. A study by Uswitch previously found an estimated 17million homes in the UK set their thermostat above 20C – that’s around 70 per cent of all households.

To work out how much wearing a jumper saves you, we also assume that everyone in the property is willing and able to wear more layers and accept overall room temperatures being slightly colder.

How much money wearing a jumper really saves you 

If you sit in a 15C room wearing a t-shirt, the average person is likely to feel cold after a short while.

But if you add a light wool jumper, this traps extra warm air near your skin, helping you feel warmer.

To find out how much warmth is generated we used a thermometer, and found a light jumper increased your temperature by 2C. 

This means the room now feels like 17C, getting close to the target temperature of 18C.

However, wearing the same t-shirt with a thicker wool jumper on top added 4C to the wearer’s temperature and left them feeling very warm indeed. 

Wearing either of the jumpers above should mean the wearer could afford to turn down their central heating slightly to compensate for feeling warmer.

Turning your thermostat down by just 1C will knock around 10 per cent from your yearly energy bills, according to the Energy Saving Trust charity.

Energy bills for the typical household with average energy usage are capped at £2,500 a year due to the Government’s Energy Price Guarantee, which was unveiled last year to help with soaring costs. 

That lasts until the end of March this year, when it rises to £3,000 until April 2024.

Ten per cent of £2,500 adds up to a saving of £250 a year for just a 1C reduction in your thermostat temperature, rising to £300 a year from April 2023. 

However, turning your thermostat down by 2C does not mean a £500-a-year saving, because the rule only works once – and after that the savings are smaller and harder to work out.

As mentioned already, there are also huge variables that affect how much layering up can save you on energy bills.