Brits are being told to put CRISP packets behind their radiators this autumn - but does it really work?

As winter approaches and temperatures fall, Brits are being advised to try a bizarre new approach to keep homes warm. 

Mark McShane, heating expert at Boiler Cover UK, says homeowners should place empty crisp packets behind their radiators.

Once they've had a quick rinse, the little rectangles of metallised plastic film should be stuck with tape to the wall directly behind the radiator.

According McShane, crisp packet material reflects heat back towards the centre of the room, preventing it from escaping through the walls.

The 'simple yet effective' trick is an 'easy, cost-effective way to make the most of your heating', Mr McShane claims.

It can supposedly save you money on your heating bills while keeping you warm. 

And the more packets you manage to insert behind there, the greater the alleged warning effect. 

But does it really work? 

Professor Ronita Bardhan, a sustainable environments researcher at the University of Cambridge, called the trick 'a creative idea'. 

But it's one that 'highlights how easily scientific principles can be misinterpreted when adapted for household hacks' – and it could be dangerous. 

'The idea of putting crisp packets behind radiators did make me chuckle,' Professor Bardhan told the Daily Mail. 

'There is some scientific logic to the use of reflective materials behind radiators, yet using crisp packets for this purpose is both ineffective and potentially unsafe.' 

Crisp packets are commonly made from layers of polypropylene and aluminium that cannot be separated for household recycling.

That's why crisp packets must be burnt or buried in landfill, where they can take more than 100 years to degrade. 

McShane's idea stems from commercially available radiator reflector panels made of foil, which legitimately reduce heat loss through walls.

'Research shows that this approach can result in modest energy savings, particularly in older or poorly insulated buildings,' Professor Bardhan said. 

However, in crisp packets, the reflective coating is 'extremely thin and intended for light and moisture protection, not thermal performance', so the 'ability to reflect infrared radiation is minimal'.

'In addition, the plastic is combustible and may deform or emit toxic fumes when exposed to sustained heat, making it unsafe for use near radiators,' she added. 

Harjit Singh, a professor of sustainable energy technologies, Brunel University London, also doesn't think there's much point in trying McShane's method. 

'In my view, there is no tangible saving – energy or cost – possible with such a measure,' he told the Daily Mail. 

Crisp packets are not thick enough to decrease the rate at which heat can pass through the wall, Professor Singh said. 

Although the metal in crisp packets can theoretically reflect radiation back to the room, the effect will be 'negligible', he added. 

Another possible way the tactic could backfire is by creating a 'direct thermal bridge' between the wall and the radiator, he said. 

In other words, the heat will be lost to the wall by conduction – the transfer of energy through the direct physical contact – which is the opposite of what we're trying to achieve. 

This is an especially likely if you push too many crisp bags behind the radiator, applying too thick a layer of them.

Ultimately, the best tips to keeping warm indoors are plugging gaps around windows and doors, using excess heat from the oven to circulate, and keeping doors to unused rooms shut. 

Closing curtains can also act as an effective barrier from heat being lost through the windows even if they're closed, according to British Gas. 

'It's also a good idea to set your thermostat to one temperature and then use a timer 'to turn it on and off when you need the heating most,' it says. 

'That way you won't waste excess energy from leaving the heating on too high, for too long.' 

However, be wary of moisture building up around windows due to a lack of fresh air, which can build up nasty toxic black mould.