Thermals are one solution you might reach for to keep you warm as temperatures plummet again this winter.
Are they worth investing in though? And which are the best thermals? We set out to find out how much warmer thermals keep you than simply wearing an extra layer and whether cheaper thermals do as good a job as pricier ones or whether it's worth paying out a bit more.
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The thermals we tested
We pitted the following cheaper and pricier thermals against a cotton t-shirt:
- Matalan crew neck thermal t-shirt (polyester and cotton blend) – £8 available at Matalan
- Marks and Spencer Heatgen Maximum thermal short sleeve top (wool and synthetics blend) –£22.50 available at Marks and Spencer
- Primark cotton t-shirt (100% cotton) – £7 for 3-pack available instore at Primark
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How we tested thermals
We put the cotton t-shirt and thermal tops through the following tests and measurements. They were all worn by the same body, in turn, for testing:
- We used a thermal imaging camera to detect where (if any) heat was escaping from the shirts.
- We put four temperature probes under each shirt to measure the internal temperature rise. The more the better.
- We used a temperature gun to measure the external temperature rise of each shirt. The less the better.
- We did this outdoors in a 10°C ambient temperature, wearing each shirt for 30 minutes each time.
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Which top: thermal or cotton, kept us warmest?
Outside where we did our testing, it was a chilly 10°C, the kind of temperature you might have been experiencing during your home over the recent freezing spell if you were trying to spare heating costs.
In these temperature, the cotton t-shirt extra layer just didn't cut it. Even though we measured a slight increase in the internal temperature, it wasn't enough to stop us shivering.
Both thermals, thankfully, fared much better. We didn't shiver while wearing them and both measured a more significant rise in internal temperature than the cotton t-shirt.
The cheaper polyester-blend Matalan thermal had an internal temperature rise of 3°C, while the wool-blend M&S thermal rose the temperature under the thermal by a toasty 5°C.
While the pricier thermal registered a higher temperature rise, we didn't feel as big of a difference in warmth between the two thermals compared to the difference between the thermals and cotton t-shirt.
Based on this, we're definitely recommending investing in thermals if you're after just one extra layer added warmth.
If your budget can stretch to it, a more expensive wool-blend thermal should keep you warmer. However, at nearly a third of the price, our tests found the best value for money to be the cheaper thermal, so we'll be buying one of those to re-use each time the temperature dips.
Even with a thermal t-shirt though, you might need extra help to keep warm. As you can see from the thermal image comparison above, all the tops leaked heat in the same locations, mainly the armpits and neck, showing that's where you might want to bolster extra coverage, whether you're going outside in the cold or staying in in it this winter.
Pricing and availability last checked 13 December 2022
source https://www.which.co.uk/news/article/do-cheap-thermals-keep-you-as-warm-as-pricier-ones-akMmO9F6ft4V