As heatwaves become more frequent and intense, scientists are continuing to study how clothing can help people stay comfortable while reducing reliance on air conditioning.
Fit matters more than colour
Many people instinctively reach for white clothing in summer because it reflects sunlight, while darker colours absorb it.
However, the science is more complicated than that. Clothes do not only interact with heat from the sun; they also interact with heat produced by the body.
A famous 1980 study examining why Bedouins traditionally wear black robes in the desert found that black and white robes resulted in similar heat exposure.
The secret lies in the fit. Loose-fitting garments create a layer of air between the fabric and the skin. In black robes, the heated air rises through the garment like a chimney, helping to carry excess heat away from the body.
As a result, loose clothing is generally more important than colour. If you're wearing tighter clothes, lighter colours remain the better choice.
Textured fabrics such as seersucker or piqué can also help by preventing fabric from sticking directly to the skin.
Humidity changes everything
The ideal clothing also depends on whether the weather is dry or humid.
In dry heat, sweat evaporates easily and naturally cools the body. In humid conditions, however, the air is already saturated with moisture, making evaporation much less efficient.
"In terms of clothes, it's better to have a material that allows water vapour to pass through so that it doesn't block sweat evaporation," says physicist Rhett Allain of Southeastern Louisiana University.
This is why breathable fabrics become particularly important during humid weather.
Choosing the right fabric
Fabric choice has a major impact on comfort.
Natural fibres such as cotton and linen are breathable and allow heat to escape relatively easily. Linen in particular is popular in hot climates because of its large fibres and airy weave.
The downside is that both absorb moisture and can remain damp for long periods when you sweat heavily.
Synthetic fabrics such as polyester and nylon, commonly used in sportswear, behave differently. They are designed to wick moisture away from the skin and dry quickly.
Research suggests that nylon generally absorbs more moisture and has stronger wicking properties than polyester, although it can take longer to dry.
Some studies have also suggested that bamboo-based fabrics may offer a comfortable alternative because of their low heat conductivity and moisture-management properties.
Why breathable fabrics work
All fabrics trap some of the infrared heat emitted by the body. This is useful in winter but far less desirable during a heatwave.
According to research published in the Journal of the International Society of Sports Nutrition, breathable materials such as uncoated cotton, linen, nylon and polyester allow more heat and moisture to escape.
The more efficiently sweat evaporates, the more effectively the body can cool itself.
Sometimes less is more
According to environmental physiologist George Havenith of Loughborough University, the most effective cooling strategy is also the simplest.
When appropriate, wearing less clothing allows for greater evaporative heat exchange between the skin and surrounding air.
Of course, exposed skin also increases the risk of sunburn, making sunscreen and UV protection essential.
The future of cooling clothes
Scientists are developing new materials specifically designed to keep people cool.
Researchers at MIT found that ideal cooling fabrics should reflect visible sunlight while allowing infrared heat generated by the body to escape.
Their experimental materials use ultra-thin fibres that improve heat dissipation while maintaining comfort.
Meanwhile, researchers at the University of Maryland have developed adaptive textiles that physically change structure as temperatures rise, opening microscopic gaps that allow more heat to escape.
Other teams are exploring "phase-change" fabrics containing materials that absorb excess heat as they melt, helping regulate body temperature during extreme conditions.
The cooling power of water
One of the most effective cooling methods may not involve advanced textiles at all.
According to researchers, damp clothing can dramatically increase cooling because water absorbs heat from the body as it evaporates.
That same process powers the body's natural cooling system through sweating. Adding water to a scarf, hat or lightweight garment can therefore provide additional relief during extreme heat.
The verdict
The perfect heatwave outfit is not necessarily a plain white T-shirt.
For most people, the best combination is:
- Loose-fitting clothing
- Breathable fabrics such as linen or lightweight cotton
- Moisture-wicking materials during humid conditions
- Light colours when wearing fitted garments
- A damp cloth or lightweight wet garment when temperatures become extreme
In short, staying cool depends less on colour alone and more on creating conditions that allow heat and moisture to escape from the body as efficiently as possible.
Source: BBC
