Young scientists create fabric capable of cooling interiors without air conditioning

Heat keeps pushing people indoors, raising electric bills and straining power grids. A new fabric created for cooling suggests there is another way to stay comfortable without flipping on the air conditioner.

Researchers at the University of Chicago report a fabric that stayed about 4.1 degrees Fahrenheit cooler than a sports cooling textile, and about 16 degrees Fahrenheit cooler than silk under full sun. It’s designed to work on both buildings and cars.

Po Chun Hsu of the Pritzker School of Molecular Engineering at the University of Chicago led the work.

City heat and cooling fabric

Urban neighborhoods soak up heat and radiate it back out. The U.S. Environmental Protection Agency (EPA) defines the urban heat island as a city area that runs hotter than nearby places because surfaces like roads and buildings absorb and re-emit energy, an effect that intensifies heat waves.

This matters for a lot of people. By 2050, about 68 percent of the world’s population are expected to live in cities.

Every warm object gives off invisible light that carries heat away. Scientists call this radiative cooling (RC), and it is most effective when a material lets heat escape in the mid infrared band while reflecting sunlight.

Two other terms help here. Emissivity describes how well a surface emits heat as light, and the atmospheric transmission window (ATW) is a part of the sky’s transparency that lets mid infrared energy pass through to space.

How the cooling fabric works

The team built a layered textile that balances these optical tricks.

A top layer scatters sunlight strongly, a middle layer with silver nanowires reflects unwanted infrared from hot pavement and walls, and an inner wool layer pulls body heat into the fabric for release.

The textile reflects 97 percent of sunlight and emits strongly in the mid infrared window, which is why it stays cooler even next to hot urban surfaces. 

The group tested samples under clear skies in Arizona and around Chicago. They tracked temperature with sensors, minimized stray heat, and compared against common clothing materials.

The results line up with the physics. The textile beat a broadband emitter used in sports gear by about 4.1 degrees Fahrenheit and beat silk by about 16 degrees Fahrenheit at midday, with additional on-skin tests confirming cooler readings on a volunteer’s arm.

Where it could help

Clothing is an obvious first step, but the team is also developing thicker sheets for vehicles and buildings. That approach could cut air conditioner run time on hot afternoons by passively blocking heat gain.

“We need to reduce carbon emission and make our cities carbon negative or carbon neutral, but meanwhile, people are feeling the impact of these high temperatures,” said Hsu.

Many cooling shirts work well in open fields because they reflect harsh sunlight. City streets are different, because heat also arrives from sidewalks and walls that warm up far past skin temperature on sunny days.

A textile that emits heat at all mid infrared wavelengths will also absorb that sideways and upward heat.

The new fabric focuses its emission into the sky window and blocks the rest, so it avoids soaking up warmth from buildings and asphalt.

Practical design of cooling fabric

A material for everyday wear must breathe, stretch, wash, and last. The fabric’s porous structure allows water vapor to pass, and the layers hold up under bending and machine washing.

The outer surface resists wetting, which helps it stay clean and maintain its optical performance. The inner layer can be swapped for other common fabrics without changing how the outer layers control heat.

There has been steady progress on passive cooling textiles. In 2021, a study reported that nanoprocessed silk kept artificial skin about 12.5 degrees Celsius cooler than cotton under sunlight.

Other teams explored active control of body heat with thin film devices. In 2023, researchers demonstrated a kirigami enabled, electrochromic wearable that tunes mid-infrared emission, a WeaVE paper that points to future smart garments which can warm or cool with small bursts of power.

Energy, equity, and comfort

Air conditioning is effective, yet it pulls a lot of electricity on the hottest days. Passive materials that lower temperatures by design can trim that demand without adding gadgets or noise.

Cooling access is not equal within or across countries. A fabric that reduces indoor and personal heat in simple ways gives people another option when they do not have, or cannot afford to run, a powerful cooling system.

Turning lab textiles into everyday products requires scale, cost control, and safety checks. The patent pending design suggests it can be produced with electrospinning and standard coating steps.

If thicker versions of the sheet can be manufactured at low cost, they could wrap parked cars, shade windows, or line delivery containers for food. Those uses would cut heat without adding electrical parts.

The study is published in Science.

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