Film applied to windows of 2 Universe buses

Driver's seat temperature drops up to 7 C

Cooling effect to be tracked over 1 year

Nano cooling film, an advanced material that lowers vehicle interior temperatures, is applied to two police buses belonging to the 1st Mobile Unit at the Seoul Metropolitan Police Agency's Mobile Command headquarters. [Hyundai Motor Group]
Nano cooling film, an advanced material that lowers vehicle interior temperatures, is applied to two police buses belonging to the 1st Mobile Unit at the Seoul Metropolitan Police Agency's Mobile Command headquarters. [Hyundai Motor Group]

Hyundai Motor Group said Wednesday it has applied its "nano cooling film" — an advanced material that lowers vehicle interior temperatures simply by being attached to windows — to two police buses belonging to the 1st Mobile Unit at the Seoul Metropolitan Police Agency's Mobile Command headquarters.

The nano cooling film builds on the heat-reflecting function of conventional tinting film by adding the ability to radiate infrared energy from inside the vehicle to the outside. Hyundai Motor Group says it is the world's first developer of the material. The film consists of three layers: two that reflect near-infrared wavelengths from solar energy and one that emits mid-infrared wavelengths from the interior to the exterior. It can be applied to vehicles in the same way as standard tinting film.

Hyundai Motor Group said it decided to apply the film after recognizing that police buses serve as mobile field offices and rest spaces for riot unit officers for extended periods. The group noted that regulations restrict the use of heavy tinting on police buses, leaving officers struggling to carry out their duties in extreme heat.

The group applied the 90-percent-transmittance nano cooling film to the side and rear windows of two Universe buses assigned to the 13th and 14th Mobile Units. The buses were immediately deployed for riot unit operations after the installation.

Hyundai Motor Group said it expects the film to improve officers' working conditions while also reducing energy consumption by lowering air-conditioning use. The group plans to monitor the buses over the next year to verify the cooling effect and film quality before considering full-scale mass production.

Earlier, Hyundai Motor Group applied the 90-percent-transmittance nano cooling film to the large hydrogen fuel-cell bus Universe FCEV and an ultra-low-floor hydrogen fuel-cell bus produced at Hyundai Motor's Jeonju factory, then compared them against untreated vehicles. Buses fitted with the film maintained interior temperatures an average of about 2 to 3 degrees Celsius lower than those without it, with the driver's seat — which receives more direct sunlight — showing a difference of nearly 7 degrees.

Temperature test results for the nano cooling film show that vehicles fitted with the film maintained interior temperatures an average of about 2 to 3 degrees Celsius lower than untreated vehicles, with the driver's seat showing a difference of nearly 7 degrees. [Hyundai Motor Group]
Temperature test results for the nano cooling film show that vehicles fitted with the film maintained interior temperatures an average of about 2 to 3 degrees Celsius lower than untreated vehicles, with the driver's seat showing a difference of nearly 7 degrees. [Hyundai Motor Group]

Beyond improving passenger comfort, Hyundai Motor Group said it expects significant energy savings and carbon emission reductions, noting that lowering a bus's interior temperature by 1 degree Celsius requires approximately 1.6 kilowatt-hours of electricity.

In 2024, Hyundai Motor ran a campaign called "Made Cooler by Hyundai" in Pakistan — where window tinting is legally prohibited — providing the transparent nano cooling film free of charge to more than 70 drivers. The initiative led to the automaker becoming the first in the industry to hold an official technology-themed seminar at Cannes Lions 2024, the world's largest international advertising festival. The film also earned a gold and a bronze at the 2024 London International Awards and three merit awards at One Show 2025, both considered among the world's top three advertising competitions.

Lee Min-jae, a principal researcher at Hyundai Motor and Kia's Advanced Materials Research Center who led the nano cooling film's research and development, said he takes pride in having developed a technology that can offer some relief to officers struggling in the heat. "We will continue to expand real-world applications and track performance to bring the technology to its full potential," he said.

Meanwhile, Hyundai Motor Group has been carrying out a range of corporate social responsibility activities, including donating vehicles and rehabilitation equipment to the National Fire Service Hospital in Eumseong-gun, North Chungcheong Province — the country's first medical facility dedicated to firefighters — to support the health recovery and rehabilitation of first responders who risk their lives at disaster scenes.


eyre@heraldcorp.com