Innovation & Technology Materials & Packaging

Nissan’s ‘Cool Paint’ Will Cut Car-Interior Heat, Energy Use

The paint's cooling performance is most noticeable when a vehicle is parked in the sun for an extended period. Keeping the interior cooler helps reduce load to the A/C — and in electric vehicles, draw on the battery.

Published 4 months ago | About a 4 minute read

Image: Nissan

Nissan has been trialing a next-generation automotive paint aimed at helping lower a vehicle's ambient cabin temperature in summer and reduce the energy usage of the air-conditioning system.

Developed in partnership with Radi-Cool, a specialist in radiative cooling products, the paint incorporates metamaterial — synthetic composite materials that exhibit high solar-reflective properties.

The project is part of Nissan's pursuit of differentiated innovations that empower journeys and to help create a cleaner, more sustainable society.

In November 2023, Nissan commenced a 12-month feasibility trial at Tokyo International Air Terminal at Haneda. In collaboration with Japan Airport Terminal Co, Ltd; Radi-Cool Japan and All Nippon Airways (ANA) airport service, Nissan's “cool paint” was applied to a Nissan NV100 service vehicle operated by ANA airport services. With its large, open tarmac, Haneda airport provided the perfect environment to conduct real-world evaluation of the paint's performance under an exposed high-temperature environment.

Although still in testing phase, the results to date have been impressive. Parked side by side under the sun, a vehicle treated in Nissan's cool paint has shown up to a 21.6°F reduction in exterior surface temperatures and up to a 9°F cooler interior — compared to a vehicle featuring traditional automotive paint.

The paint's cooling performance is particularly noticeable when a vehicle is parked in the sun for an extended period. Not only is a cooler cabin more pleasant to enter — it also requires less air-conditioning run time to cool the cabin down to a comfortable temperature. This helps reduce load to the engine — or in the case of an electric vehicle, draw on the battery. In both powertrains, an improvement in efficiency is expected, as well as occupant comfort.

The metamaterial embedded within Nissan's cool paint features two microstructure particles that react to light. One particle reflects near-infrared rays in the sunlight that would typically cause molecular-level vibrations within the resin of traditional paint to produce heat.

The second particle enables the real breakthrough: It creates electromagnetic waves that counteract the sun's rays — redirecting the energy away from the vehicle into the atmosphere. Combined, the particles in Nissan's cool paint reduce the transfer of heat into surfaces including the roof, hood, doors and panels.

Image credit: Nissan

Leading the development is Dr. Susumu Miura, senior manager and expert at the Advanced Materials and Processing Laboratory at Nissan Research Center. He played a leading role in Nissan's award-winning noise-reducing acoustic material, and has dedicated much of his career at Nissan to exploring ways to make cars quieter, cooler and more efficient.

"My dream is to create cooler cars without consuming energy," Miura explained. "This is especially important in the EV era, where the load from running air-conditioning in summer can have a sizable impact on the state of charge."

While radiant cooling paint isn't new, it is typically used for the exterior of structures such as buildings and cargo containers, as well as paved ground surfaces — particularly in cities, to help mitigate the heat-island effect. But it's often very thick, requiring application by a paint roller; and without a clear topcoat, it can leave a chalky residue when touched.

Key challenges Miura said he had to consider when developing an automotive version included ensuring it could incorporate a clear topcoat, be applied via a spray gun (not a roller), and meet Nissan's rigorous internal standards for paint quality.

Since commencing development in 2021, Miura and his team have tested over 100 samples and are currently evaluating a thickness of 120 microns — approximately six times thicker than typical automotive paint. They have confirmed resistance to salt and chipping, peeling, scratches and chemical reactions; along with high color consistency and repairability. As development progresses, Miura and his team continue to explore thinner options that deliver the same level of cooling performance.

While testing and development are ongoing, Miura’s goal is that the cool paint can one day soon be offered for special orders and in a variety of colors. He said he sees strong potential — particularly for light commercial vehicle applications such as vans, trucks and ambulances that spend most of the day out driving.

While a few other carmakers have begun to test out cooling technologies, including Toyota’s solar roofs on legacy Prius models (a feature that has since been scrapped; the solar roofs now help charge the battery) and Hyundai’s just-introduced Nano Cooling Film, no approach or innovation has made it to the mainstream — an omission that the industry will hopefully rectify soon, as each year continues to be hotter than the last.