Nissan trials cool paint technology

Nissan are trialling cool paint technology which contains embedded metamaterial that can lower cabin temperatures and reduce the energy usage of a vehicles air-conditioning system.

The paint has been developed in partnership with Radi-Cool, a specialist in radiative cooling products. The paint incorporates metamaterial, synthetic composite materials with structures that exhibit properties not usually found in nature.

The project forms part of Nissan’s pursuit of differentiated innovations that empower journeys and help create a cleaner more sustainable society.

Part of the project included a 12-month feasibility trial at Tokyo International Airport where Nissan’s cool paint was applied to a Nissan NV100 service vehicle operated by ALL Nippon Airways airport services.

With its large, open tarmac, the airport provided the perfect environment to conduct real-world evaluation of the paint’s performance under an exposed high-temperature environment.

Initial results have been impressive. Parked side-by-side under the sun, a vehicle treated in Nissan’s cool paint yields up to a 12-degree Celsius reduction in exterior surface temperatures and an interior that is up to five-degree Celsius cooler, compared to a vehicle finished with traditional automotive paint.

The paint’s cooling performance is particularly noticeable when a vehicle is parked in the sun for an extended period of time. A cooler cabin is not only more pleasant to enter, but also requires less air-conditioning run time to cool the cabin to a more comfortable temperature. This in turn helps reduce the load on the engine, or in the case of an electric vehicle, draw on the battery, while also improving passenger 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 as it creates electromagnetic waves, which 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 such as the roof, hood, doors and panels.

While radiant cooling paint isn’t new, it has traditionally been used for buildings and structures as it is very thick, requiring application by paint roller. Devoid of any clear topcoat in this application it will give off a chalky residue when touched.

Key challenges for Nissan’s engineers at the Advanced Materials and Processing Laboratory, Nissan Research Centre when developing an automotive version was to ensure that it could incorporate a clear topcoat, be applied via a spray gun and meet Nissan’s rigorous internal standards for paint quality.

Since commencing the development in 2021, the engineering team have tested over 100 samples and are currently evaluating a thickness of 120 microns, which is approximately six times thicker than typical automotive paint. The team continues to explore thinner options that deliver the same level of cooling performance.

Nissan sees strong potential for this technology, especially for light commercial vehicle applications such as vans, trucks and ambulances which spend most of their day out on the road.