Radiative cooling paint could reduce air-con load

Nissan, in collaboration with Malaysian radiative cooling specialist Radi-Cool, has developed a revolutionary paint technology and proven it can significantly reduce vehicle interior temperatures, reducing the load on cabin comfort air-conditioning with the potential for other applications such as transport refrigeration and other thermal management solutions.

“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,” said Dr. Susumu Miura, senior manager and expert at the Advanced Materials and Processing Laboratory, Nissan Research Centre.

Core to this technology is metamaterial, a type of synthetic substance engineered to have properties rarely observed in the natural world, featuring two distinct microstructures embedded within the paint that react to light.

The first particle deflects near-infrared rays from sunlight, which normally cause heat by making the resin molecules in traditional paint vibrate.

The second particle, a real gamechanger, generates electromagnetic waves that counteract the sun’s rays, redirecting the energy away from the vehicle into the atmosphere.

Rigorous testing at Haneda Airport in Tokyo compared a Nissan NV100 service vehicle coated with the new paint against a standard vehicle – and the results were notable. 

The radiative cooling paint lowered the exterior surface temperature by up to 12°C, while the interior temperature of the painted vehicle was up to 5°C cooler than the one with standard white paint.

According to Nissan, the paint (which needed to be compatible with a sprayed clear topcoat for aesthetic and protective purposes) has demonstrated excellent resistance to salt, chipping, peeling, scratches, and chemical exposure while maintaining colour consistency and repairability.

Nissan’s vision is to offer this technology as a special order option across various colour palettes, initially targeting light commercial vehicles that typically have large areas of painted surface and fewer windows than passenger cars.

Benefits include improved fuel efficiency due to reduced reliance on air-conditioning, and therefore a smaller environmental footprint, while for electric vehicles, reducing thermal load on the battery system improves range and extends battery lifespan.

Cooler vehicle interiors also improve driver comfort, leading to increased productivity and overall wellbeing.

Although currently in the testing phase, the team has evaluated more than 100 paint samples and established a baseline thickness of 120 microns, approximately six times thicker than typical automotive paint.

Efforts are now underway to develop thinner paint formulations with equivalent cooling performance.