Nissan Cool Paint Promises Lower Cabin Temperatures

Heat-rejecting paint is nothing new on buildings and other structures that are suitable for thick, gloppy paint that is applied with a roller. But Nissan and technology partner Radi-Cool are testing a paint that can be sprayed onto cars’ sheetmetal.

This paint embeds synthetic composite metamaterial with structures that exhibit properties not usually found in nature to help reject solar heat from the roof, hood, and fenders on test cars as they rove the airport.

Last November, Nissan launched a 12-month feasibility trial at Tokyo International Air Terminal at Haneda using a Nissan NV100 van operated by All Nippon Airways (ANA) airport services. Already, there are results.

This infrared image shows a cooler car on the left compared to the one on the right. NISSAN

Parked side-by-side under the sun, a vehicle treated in Nissan's cool paint has shown yields of up to a 21.6-degree Fahrenheit reduction in exterior surface temperatures and up to 9-degree Fahrenheit cooler interior, compared to a vehicle featuring traditional automotive paint.

The effect is most pronounced when a vehicle is parked in the sun for an extended period, providing a cooler cabin to enter and less subsequent air-conditioning run-time to cool the cabin to a comfortable temperature. This is especially beneficial for electric vehicles, as it reduces the draw on the battery.

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The metamaterial embedded in the paint includes two microstructure particles that react to light. One particle reflects near-infrared rays in the sunlight that would normally produce heat. Nissan says that the second particle isthe real breakthrough: It creates electromagnetic waves that counteract the sun's rays, redirecting the energy away from the vehicle into the atmosphere.

The challenge has been to develop a version of this technology that is compatible with the demands of the automotive market. That means the ability to apply the paint with a spray gun, the ability to incorporate a clear topcoat, to meet automotive durability requirements, and to provide a satisfactory appearance.

The 120-micron paint surface applied to the test vehicles is about six times thicker than regular automotive paint and has so far confirmed resistance to salt and chipping, peeling, scratches, chemical reactions, along with color consistency and repairability. The goal is to develop paint that will continue to provide similar results with thinner coats. Nissan would also like to be able to use the technology in the full spectrum of paint colors and not just the white of the test vehicles.

“My dream is to create cooler cars without consuming energy,” explained Susumu Miura, senior manager and expert at the Advanced Materials and Processing Laboratory, Nissan Research Center. “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,” he said.

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