International. Nissan has been testing an innovative automotive paint designed to help reduce the ambient temperature inside a vehicle and decrease the use of air conditioning.
Developed in collaboration with Radi-Cool, a specialist in radiative cooling products, the paint incorporates metamaterials, synthetic composite materials with structures that exhibit properties not common in nature.
The paint cooling performance is particularly noticeable when a vehicle is parked in the sun for an extended period. A cooler cab is not only more pleasant to get into, but it also requires less air-conditioning runtime to cool the cab to a comfortable temperature. This helps to reduce the load on the engine, or in the case of an electric vehicle, to decrease battery consumption. In both types of powertrains, an improvement in efficiency is expected, as well as in occupant comfort.
The metamaterial embedded within Nissan's fresh paint features two types of microstructured particles that react to light. A particle reflects near-infrared rays to sunlight, which would normally cause vibrations at the molecular level within the resin of traditional paint to generate heat.
The second particle allows for true advancement. It creates electromagnetic waves that counteract the sun's rays, redirecting energy away from the vehicle into the atmosphere. Combined, the particles in Nissan's fresh paint reduce heat transfer to surfaces such as the roof, hood, doors and panels.
Leading the development is Dr. Susumu Miura, senior manager and expert in the Advanced Materials and Processing Laboratory at the Nissan Research Center. He played a leading role in Nissan's award-winning acoustic noise reduction material and has spent much of his career with the company 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 age of electric vehicles, where charging by running air conditioning in summer can have a considerable impact on the state of charge," he added.
While radiant cooling paint is not new, it is typically used for buildings and structures. It is often very thick, requiring application with a paint roller. Without a clear coating, it can leave a chalky residue to the touch.
One of the key challenges Miura had to consider when developing an automotive version was ensuring that it could incorporate a clear coating, be applied with a spray gun (not a roller), and meet Nissan's rigorous internal paint quality standards.
