Nissan has introduced a new automotive paint that can significantly cool a vehicle parked in direct sunlight. Tests have shown that treated cars stay 21.6 °F (12 °C) cooler than untreated cars parked side by side.
We've all felt that blast of heat that enters a parked car in the sun on a hot day. Not only is it uncomfortable, it can be harmful to your health – and to your car too if you turn on the air conditioning and cool it down.
One possible solution is passive cooling paints and coatings. Engineers at Nissan Research Center have now developed a solution that includes metamaterials that help reflect the sun's rays more efficiently.
Two types of particles are embedded in the coating. One efficiently reflects near-infrared wavelengths of light, reducing the amount of heat generated in the resin of regular paint. The second particle creates what Nissan says are “electromagnetic waves” that direct more energy away from the vehicle and directly into space, similar to other radiative cooling technologies.
Nissan has been testing the coating on a Nissan NV100 service vehicle at Haneda International Airport in Tokyo since last November. The treated vehicle was found to have temperatures 21.6°F (12°C) cooler on exterior surfaces and 9°F (5°C) cooler inside the cabin compared to a normally painted vehicle parked right next to it in direct sunlight.
The basic idea of these sunlight-reflecting coatings has been around for a while, painted onto roofs to cool buildings. To do this, they are usually ultra-white and can contain ceramic, glass or titanium dioxide particles, with promising results so far.
It seems like a logical next step to start coating cars and other vehicles with them, but there are a few obstacles in the way. For one, at 400 microns, these coatings are much thicker than vehicle paint, which averages about 20 microns per layer. They also can’t have a top coat, which reduces durability and leaves a chalky residue when you touch it.
Nissan researchers were able to shrink their coating down to 120 microns—much thinner than other cooling coatings, but still much thicker than current automotive paint. More work is underway to make thinner versions with the same cooling performance. Fortunately, the current version resists chipping, peeling, scratching, chemical reactions, and other types of damage. It also maintains color consistency and is repairable.
Ultimately, the aim is to develop a version that not only keeps vehicles cool but can also have a clear topcoat, can be applied with a spray gun and ideally be available in other colours besides white.
The team explains how the coating is made in the video below.
Nissan's cool paint technology: An innovative way to combat the heat | Nissan
Source: Nissan