Steering wheels so hot they burn your hands, interiors that cook everything inside like an oven, and scorching hot surfaces that are hot enough to fry an egg.
Welcome to car ownership in Australia.
With temperatures often reaching the mid-40s Fahrenheit in many Australian cities and 2023 declared to be the hottest year on record, some Australians are beginning to dread the summer months, especially with predictions that 2024 could break records again.
Driving in direct sunlight inside a metal and glass box inevitably gets hot, even in winter.
But that may no longer have to be the case.
The promise of a car or van that's up to 12 degrees cooler than the surrounding traffic, even before you turn on the air conditioning, is appealing.
And it's about to become a reality.
The trick is to stop exposing yourself to the sun in the first place.
We already know that a simple white paint can help.
A 2010 study by Berkeley Lab found that white and silver cars were consistently 6 degrees cooler than black cars of the same color, which meant 2 percent lower fuel costs due to reduced demand for air conditioning.
However, paint absorbs heat, metal conducts heat, and glass traps heat and creates convection currents.
Most of the heat radiates from the sun through invisible infrared rays.
And even the whitest white pigment doesn't reflect that.
Tests so far have shown that the paint has the effect of making the surface significantly cooler. Source: Nissan
New technology absorbs and reflects UV rays
Now, car maker Nissan has announced plans to introduce a new type of paint.
Traditionally, a metallic sheen and color of your choice is applied as a pigmented base coat, followed by a layer of acrylic polyurethane enamel for better adhesion.
Finally, a clear topcoat is applied to achieve a glossy, hard, durable surface.
Infrared light penetrates these layers and causes molecular vibrations, generating heat.
But Nissan is adding a new ingredient to the mix: “a synthetic composite material whose structure exhibits properties not typically found in nature.”
This new technology could be especially useful during Australia's sweltering summers. Source: Nissan
Simply put, one of these artificial metamaterials can bounce infrared light back into its surroundings before it has a chance to interact with other molecules, while the other generates electromagnetic waves to deflect heat that has already been generated.
The principle should be familiar: sunscreen applied to the human nose absorbs and reflects UV rays.
The new paint is based on similar materials such as titanium dioxide, an inert substance also often used in solar cells.
Nissan said it began a 12-month feasibility study in November. Japan Airlines' Nissan NV100 vans, which spend most of their time on Tokyo airport's hot runways, have been given new paint jobs (and are also fitted with a set of temperature sensors). The study is not yet complete.
But Nissan says the van will be up to 12 degrees cooler outside and 5.5 degrees cooler inside when parked next to another NV100 with conventional white paint.
The new paint is currently being tested on an airport runway in Tokyo. Source: Nissan
The new paint job has some drawbacks
“My dream is to make cooler cars that consume less energy,” said Dr Susumu Miura of Nissan's Advanced Materials and Processing Research Institute.
“This is especially important in the EV era, where the load from running the air conditioner in summer can have a significant impact on the state of charge.”
However, there are also drawbacks.
As long as it's white, you can choose any color you like.
Nissan also admits that its heat-reflective paint is six times thicker than standard automotive paint, which adds to the overall weight of the vehicle.
Susumu Miura says the new technology will be especially useful for electric vehicles. Source: Nissan
But it's a big improvement over similar heat-reflective paints that have started to be used in the building industry in recent years.
For smooth car surfaces, you'll need the consistency of spray paint, not roller brush, and the paint must be able to bond with a protective clear topcoat.
Nissan said it and Radicourt are working to develop thinner coatings and cheaper application processes, and also hopes to integrate metamaterials into a transparent topcoat product that would give car owners a full-spectrum color choice.
But Miura said most of the other common challenges in painting cars have been overcome.
It can withstand salt conditions and will resist chipping, peeling and scratching in accordance with existing commercial standards.
This means that this new technology may be coming our way soon.
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