Sweltering Heat

We all know just how hot vehicles can get during the day. Infrared rays enter through the windows, and heat up the interior, along with the air inside the vehicle. Since there’s no way for the vehicle to ventilate, things get hotter and hotter. This process is similar to an oven; using the sun as the power source, instead of heating coils. Once the car’s materials are heated, the high interior temperature can last well into the evening. When you get in several hours after sunset, it can still feel stifling.

Direct sunlight is the mostly likely culprit for a car heating in this way. Cars with on-board, rechargeable batteries, and the spread of photovoltaic cells makes me wonder if there’s a way to address this.

Sun-Powered Cooling

Hot air rises, so the car’s warmest air will rest at the roof. Could we add a small ventilation system to the pillars of the car? Fans in the ventilation ductwork would draw air from the upper interior of the car, to the exterior, and ambient-temperature air would replace it through another set of ducts. I’d guess that pulling air from around the undercarriage would mean we’d get air at a cooler temperature. Or perhaps where the vehicle’s normal air intake resides?

This system could be powered through PV cells, and/or on-board rechargeable batteries, when the internal temperature exceeds the external temperature by say 10°F.

For cars with a moon or sun roof, it would be practical to integrate decorative vents there. There are possibilities for styling, to be certain. Luxury models might incorporate air conditioning to this process.

Preventative Measures

Perhaps there are other ways to reduce the car’s resting temperature?

I can imagine an additive in or coating on the car windows which would automatically reflect the incoming sunlight. Preventing the direct sunlight from entering the vehicle in the first place would greatly help to reducing the baking temperatures. Maybe to such a degree that a ventilation system wouldn’t even be needed.

However, the exterior of the car could still warm

But there may be safety considerations to this. What triggers the tinting? Could it be activated accidentally while the vehicle is in motion? That would cause a driver to lose vision of the roadways.

No-tinting would be a safe default state. Perhaps a continuous current from a rechargeable battery might be required, one that could only be delivered when the vehicle isn’t running. So when power is lost, the tint fades automatically. The power could again be harnessed from sunlight.

An additional setting within the car could regulate whether that tinting occurred at all. One might want the sunlight to enter the car during the winter to help defrost the windows. This could even be triggered by temperature sensors.

Combining Systems

In particularly hot, muggy, and sunny climates, I imagine the combination of a solar-powered ventilation system and window tinting feature would greatly reduce the interior temperatures of cars. An additional benefit comes with the system being powered by the same energy that heats the car in the first place.

I wonder how effective this would be on a large, asphalt parking lot, where the ambient air temperature is brought up because of the heat island? Will the temperatures outside and inside be pretty similar?

After checking, I find that a car’s interior can be over 20° hotter than outside. Interior temperatures can really skyrocket above even the most brutal summer heats.

Choosing a regularly-cool, shaded part of the vehicle for the air intake should make it possible to lower that interior temperature, even when it’s scorching hot. This would also make the car return to a normal temperature after it’s no longer in direct sunlight.

On Selling The Idea

I hypothesize this idea would improve driver and passenger satisfaction with their vehicles, since cars wouldn’t be nearly as hot during the summer months.

Drivers may be more willing to take trips they’d otherwise avoid when the vehicle isn’t miserable. And who likes being burnt by hot steering wheels, seat belts, and seats?

It could also help improve the fuel efficiency of the vehicles, by reducing the amount of fuel/energy needed to cool a vehicle once running. I’d love to see a study on how much energy it takes to lower the interior temperature an additional 20 degrees beyond what it is outside.

I’ve had this thought several times, after my car has baked in the heat all day, and wanted to share.