Do anyone have experience with the efficiency of air ventilation cooling systems for idle parked cars? I know some cars in the more expensive range (Mercs, and BMW's and some Toyota's) have a built in function to regulate temperature function. BUT I want to know, specifically, if the solar-powered ventilation systems for cars are efficient in terms of the rate of exchange of hot air with cooler outside air. And if not how can one try to increase this speed of exchange?

Background: Basically it is said that it is a small vent that enables you to ventilate air from idle/ parked cars by mounting the small contraption to your car window. It uses solar energy to run a low voltage fan that exchanges hot air from inside of the vehicle with cooler outside air.

The reason for my question is to find out if it is worth while to purchase one of these for everyday use in hot countries like South Africa. I came accross some bad reviews of people saying it is a dud, and it only makes the hot air flow around in the car, turning it into something like a convection oven.

  • \$\begingroup\$ I saw a car in Paris more then twenty years ago that had two fans and small solar cells in the roof. \$\endgroup\$ – Oldfart Apr 15 '18 at 16:35
  • \$\begingroup\$ The old struggles of frying in your car is so real, that I actually think there should be a built in system installed for all cars to cool them down. Almost like a temp regulator :) \$\endgroup\$ – Michelle Apr 15 '18 at 16:43
  • \$\begingroup\$ @Mic: No, there shouldn't. I wouldn't want to pay for something like that. People who live in hot sunny deserts might be willing to, but lots of people live in places where the cost isn't worth it. \$\endgroup\$ – Olin Lathrop Apr 15 '18 at 16:52

Yes, these things exist. Here is one example:

These reflective screens are very common, and available from many vendors. The image above was lifted from https://www.weathertech.com/techshade/?gclid=EAIaIQobChMI7Yaph9-82gIVhITICh0AcwPbEAQYASABEgJ6ofD_BwE, which is just one example of the many resulting from the first google search I tried.

I go to Phoenix AZ every summer, and pretty much everyone seems to have something like that. You see these things deployed in many parked cars.

  • \$\begingroup\$ That's not a cooling system; it only slows the rate of heating. \$\endgroup\$ – Russell Borogove Apr 15 '18 at 17:05
  • \$\begingroup\$ @russell just like an undersized a/c \$\endgroup\$ – PlasmaHH Apr 15 '18 at 17:08
  • \$\begingroup\$ @Russell: It's a cooling system in that the result is cooler with the system deployed than without. If you were to deploy this system in a car that had stabalized at a high temperature without it, then it would indeed cool. The car would lose more heat power than it gained, until its temperature dropped to a new stable level. That's no different than other cooling systems. This is a passive rather than active system, but then the OP never specified that. \$\endgroup\$ – Olin Lathrop Apr 15 '18 at 17:12

Not the answer you're looking for? Browse other questions tagged or ask your own question.