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My family has gone for white cars on the theory that it reflects sunlight and therefore heats up less.

buzzerbetrayed 6y ago
I don’t feel like that’s a theory as much as it is just established science. Unless you mean “theory” in the sense that everything is technically a theory.
- waterhouse 6y ago
  Well, whether it makes a difference in practice depends on questions like: What fraction of sunlight's energy is delivered in the visible spectrum that the white paint would reflect? (Are there any significant differences in absorption of infrared or UV that would counteract it?) How much total power does that integrate to over the area of the car? At what rate does the heated exterior of the car conduct heat into the interior? Etc. I don't know these quantities myself. As I wrote the above message, it seemed possible that the effect could turn out to be very small and not worth bothering about; I vaguely remembered reading that it might be a few degrees. Well, if we google a bit: "We took two nearly identical vehicles, one white and one black, and let them bake in the hot Georgia summer sun. When we measured the interior temperature after a few hours, ... The black car’s cabin measured a scorching 130 degrees Fahrenheit, while the white car’s interior registered only 113 degrees." https://www.autotrader.com/car-video/car-color-test-are-black-cars-really-hotter-sun-video-242940 https://www.autotrader.com/car-video/car-color-test-are-blac... Ok, that is substantial.
  - oh_sigh 6y ago
    I'm disappointed they parked the cars at two drastically different angles relative to the sun, and they didn't specify if the interior was the same, or if the white car had a white interior and the black black...
Scoundreller 6y ago
> My family has gone for white cars on the theory that it reflects sunlight and therefore heats up less. Maybe the outside heats up less, but wouldn’t white reflect more light into the cabin? (Your own or nearby vehicle’s) Maybe our problem is that we don’t make black cars with white interiors.
amelius 6y ago
It also increases the albedo of the planet. Perhaps it should be mandatory.

I don’t feel like that’s a theory as much as it is just established science. Unless you mean “theory” in the sense that everything is technically a theory.

waterhouse 6y ago
Well, whether it makes a difference in practice depends on questions like: What fraction of sunlight's energy is delivered in the visible spectrum that the white paint would reflect? (Are there any significant differences in absorption of infrared or UV that would counteract it?) How much total power does that integrate to over the area of the car? At what rate does the heated exterior of the car conduct heat into the interior? Etc. I don't know these quantities myself. As I wrote the above message, it seemed possible that the effect could turn out to be very small and not worth bothering about; I vaguely remembered reading that it might be a few degrees. Well, if we google a bit: "We took two nearly identical vehicles, one white and one black, and let them bake in the hot Georgia summer sun. When we measured the interior temperature after a few hours, ... The black car’s cabin measured a scorching 130 degrees Fahrenheit, while the white car’s interior registered only 113 degrees." https://www.autotrader.com/car-video/car-color-test-are-black-cars-really-hotter-sun-video-242940 https://www.autotrader.com/car-video/car-color-test-are-blac... Ok, that is substantial.
- oh_sigh 6y ago
  I'm disappointed they parked the cars at two drastically different angles relative to the sun, and they didn't specify if the interior was the same, or if the white car had a white interior and the black black...

Scoundreller 6y ago

> My family has gone for white cars on the theory that it reflects sunlight and therefore heats up less. Maybe the outside heats up less, but wouldn’t white reflect more light into the cabin? (Your own or nearby vehicle’s) Maybe our problem is that we don’t make black cars with white interiors.

amelius 6y ago

It also increases the albedo of the planet. Perhaps it should be mandatory.