I've been lurking on the board for a while, love the board, and am eagerly expecting to put my name down for one in the next month or two.
But the relevant part: I propose that while in general lighter colors absorb less heat than darker colors, that for cars the difference will be negligible (at least for exterior colors). My reasoning is this:
- only 35-50% of car exterior is actually directly in contact with passenger compartment (doors, roof). Some of this would not be getting direct sunlight with any given orientation, and all these parts do have insulation between the metal and the inside.
- I expect majority of heat gain is via windows, whether they be of a type that reduced heat gain or not. So that any variation due to metal color would only impact 20% or less of total heat gain.
- I also expect that actual material of paint has more to do with reflecting/absorbing than color. I looked into different roofing materials once, and found that asphalt shingles, regardless of color, absorbed a similar amount.
So I propose an experiment. Someone who can make a Prius Round-up, bring along a couple meat thermometers. Put one in a white prius, one in a black one, and make sure they are receiving the same sunlight. Go inside, have a burger and a brew, come out, and check. Let me know so I can decide between the less heat absorbing whiter, or a cool black stealth prius.
(Oh, and I hate the "solar heat absorbing glass" description Toyota has out; me, I want my windows to reflect the heat away, not soak it in.)
Tau Zero
