Last post on May 23, 1999 at 2:46 PM
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Auto Body, Paint
Feb 23, 1999 (11:17 pm)
White is cooler by app 10- 20 degrees cooler than say ones that fall the middle of the visible spectrum to the darker end.
(the easiest way to explain it is not so easy, but can be viewed in terms of Ansel Adams Zone system)
The tinting incorporates metallic particles which in order of importance to me is filtering out UV light, and thus allows less heat in that hits inside masses which store and give off heat by conduction.
In practical terms, the air conditioner is in fan 2 speed and in darker vehicles in fan 3 and 4 speeds to maintain the same perceived ride comfort.
#27 of 35 Poor Man's Physics...
Mar 08, 1999 (11:31 pm)
The overall verdict is definitely correct, lighter is cooler. Having a minor in physics, I'm only a minor authority. =) Here's the deal:
White reflects light. Dark colors absorb light, then radiate the solar energy as heat. In the interior of a car, here's the results. A lot of the light that's reflected off of the light colors is reflected right back out of the windows. The dark interior absorbs that light and warms the stagnant air via conduction. Thus making the darker interior color a hotter car.
How does tinting come into play? Well, it partially reflects, partially absorbs that light. Granted, there's quite a bit of light that still makes it through (otherwise, you couldn't see *grin*), but a significant portion of that solar energy is filtered out. So, what's the difference between the tint absorbing the energy and the interior? Glad you asked. First, the surface area of the tint is smaller, so there's simply less area of the car giving off heat to the interior of the car. Secondly, the tint radiates heat in both directions, inside and outside of the car. If that were the only thing in play, your car would get hot at half the rate. As it is, it helps significantly.
So, how can people say that there's no difference between the tempatures of light and dark cars. The cheap answer is, there is no difference in how hot either car gets because they'll both peak at the same temp (although I've never experienced a temp. peak). The difference lies in how fast they'll reach that temp. Again, in most modern cars, you're not going to feel too much of a difference between a dark and light car if the interior is the same color due to the engineering / insulation of the cars. However, get two cars of differing interior colors, and I'd prefer to ride in the light colored one any hot day.
Blaikm had the right idea when he said that clear is black, but I'll go one step further, clear is pure evil and of Satan. It goes back to that surface area thing; it allows for more interior space to be heated faster psi than if your entire exterior were black.
As for things baking onto your paint, that's another matter entirely. In hot states, I doubt it really matters what color your car is, anything could possibly bake into your paint and it would definitely be more noticeable on a dark car. Dark colors also fade faster under harsh conditions, but then, I don't need to tell you that.
Having said all that, I have a dark green Solara with a dark interior living in Louisiana. Intelligence? What's that?
#28 of 35 Windows and sheet metal: which contributes more?
Mar 13, 1999 (3:12 am)
I have a question here: during a hot day, does exterior sheet metal conducts heat more than the sunlight radiating through the windows? Here I assume the window is not tinted.
In my opinion, the windows should contribute more heat than the metal conduction. The point is how much portion either part contributes. Window 70% and metal 30%? Or simply window 100% and metal none? Can you give your opinion please?
#29 of 35 lwf
Mar 24, 1999 (6:38 pm)
"The bedouines wear black so they sweat more."
Most of the bedouin men I saw in my 2 years in Saudi Arabia wore white. The women wear black, but I think that's a cultural/religious thing which has little to do with comfort. And from what I saw of their vehicles, almost all of the bedouin's pickups are without air conditioning and painted white.
Apr 12, 1999 (7:16 pm)
Here's an idea...instead of speculating about whether to buy a dark or light colored car, go to Radio Shack and buy two cheap digital thermometers. Get a type that has a display big enough to see from outside the car. Go to the dealer and tell them you are seriously considering a car, but need some information before you can make up your mind. Find a dark and light colored model of the same car parked reasonably close together and pointed in the same direction to minimize differences. Put a thermometer in each car (in exactly the same place in the car) and close the doors. Make sure you can see the displays. Hang around, look at cars, sit in the shade, etc. until the temperature stabilized in both cars (when the thermometers no longer change) and read which car is the hottest.
Then post the results here for the rest of us. Tell us the exterior and interior colors of both cars. It would be best if the exterior colors were dark vs. light, but the interior colors were the same.
As long as you are careful to keep everything but the car color the same, this would be a valid way of getting your answer.
Apr 15, 1999 (7:35 pm)
previous post great idea, but only if they have donuts & coffee. tell them you want to try it again on a cloudy day to see what the filtered radiation does. I hate dark cars, including mine. Even if it's only the outside that's hotter, I will still notice it if I try to drive with windows down and put arm out. Parked at a stoplight, all that radiating air surrounds you. I think I'm getting paranoid or else they're after me.
Apr 22, 1999 (12:36 pm)
Living in Florida and having owned both dark and light cars.......white is the way to go!!
#33 of 35 jimj
Apr 29, 1999 (8:57 pm)
One advantage of a dark car instead of white: In humid climates (like Galveston Texas), a dark color that collects heat will cause exterior water to evaporate faster and therefore minimize rust. The general wisdom in south Texas is dark color cars last longer, but light colors are cooler.
In Arizona, when the air temperature is 112, I don't know what difference the paint color makes - it's intolerably hot no matter what car you are in. Thats why air conditioning and covered parking are very popular.
May 01, 1999 (9:34 pm)
ok..m 2 cents.. my son when he was in middle school did a science fair project..took identiacal shoe boxes... painted them various colors... from black to white.. and put aluminum foil over one...then exposed them to a radiant heater.. same distance..etc. the dark colors heated much quicker and got to a higher temperature.. difference in white and black was incredible.. aluminum coated was the best.. had a digital thermometer with probes reaching in the back.. cant remember the exact data, but the differences were great.
May 23, 1999 (2:46 pm)
I carry cassette tapes in my car and it is a pain to always put them in the trunk when parked in the hot sun. I just did a series of tests using a thermometer that records the highest temperature reached during the period of test. It has an indoor unit and a probe for outdoors, so I was able to check two places under the same conditions.
I found that the seat was the hottest place, the glove compartment and top console bin next hottest, the bottom console bin compartment a bit cooler, and the winner... under the passenger seat was actually as cool as in the trunk, sometimes even a few degrees cooler. That was a surprise. I have double-checked it and every time seat would be about 128 degrees and under it would be 98 degrees.
Lucky for me, my car has a drawer under the passenger seat so I now keep tapes there.
FYI, the car is silver metallic.