Silver and white cars are cooler, says study

Oct 25, 2011 by Nancy Owano report
Black and silver experimental vehicles parked facing south in Sacramento, California on July 17, 2010.

(PhysOrg.com) -- From an environment standpoint, silver and white cars are cool; black cars are not. Researchers at the Berkeley Lab Environmental Energy Technologies Division (EETD) say that the color of your car affects your car's fuel economy and how seriously you contribute to pollution. A light-colored shell reflects more sunlight than a dark car shell. The cooler the color, the cooler the cabin air, and the less of a need to run your air conditioner.

Ronnen Levinson, scientist in the Heat Island Group at Lawrence Berkeley National Laboratory, is lead author of the study. The research was published in Applied Energy.

The researchers had two cars in the sun for an hour, one black and the other silver, parked facing south, in Sacramento, California. The silver Honda Civic (shell SR 0.57) had a cabin of about 5-6°C (9-11°F) lower than an identical black car (shell SR 0.05).

A silver (or white) shell would allow for a lower-capacity as well. The cars were run through five identical cycles of soaking in the sun. Each cycle consisted of an hour with the air conditioners off, followed by a half hour of cooling with the air conditioners running at maximum. The researchers measured the roof, ceiling, dashboard, windshield, seat, door, vent air and cabin air temperatures in each car along with weather conditions in the lot.

Overall, the numbers compiled in this car-color exercise found that using white or silver paint instead of black paint would raise fuel economy by 0.44 mpg (2.0 percent); would decrease carbon dioxide emissions by 1.9 percent, and reduce other automotive emissions by about 1 percent.

Air conditioning in cars not only decreases fuel economy but also increases tailpipe emissions of greenhouse gases and air pollutants. In this sense, cool-color cars influence both the driver and the planet.

Silver and white cars are cooler, says study
Comparison of roof surface temperatures measured during soaking and cooling trials.

The numbers continue to take on special significance when extended nationwide. An improvement of 2 to 2 percent in , scaled to the fleet of light-duty vehicles in the United States, represents savings of gallons of gas in the billions, if these design changes are adopted by the automotive industry.

White, silver, and other light colors are coolest, reflecting about 60 percent of sunlight but there are dark "cool" colors that can also stay cooler than traditional dark colors. When dark surfaces are needed for aesthetics or to reduce brightness, one can use special "cool-colored" materials that stay moderately cool by reflecting only the invisible component of . Solar reflective paints can decrease the ‘soak' temperature of the air in a car that has been parked in the sun.

Manufacturing designers looking more closely into recipes for pigmented coatings that maximize solar reflectance colors would find plenty of interesting research into cool colors at the Berkeley Lab. Its researchers have been looking into roofs and cool colors for some years. They have been measuring the solar spectral reflectance (reflectance versus wavelength over the solar spectrum) of commercially available pigments. The research team has developed a pigment database describing a variety of colors, including browns, blues, purples, greens, and reds, that are cool, in that they are highly reflective to near-infrared radiation.

Explore further: Idealistic Norwegian sun trappers

More information: eetd.lbl.gov/news-archives/news-cool-cars.html
eetd.lbl.gov/newsletter/nl19/eetd-nl19-1-cool.html

Paper reference: "Potential benefits of solar reflective car shells: Cooler cabins, fuel savings and emission reductions." Ronnen Levinson, Heng Pan, George Ban-Weiss, Pablo Rosado, Riccardo Paolini, and Hashem Akbari, was recently published in the journal Applied Energy (Volume 88, pp. 4343–4357).

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User comments : 26

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sherriffwoody
4.3 / 5 (19) Oct 25, 2011
You have got to be bloody joking me. They honestly didn't need to do a study to find this out. Christ, what next, a study to prove that people who drink more water are likely to pee more.
rawa1
2.8 / 5 (5) Oct 25, 2011
Nope, it's a science. You can be never sure with something, until you don't spend some money in its research... Although it apparently doesn't apply to cold fusion and similar insignificant findings...
sherriffwoody
3 / 5 (2) Oct 25, 2011
Yes but the science on this has already been done, certain colours and materials absord and radiate at differnet rates. Obviously vehicles are made of these materials and painted with these colours. And most people know from experience that getting into a black aluminum built car on a hot day is worse than getting in a white aluminum built car on the same day. Its the same as back in the day white cars be more likely to rust because they didn't get as hot during the day and therefor there body was more likely to stay wet and corrode. Black cars used to be less likely to rust. Of course anti-corrosion coatings have changed this playing field.
_nigmatic10
3.2 / 5 (5) Oct 25, 2011
There will be a study on the funding of useless studies followed by a study on the reactions to no-brainer conclusions.
sandholme
5 / 5 (2) Oct 25, 2011
So in countries where we use the heater more than the air-conditioner black is best.
Apoorv_Sharma
3.8 / 5 (5) Oct 25, 2011
The study was undertaken not to find weather or not a car's colour affects its mileage ( which is a no-brainer) but to figure out the ' by how much ' part. It turned out to be a not so much of a useless study because some billions of gallons of fuel might come into play. Usually its better to think that no finding is a waste, it might turn out to be useful on some other day in some other context.
roboferret
4.1 / 5 (8) Oct 25, 2011
In further news, a long term study from the Captain Obvious School of Technology has determined that mammals of the family Ursidae prefer to defecate in wooded areas.
javjav
5 / 5 (1) Oct 25, 2011
In winter, black cars need less time to be unzfrozen while waiting with the engine on. Also if they are warmer the engine will get the optimal temperature before white cars, less CO2 is emitted. So it depends where you live. Regarding hot days, the interior colors and the seats cloth material are much more important than the outside color in terms of the perceived temperature and air conditioned usage.
daqman
3.7 / 5 (3) Oct 25, 2011
I'm amazed by all of the negative comments here! This didn't seem obvious at all to me. I would have thought that most of the heating of the cabin area of a car would come through the windows. Certainly we put sun shades in our windows to reduce that. I would have thought that the colour of the car would make very little difference to the temperature in the car but that doesn't seem to be true, 9-11 F seems like a lot.

With a lot of these studies they seem like a waste of time but, as one of the other commenter's wrote, the point is that there is an effect that people know is happening but the research is to find out if paying attention to it matters. Which, in this case, it does.
theknifeman
3.7 / 5 (3) Oct 25, 2011
It's not so much that I am opposed to simple studies as I am at a scientist at a national laboratory spending time on it. It would have been a good high school science project. This one is right up there with birds doing mental time travel. Highly educated people with access to a national laboratory should be studying issues that actually make a contribution to society.
210
2.3 / 5 (6) Oct 25, 2011
WHA? Wha? You...you...mean...my brand new, shiny, Black, totally pimped, mink-fur-lined, Cadillac Escalade, with the 16 speakers, two DVD players, satellite radio,24 inch HUD, two televisions, five gamestations with 47 inch-flat panel displays, 500 cubic inch engine, with turbocharging, four-wheel disk brakes, with built-in OnStar, that gets one mile to each gallon of gas, is NOT cool and is not a babe magnet any more! Oh shucks...I've got to take this thing back and get a silver and white model before the babes see this thing, OMG! OMG! OMG! gasp... :-)
word-
Skepticus
1 / 5 (1) Oct 25, 2011
You have got to be bloody joking me. They honestly didn't need to do a study to find this out. Christ, what next, a study to prove that people who drink more water are likely to pee more.

What planet are you on? Facts are not facts until they are pee-reviewed and published. You may not be alive and breathing until somebody does pee-review your vital working.

ka_
5 / 5 (3) Oct 25, 2011
The results provided, or the conclusions of the study are bad:
1) The study does not take into account location - is it good to have a silver colored car in lets say Washington State where it is much colder and thus you often need heater rather than air-condition?
2) The results depends on the location of the sun compared with the car - most likely it is far from this difference in temperature in northern regions - if I recall correct a study in Norway several years ago showed only about 2C difference between black and white, and the coolest color was found to be neon green, and hottest was brown.
3) The study generalize as if the entire country have the same conditions which again is not true. We might in fact end up with increased emission if all cars changed as regions with cool weather might need to use heaters more!
4) The only study was done during a sunny day. You cannot assume the entire have only sun all the time... Again, the calculation of total energy saving is just bad.
Newbeak
not rated yet Oct 25, 2011
They could have watched a Mythbusters episode that tested this.To quote: "A fan wrote in and asked a follow up question: "Does the color of a car affect the way it heats up?". The MythBusters used two identical cars, one black the other white and left them both out in the summer heat with thermometers in both. By mid-afternoon the black car had heated up to a temperature of 135 °F while the white car topped off at 126 °F, almost 10 degrees cooler.
Newbeak
not rated yet Oct 25, 2011
Au-Pu
1 / 5 (1) Oct 25, 2011
This is interesting. But it is very limited.
Way back in the 70's or 80's others also analysed temperatures by colour.
But they used a full range of colours.
Their determination was that red was the coolest colour of the lot with the best balance of heat absorption and heat reflection.
Perhaps these people need to go back and do it all again with a larger range of colours.
Then get back to us.
third_kind
not rated yet Oct 25, 2011
Ignoring everything but emission and absorption, and assuming a flat spectral response, the ratio of solar absorptivity (sunlight absorption) to ambient emissivity (how much the car radiates at its temperature), should determine the equilibrium temperature. A shiny metal surface in the sun gets hotter than a white painted surface, even though the shiny metal reflects more sunlight - shiny metal is a poor IR emitter. Bet those Deloreans got hot.
astro_optics
3.7 / 5 (3) Oct 25, 2011
They'll ban Black cars next, as they contribute to global warming, hope the greenie/socialists don't apply the same principle to people :(
Deesky
5 / 5 (1) Oct 25, 2011
What planet are you on? Facts are not facts until they are pee-reviewed and published. You may not be alive and breathing until somebody does pee-review your vital working.

Yes pee review is an important diagnostic technique going back to Medieval times and beyond. I'm off to the pisuar...
h20dr
not rated yet Oct 26, 2011
This study is right up there with the other one posted today that cannabis causes cognitive chaos in the brain of rats. Maybe they were funded by the same people? I think they are smoking something...
James_Miller
2 / 5 (1) Oct 26, 2011
This is just stupid!Theres no way color can affect mileage! Yes black cars are hotter,wow who cares, they also get dirty easier lol The OBD 2 computers on these cars adjust the air fuel ratio as much as 1000 times a second to keep a 14.7 to 1 air fuel ratio so there is no way the emissions changed or mileage. Now if you didnt have air conditioning you would have the windows down and that burns way more than the air.There is no way any car company is gonna change a design to put a smaller HVAC unit it it .That Would cost Billions!!!
Jaeherys
1 / 5 (1) Oct 26, 2011
You know that when doing ~100km/h and assuming a V6 engine, each piston will go up and down 7-10 times a second. Thousand times a second eh?
ricarguy
1 / 5 (1) Oct 26, 2011
Everyone is missing the point of the study.
This was done in California.
CARB has a proud history of being the front runner of regulation regarding the air and is struggling to do so with "greenhouse gas" emissions as well.
California has already threatened to make the sale of new, black cars illegal in their state.
They need to spend taxpayer dollars on a government study to justify their regulation-in-the-making.
After this becomes de-facto law in CA, it will then be adopted by the "we can't be out-leftist by you" states of NY, VE, MA, etc., where it makes no sense whatsoever.
Eikka
1 / 5 (1) Oct 29, 2011
Heaters in cars don't use up extra energy because they run off of the waste heat from the engine, and the thermostat won't let hot water into the radiator/heater until the engine is sufficiently warm. That means the black vs. silver car question is irreleveant in the winter.

Though of course you could count the engine block heater, but you'd need to use it anyways because it's not wise to start cold.

The only problem with white and silver cars in the winter is that they blend in too well with all the snow and ice.
StarGazer2011
1 / 5 (1) Oct 30, 2011
maybe a stupid question, but why measure roof temperature and not interior temperature?
Jaeherys
1 / 5 (1) Oct 31, 2011
The energy has to go somewhere! Some will undoubtedly be used to heat up the interior a bit. How much though? No educated idea.