A little informal research on the white vs. dark car theory conducted this morning. All readings were taken on the roof of the vehicles using a non contact thermometer. Internal measurements would have been a little hard to explain as readings through the glass are biased and I don't have permission to enter other people's cars and SUVs. Colors refer to color of vehicles.
1. 7:45 am, overcast, ambient sun temperature 71F a. white 70F b. white 70F c. black 73F d. dark blue 73F e. dark blue 74F f. dark green 74F 2. 9:10 am, partly sunny, ambient sun temp. 77F a. white 87F b. white 83F c. black 98F (same as in 1, but in partial shade) d. black 110F (not in shade) e. dark blue 118F f. dark green 116F 3. 12:10pm, sunny, ambient sun temp. 81F a. white 107F b. white 109F c. black 145F d. black 145F e. dark blue 143F f. dark blue 143F g. dark green 146F 4. ranges: white 70-108F black 73-145F dark blue 73-144 dark green 74-146 So the white car roof temperature was about 37F lower than the black, dark blue or dark green, quite a bit more than my estimate. But, since we don't travel on top of the car, these numbers are less informative than if they were correlated with internal measurements. One interesting side note is the potential for offsetting CO2eq forcing from making all surface passenger vehicles in the world white. Assuming one billion vehicles (cars, busses and trucks), an average reflectable surface area of 50SF per vehicle, and a starting albedo of 0.2 going to 0.8, the estimated area would be around 1800 square miles or about enough to offset 7% of the global GHG forcing expected to be added in 2009 (pre-recession estimate). These are very fuzzy numbers as most of the vehicles are out of the tropics and wouldn't receive as much sunlight as in the case of a tropical desert with generally clear skies. And of course, like with the roofs and pavement, the offset only occurs as long as the surface exists with that level of reflectivity, while the CO2eq forcing will be around much longer, from decades to centuries. So, should EPA include tax credits for purchases of white vehicles along with all the other tax incentives to encourage the CO2eq offset as well as lowered emissions from reduced A/C? And as for the clunker program, a clunker is a clunker, but should they and new cars also have color ratings? ----- Original Message ----- From: "Alvia Gaskill" <[email protected]> To: "geoengineering" <[email protected]> Sent: Thursday, May 28, 2009 6:15 AM Subject: Re: [geo] Re: Fwd: White/Cool Roofs Memo to MEF (Major Economies Forum) > http://cosmos.bcst.yahoo.com/up/ylocalnews;_ylt=Au35Abw4T5NsZkt91yh3xGKr_aF4;_ylu=X3oDMTFhdDVrbm50BHBvcwMzBHNlYwN5bl9yXzNzbG90X3ZpZGVvBHNsawN2aWQtZXYtbGluaw--?ch=4226712&cl=13692400&lang=en > > Climate Change Video:White Paint A Weapon Against Climate Change? CBS 13 / > CW 31 Sacramento > > Caif. TV reporter on top of the roof of the TV station discusses the > advantages of white roofs in reflecting sunlight. Notes that white roofs > for commercial buildings are required in Calif. A more balanced and > accurate report than from the CBS Early Show that I renamed the Morning > Show. Morning, Good Morning, Early, Today, it's all the same. One person > commented that I shouldn't be watching this crap, but bad as it is, > millions > of people do and their opinions are largely formed by what they see and > hear > on these general interest programs, moreso now with the demise of print > newspapers. The local TV news briefly mentioned Chu's statement on this, > so > it has been fairly widely disseminated, although I don't think the public > or > the media actually understands the potential limits to it or the time > scales > and effort involved. > > I've also attached some pictures I shot in early April of the roof of a > local Sam's Club warehouse building in Durham, NC (501, 502, 503) to > illustrate some of the problems with white roofs, namely that while they > start out white, they don't stay that way. This particular building is > part > of a large shopping center that sits on the site of the former South > Square > Mall for those of you familiar with the area. A Target and some other > stores make up the rest of the structure which is nearly a quarter of a > mile > from one end to the other. It's about 5-years old and I estimate the > total > roof area to be around 300,000 SF. > > When the building was new, the roof was quite white and shiny, much like > virgin white polyethylene sheeting (see my Roomba videos at weatherman2050 > on YouTube for comparison shots of new and used white plastic.) Today, > however, the roof is a dingy light gray in color which seems to revert > back > to white again when it rains or of course, snows. I don't think > management > makes any effort to clean the roof, relying on the wind and rain to do the > job. To be fair about this, I've seen the roofs of other commercial > buildings in this area that do appear white, but without knowing their age > or when the roof was installed which may be different, it is difficult to > tell the history. > > Also shown are shots of the nearby sidewalk where the pictures of the roof > were taken. The roof is now about the same whiteness as the concrete > sidewalk (505), but brighter than the adjacent asphalt (506). According > to > the Akbari/Rosenfeld plan, as I understand it, degradation of the roof > albedo to around 0.6 total solar is factored into the estimates for the > lifetime of the roof amd associated reduced CO2eq forcing and washing is > not > a requirement. Correct me on this if I'm wrong guys. The Sam's Club roof > is still probably within the 0.6-0.8 range, although without measurements, > it is impossible to know for certain. > > Most commercial buildings have flat roofs, but as Akbari/Rosenfeld > indicates, residential roofs are sloped. In NC and throughout most of the > country, home roofs tend to be slate gray or black, red or some other dark > color. Since homeowners don't want white roofs (or white cars either) due > to the fact that when they get dirty it is much more noticeable, roofs > made > of darker materials that reflect more light in the near (solar) IR are > proposed for them. > > I once tried an experiment where I completely covered my car in aluminum > foil (no pictures available, unfortunately) to see the effect on inside > temperature. It did make a difference of around 10-15 degrees F. White > painted metal on the roof or hood of a car is quite a bit cooler than > darker > colors, though, at least 10-15degrees F. White car advocates should note > that a great deal of the heating in the passenger compartment is through > the > windshield and windows and depends on the sun angle, so white paint alone > won't solve the problem. > > Cars are a lot like little houses, with windows, roofs and doors. The > foam > material in the roof known as the headliner or roof liner is analogous to > the insulation in the attic of a home. If it can be shown that > significant > reductions in GHG emissions are possible by reducing the heat gain inside > a > vehicle, the type headliner material may be as important or more so than > the > exterior paint color. Those expandable Al windshield sun shades also help > and keep the interior from getting as hot as it would otherwise, requiring > less AC to cool the car on startup. > > > > > ----- Original Message ----- > From: "Alvia Gaskill" <[email protected]> > To: "geoengineering" <[email protected]> > Sent: Wednesday, May 27, 2009 8:50 AM > Subject: [geo] Re: Fwd: White/Cool Roofs Memo to MEF (Major Economies > Forum) > > > > Predictably, the media is already misrepresenting and ridiculing the > proposal from the Energy Sec'y. On the CBS Morning Show (before they > start up with the cooking, lose weight segments and celebrity > interviews), co-host Harry Smith mentioned before a break that the > plan would emulate the light colored roofs of Mediterranean countries > and that roads would be painted white. Julie Chen then chirped in > that the roads wouldn't stay white very long in NYC. She then said it > would however, be good for manufacturers of sunglasses. Yuk yuk yuk. > Now just imagine how stratospheric aerosols, OIF, or cloud whitening > would be treated. > > On May 26, 5:31 pm, Alvia Gaskill <[email protected]> wrote: >> The 11-year offset from cars is quite misleading considering how >> difficult it would be and how long it would take. I still can't get >> over calling this geoengineering when the term has such a negative >> connotation. However, it does fit my definition of mitigating warming >> without reducing source emissions. I also would still need to be >> convinced that having the government purchase white colored cars would >> make any difference at all. >> >> http://news.yahoo.com/s/afp/20090526/sc_afp/climatewarmingusbritainchu >> >> US wants to paint the world white to save energy >> 1 hr 35 mins ago >> >> LONDON(AFP) (AFP) – US Energy Secretary Steven Chu said Tuesday the >> Obama administration wanted to paint roofs an energy-reflecting white, >> as he took part in a climate change symposium in London. >> >> The Nobel laureate in physics called for a "new revolution" in energy >> generation to cut greenhouse gas emissions. >> >> But he warned there was no silver bullet for tackling climate change, >> and said a range of measures should be introduced, including painting >> flat roofs white. >> >> Making roads and roofs a paler colour could have the equivalent effect >> of taking every car in the world off the road for 11 years, Chu said. >> >> It was a geo-engineering scheme that was "completely benign" and would >> keep buildings cooler and reduce energy use from air conditioning, as >> well as reflecting sunlight back away from the Earth. >> >> For people who found white hard on the eye, scientists had also >> developed "cool colours" which looked to the human eye like normal >> ones, but reflect heat like pale colours even if they are darker >> shades. >> >> And painting cars in cool or light colours could deliver considerable >> savings on energy use for air conditioning units, he said. >> >> Speaking at the start of a symposium on climate change hosted by the >> Prince of Wales and attended by more than 20 Nobel laureates, Chu said >> fresh thinking was required to cut the amount of carbon created by >> power generation. >> >> He said: "The industrial revolution was a revolution in the use of >> energy. It offloaded from human and animal power into using fossil >> fuels. >> >> "We have to go to a different new revolution that can severely >> decrease the amount of carbon emissions in the generation of energy." >> >> > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
