Cooler white roofs – no complaints there

Maybe now NOAA will get rid of all remaining rooftop climate monitoring stations or stations sited over asphalt, like this one. As for the carbon emissions issue, that remains to be seen.

Global Model Confirms: Cool Roofs Can Offset Carbon Dioxide Emissions and Mitigate Global Warming

Cool roof in SolanoCan light-colored rooftops and roads really curb carbon emissions and combat global climate change? The idea has been around for years, but now, a new study by researchers at Lawrence Berkeley National Laboratory that is the first to use a global model to study the question has found that implementing cool roofs and cool pavements in cities around the world can not only help cities stay cooler, they can also cool the world, with the potential of canceling the heating effect of up to two years of worldwide carbon dioxide emissions.


Because white roofs reflect far more of the sun’s heat than black ones, buildings with white roofs will stay cooler. If the building is air conditioned, less air conditioning will be required, thus saving energy. Even if there is no air conditioning, the heat absorbed by a black roof both heats the space below, making the space less comfortable, and is also carried into the city air by wind—raising the ambient temperature in what is known as the urban heat island effect. Additionally, there’s a third, less familiar way in which a black roof heats the world: it radiates energy directly into the atmosphere, which is then absorbed by the nearest clouds and ends up trapped by the greenhouse effect, contributing to global warming.

Today, U.S. Energy Secretary Steven Chu announced a series of initiatives at the Department of Energy to more broadly implement cool roof technologies on DOE facilities and buildings across the federal government. As part of the effort to make the federal government more energy efficient, Chu has directed all DOE offices to install cool roofs, whenever cost effective over the lifetime of the roof, when constructing new roofs or replacing old ones at DOE facilities.  Additionally, the Secretary has also issued a letter to the heads of other federal agencies, encouraging them to take similar steps at their facilities.

“Cool roofs are one of the quickest and lowest cost ways we can reduce our global carbon emissions and begin the hard work of slowing climate change,” said Chu. “By demonstrating the benefits of cool roofs on our facilities, the federal government can lead the nation toward more sustainable building practices, while reducing the federal carbon footprint and saving money for taxpayers.”

In the latest study, the Berkeley Lab researchers and their collaborators used a detailed global land surface model from NASA Goddard Space Flight Center, which contained regional information on surface variables, such as topography, evaporation, radiation and temperature, as well as on cloud cover. For the northern hemisphere summer, they found that increasing the reflectivity of roof and pavement materials in cities with a population greater than 1 million would achieve a one-time offset of 57 gigatons (1gigaton equals 1 billion metric tons) of CO2 emissions (31 Gt from roofs and 26 Gt from pavements). That’s double the worldwide CO2 emissions in 2006 of 28 gigatons. Their results were published online in the journal Environmental Research Letters.

“These offsets help delay warming that would otherwise take place if actual CO2 emissions are not reduced,” says Surabi Menon, staff scientist at Berkeley Lab and lead author of the paper.

Co-author Hashem Akbari emphasizes that cool roofs and pavements are only a part of the solution: “Two years worth of emissions is huge, but compared to what we need to do, it’s just a dent in the problem,” says Akbari, the former head of the Berkeley Lab Heat Island Group and now Hydro-Quebec Industrial Research Professor at Concordia University in Montreal. “We’ve been dumping CO2 into the atmosphere for the last 200 years as if there’s no future.”

This study is a follow-up to a 2008 paper published in the journal Climate Change, which calculated the CO2 offset from cool surfaces by using a simplified model that assumed a global average for cloud cover. The earlier paper, co-authored by Akbari, Menon and Art Rosenfeld, a Berkeley Lab physicist who was then a member of the California Energy Commission, found that implementing cool roofs and pavements worldwide could offset 44 gigatons of CO2 (24 Gt from roofs and 20 Gt from pavements).

Equivalent to Getting 300 Millions Cars Off the Road

“If all eligible urban flat roofs in the tropics and temperate regions were gradually converted to white (and sloped roofs to cool colors), they would offset the heating effect of the emission of roughly 24 Gt of CO2, but one-time only,” says Rosenfeld, who returned to Berkeley Lab this year. “However, if we assume that roofs have a service life of 20 years, we can think of an equivalent annual rate of 1.2 Gt per year. That offsets the emissions of roughly 300 million cars (about the cars in the world) for 20 years!”

In both studies, the researchers used a conservative assumption of increasing the average albedo (solar reflectance) of all roofs by 0.25 and of pavements by 0.15. That means a black roof (which has an albedo of 0) would not have to be replaced by a pure white roof (which has an albedo of 1), but just a roof of a cooler color, a scenario that is more plausible to implement.

(Photo courtesy ...) [2]Lighter colored pavement is more reflective, resulting in a cooler surface temperature. (Photo courtesy ASU National Center of Excellence for SMART Innovations)

Roofs and pavements cover 50 to 65 percent of urban areas. Because they absorb so much heat, dark-colored roofs and roadways create what is called the urban heat island effect, where a city is significantly warmer than its surrounding rural areas. This additional heat also eventually contributes to global warming. More than half of the world’s population now lives in cities; by 2040 the proportion of urbanites is expected to reach 70 percent, adding urgency to the urban heat island problem.

The Berkeley Lab study found that global land surface temperature decreased by a modest amount—an average of roughly 0.01degrees Celsius, based on an albedo increase of .003 averaged over all global land surfaces. This relatively small temperature reduction is an indication that implementing cool surfaces can be only part of the solution to the global climate change problem, the researchers say. To put the number in context, consider that global temperatures are estimated to increase about 3 degrees Celsius in the next 40 to 60 years if CO2 emissions continue rising as they have. Preventing that warming would necessitate a 0.05 degree Celsius annual decrease in temperature between now and 2070.

Thus, even modest changes should not be dismissed. “Simply put, a cool roof will save money for homeowners and businesses through reduced air conditioning costs. The real question is not whether we should move toward cool roof technology: it’s why we haven’t done it sooner,” says Rosenfeld.

Other Studies Reach Similar Conclusions

Another recent study on cool roofs, led by Keith Oleson at the National Center for Atmospheric Research (NCAR) and published in Geophysical Research Letters, found that if every roof were painted entirely white, the CO2 emission offsets would be approximately 32 Gt for summer and about 30 Gt annually. While the NCAR study used a different model, the calculated CO2 emission offsets are similar to the results from the Berkeley Lab study and provide a useful and independent verification of the expected CO2 emission offsets from increasing the reflectivity of roofs.

Some observers have pointed out that cool roofs do not make sense in cooler climates because of “winter penalties,” since cooler buildings require more energy to heat. However, the energy savings from cooler buildings usually outweighs any increase in heating costs. Furthermore, in winter, there tends to be more cloud cover; also, the sun is lower and the days are shorter, so a flat roof’s exposure to the sun is significantly reduced.

“Cool roofs have worked for thousands of years in the Mediterranean and Middle Eastern cities, where demand for air conditioning is low,” says Akbari. “If you have a cool roof on your house, that will reduce your energy use from air conditioning and it’s a gift that keeps on giving for many, many years, for the life of the roof.”

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research for DOE’s Office of Science and is managed by the University of California. Visit our website at www.lbl.gov/ [3].

The surface of a black roof (left) heats up 78F above the air  temperature, while the surface of a white roof (right) heats up only  12F. Additionally, with a black roof, far more heat flows both to the  city and into the atmosphere (arrow lengths are proportional to energy  radiated). [4]The surface of a black roof (left) heats up 78F above the air temperature, while the surface of a white roof (right) heats up only 12F. Additionally, with a black roof, far more heat flows both to the city and into the atmosphere (arrow lengths are proportional to energy radiated).

Additional information:


Article printed from Berkeley Lab News Center: http://newscenter.lbl.gov

URL to article: http://newscenter.lbl.gov/news-releases/2010/07/19/cool-roofs-offset-carbon-dioxide-emissions/

URLs in this post:

[1] Image: http://newscenter.lbl.gov/wp-content/uploads/roof-solano-gov-center-CEC.jpg

[2] Image: http://newscenter.lbl.gov/wp-content/uploads/Cool-Pavement-ASU.png

[3] http://www.lbl.gov/: http://www.lbl.gov/

[4] Image: http://newscenter.lbl.gov/wp-content/uploads/White-Roof-Alliance-single-10.png

[5] here: http://energy.gov/news/9225.htm

[6] Cool Roof: http://videoglossary.lbl.gov/2009/cool-roof/

[7] “Radiative forcing and temperature response to changes in urban albedos and associated CO2 offsets”: http://www.iop.org/EJ/article/1748-9326/5/1/014005/erl10_1_014005.html

[8] here: http://www.energy.ca.gov/2008publications/CEC-999-2008-020/CEC-999-2008-020.PDF

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181 thoughts on “Cooler white roofs – no complaints there

  1. Hey, I’ve got an idea: Lets start a surface stations project to paint the black roofs and asphalt under temperature stations white. We can do it to “save the planet from global warming and offset carbon”… and it would actually work to get the global temperature record down too ….

    (I can’t decide if I ought to put a smiley on this, a /sarcoff>, or leave it as serious… )

  2. If it saves HVAC costs on gov’t buildings I’m all for it. I wonder if there is a latitude/local climate optimization of reduced heating load (black roof in winter) vs. reduced cooling load (white roof in summer).

    Hmmmm, “e ink” roofs to optimize HVAC loads? (that would be a way to recycle the 1st gen Kindles people have upgraded :) )

  3. The difference in temp shouldn’t be surprising to anyone. Its much easier to walk barefoot on concrete than black asphalt. Concrete still heats up and contributes to UHI, but not as much as blacktop/black roofs.

    The real discussion should be centered around the global effects of this.

  4. On the other hand though, from research at Columbia University, NASA/GISS seem to think that green roofs are the answer. They are so enamoured that they are even suggesting:

    “These roofs should be superior to other urban rooftops as sites for meteorological stations.”

    However the results (Daily mean temperatures) show that one of the green roofs is just as warm (biased) as the black roof at the same site compared to the ambient air temperature. Full post here.

  5. This needs Willis E. and the back of an envelope! There seem to be one or two factors which have been ignored.

  6. I’m all in favor of being cooler in summer (excluding the last two miserable New England summers)…. but Mediterranean and Middle Eastern countries don’t have the cold, snowy winters we have in North America and Northern Europe. Did they do a similar analysis to see what a “cool roof” would cost in terms of insulation and heating costs? I think we may be seeing only half the picture here.

  7. What is the difference between reflected (white surface) heat and reflected (black surface) heat? Is it at different wavelengths, the so-called greenhouse effect?

    Anyway, when the next ice age hits, all roofs will be white!

  8. Talk about taking a good idea and ruining it by spewing all that global warming propaganda.

    Put it in simple, direct, dollars and cents terms. Change your roof to one with high albedo and you will cut your costs by x%. People don’t care about imaginary climate changes; they do care about their pocketbooks. Take that message about the bottom line to businesses and you will see white roofs sprouting like mushrooms all over the place.

  9. Is there any study going on about the possibility to have black roofs in the winter and white roofs in the summer?

  10. I believe gold is a better reflector than white, and prettier also. Since our money is no longer backed by gold, let’s do the roofs and roads in gold. ;)

  11. sarc on/But wait won’t the CO2 just capture the re radiated heat and increase the warming. BBQ the earth again and again, never ending. /sarc off
    These people have just discovered conservation, hopefully the will not tax it.

  12. So last weeks heat surge in D.C. came from lack of compliance with the white roof mandates of 1 year ago?
    Chu said BP would save the planet. This endeavor may be redundant.

  13. So help me understand. There is no statistically significant warming that occurs due to UHI, but, if we color our roofs and streets (and hopefully airport runways) it will help reduce the heating effect that the statistically non-existent UHI has on global temperatures?

    Have I got that right?

  14. Edward Palmer says:{July 19, 2010 at 1:26 pm}
    “What is the difference between reflected (white surface) heat and reflected (black surface) heat? ”

    I was wondering that myself.
    Looking at the right side of the roof diagram there is a large yellow line which, I suppose, represents reflected solar energy. Why doesn’t that figure into the equation? Does it have the same properties as the incoming solar radiation? The diagram implies that it does. Where does it go? How does that affect the atmospheric temperatures?

  15. Here are some misc notes on roofs.
    The principle for conventional peaked house roofs (in Canada and other cold regions) is that the bottom of the roof deck should be the same temperature as the top in the winter. That eliminates melting of snow that can form ice dams or icicles. The ceiling of the top floor should be well insulated, which means that the temperature of the underneath of the deck (which should be the same as the temperature inside the attic space) has no (appreciable) effect on the heat load of the building underneath the roof. This means that the color of the roof surface should be immaterial to the heat load inside the building. (Note that I have no quibble with the idea of reducing the UHI.)

    Cathedral ceilings are another matter!

    IanM

  16. I like this one:

    “Additionally, there’s a third, less familiar way in which a black roof heats the world: it radiates energy directly into the atmosphere, which is then absorbed by the nearest clouds and ends up trapped by the greenhouse effect, contributing to global warming.”

    I was in fact not familiar with this sinister chain of events. The atmosphere is absorbed by the nearest cloud. Oh well… even if i ignore that mistake it’s still so wrong, for what kind of audience do they think they write this?

  17. Black roofs in winter radiate much more heat away from the house. Yes they pick up more heat in the daytime, but lose more at night as the sun is down more than it is up.

    There is no compelling reason to use any colour other than white.

    If you want solar gain, use the correct overhang on the roof and double or triple pane windows (a formula tells you if it is worth putting in triple panes or not – often not).

    The IR photo of the urban heat island was very interesting. An example of using a white roof and convective air flow to maximise evaporative cooling in order to have no additional energy used is the Lotus Temple in India. http://www.bahaindia.org/temple/comments.html (with tributes by architects complimenting the the design).

    In spite of searing temperatures most of the year, the inside is cool and refreshing.

  18. the fritz says: July 19, 2010 at 1:29 pm
    Is there any study going on about the possibility to have black roofs in the winter and white roofs in the summer?

    I think we’ve hit this before. White, in addition to reflecting more, also radiates less than black, thus less heat flow. Sort of like insulation, but not quite the same. A black roof will absorb heat on sunny winter days for 9 or 10 hours, then radiate heat from your house for 14 or 15 hours. You’re better off with white all year.

    I do wonder what effect putting white paint on mineral surfaced asphalt shingles would have on durability. I’m pretty sure what effect it would have on the warranty. Maybe I could get a grant.

  19. In what ways could a roof be made that would easily change the colour – white in summer and black in winter?

    I’m thinking a roof made like those revolving advertisement boards (trivision) or James Bond’s numberplate. It would have to be waterproof between or beneath the rotating segments. You could have a white side, a black side and the third side transparent with solar water heating tubes through each segment.

    There is already a patent for a thermochromic roof.

  20. I’ve actually considered replacing the white roof of my cabin with a dark one a few times, its been that cold the last couple of years here. Cripes, its only 2200 ft elevation in the Ozark Mountains just south of Branson, MO a ways!

    But this summer its like Costa Rica, except having had a winter. What did they do? Mix some Miracle Grow in the rain? Everything is growing like mad around here with all the moisture and warmth. For example, we have fully developed hickory nuts falling that normally are dinks in July. Used to be the hickory trees would be dropping some dinks right now, because of drought, so the rest could develop normally. Hickory nuts usually aren’t fully developed until early September, and certainly not falling until mid Sept or so.

    Better than not having any at all I admit, like its been since the January ’09 ice storm that wrecked everything around here. The volcanoes since Chaiten started it off in May ’08 did it all, related to the solar minimum, that I’m sure of.

    http://www.pnas.org/content/101/17/6341.full

    The aerosol component of an eruption, resulting mainly from the emission of SO2 and H2S, can remain aloft and potentially force climate on timescales of years, decades, or longer (29). Volcanic aerosols affect the Earth’s radiation balance, principally by reflecting sunlight back into space and cooling the planet. By serving as cloud condensation nuclei, sulfate aerosols are believed to change the microphysical structure, water content, lifetime, and extent of clouds (30). Not only the type and magnitude but also the location of an eruption are thought to determine its climatic impact.

    Yipper! That’s what I’ve observed.

  21. I love that this article is a spectacular own goal by the AGW alarmists.

    Either the UHI effect is much worse than the alarmists thought (which means that their temperature measures are screwed up and the lack of warming is much worse than they thought), or the UHI is minimal- which means that painting roofs white is pointless- more to the point, if UHI effect is minimal that means that the largest concentrations of people are not even able to raise temperatures on a local basis, which raises really big questions about our ability to affect things globally.

  22. When doing their cost-benefit analysis, I have to wonder if they have included the cost of 1)the initial coat(s) of paint plus labor, and 2)subsequent coats of paint, perhaps every few years or so (do they think paint lasts forever?).
    Additionally, they of course have to guesstimate the future energy costs, in order to figure the actual cost savings. Higher energy costs = more savings. Naturally, the Warmists are rooting for wind, solar, and hampster-generated power, meaning if they get their way, yes there could indeed be energy savings.

  23. Can I hereby claim a patent on the ‘smart roof’ which is able to reconfigure its color and ‘feathering’ in order to maximize thermal efficiency?

    In addition to immediate practical benefits, ‘smart roof’ owners will also be able to change their roofing style according to the latest political fashions and fads.

    With appropriate legislative backing, I am sure that the tax imposed on others to subsidize the production of the ‘smart root’ will not be too draconian.

  24. I’m not a climatologist or a metrologist or anything like that, just a ship’s engineer.
    During Noriega’s day, I had occasion to visit Panama quite often, and it was always hot and or humid. The agent’s office was in a nice bungalow in lawned grounds, very pleasant, always hot as hell. They had lots of air conditioners, usually some of them not working. So the windows were aways full open, even in rooms with AC. I remarked upon this to the General Manager, as we sat and sweltered in his office, with AC on and windows open. He told me, the AC equipment never last, in their environment the machines always ran on “Max”, and frequently broke down. “Nothing can cope with this heat and humidity”, he explained.
    We went outside into the garden, for some relief. Some air. As we wandered around I noticed that the roof was black tarred bitumen. “It’s that only thing that will keep out the rain” he said.
    On a whim, and without any expert knowledge, except as an engineer, I told him that if he painted his roofs solid white, as white as he could get, he’d probably reduce the internal temperatures by about 3 degrees C.
    We gazed around. Every building in sight had black or very dark coloured roofs.
    So I left, and later he phoned to tell me that he had done it, taken my suggestion to heart, painted the roof white and the internal temperature
    had indeed dropped by 3 degrees, even more. So he’d taken the bull by the horns, ordered a full set of new AC machines, and instituted an “all windows tightly closed “ regime. (imposing regimes was easy in those days in Panama, although he was indeed a kindly man, my manager that is, not Noriega!) .
    The next time I visited, it was to a completely different office, cool, low humidity, happy staff.
    The next time I visited Panama I noticed that several other buildings had begun to paint their roofs white.
    So perhaps that university could have saved a lot of sponsor’s money by just asking me.
    White roofs work.

  25. I’m not a climatologist or a meteorologist or anything like that, just a ship’s engineer.
    During Noriega’s day, I had occasion to visit Panama quite often, and it was always hot and or humid. The agent’s office was in a nice bungalow in lawned grounds, very pleasant, always hot as hell. They had lots of air conditioners, usually some of them not working. So the windows were aways full open, even in rooms with AC. I remarked upon this to the General Manager, as we sat and sweltered in his office, with AC on and windows open. He told me, the AC equipment never last, in their environment the machines always ran on “Max”, and frequently broke down. “Nothing can cope with this heat and humidity”, he explained.
    We went outside into the garden, for some relief. Some air. As we wandered around I noticed that the roof was black tarred bitumen. “It’s that only thing that will keep out the rain” he said.
    On a whim, and without any expert knowledge, except as an engineer, I told him that if he painted his roofs solid white, as white as he could get, he’d probably reduce the internal temperatures by about 3 degrees C.
    We gazed around. Every building in sight had black or very dark coloured roofs.
    So I left, and he phone to tell me that he had done it, and the internal temperature
    had indeed dropped by 3 degrees, even more. So he’d taken the bull by the horns, ordered a full set of new AC machines, and instituted an “all windows tightly closed “ regime. (imposing regimes was easy in those days in Panama, although he was indeed a kindly man, my manager that is, not Noriega!) .
    The next time I visited, it was to a completely different office, cool, low humidity, happy staff.
    The next time I visited Panama I noticed that several other buildings had begun to paint their roofs white.
    So perhaps that university could have saved a lot of sponsor’s money by just asking me.
    White roofs work.

  26. Basically a ship that has already sailed. Use google maps on the satellite view and take a look at flat roofs in cities esp large buildings.

  27. Well, you may not have to paint your roofs white just yet if you live in a sub-tropical or warmer area. Look at http://discover.itsc.uah.edu/amsutemps/execute.csh?amsutemps
    today. Near surface layer is 0.05F lower and sea surface is 0.26F lower than same date last year. So global temperatures are heading “south” and it will be interesting to see what Dr Roy Spencer’s graph shows for July 2010. Any predictions for the rest of 2010 and what it may do to the “warmest ever” year on record forecasts?

  28. In both studies, the researchers used a conservative assumption of increasing the average albedo (solar reflectance) of all roofs by 0.25 and of pavements by 0.15

    The Berkeley Lab study found that global land surface temperature decreased by a modest amount—an average of roughly 0.01degrees Celsius, based on an albedo increase of .003 averaged over all global land surfaces.
    ===========================================================

    Reverse engineering this and rounding it off

    if .003 = 0.01 C

    then 0.3 = 1 C

  29. Aren’t the AGW people shooting themselves in the foot here. This study just confirmed that cities are heating up because of their black roofs, showing that CO2 plays a much smaller part in global warming than they claimed. Thankyou AGW activists!

  30. @ John Peter says:
    July 19, 2010 at 2:29 pm

    Well, you may not have to paint your roofs white just yet if you live in a sub-tropical or warmer area. Look at http://discover.itsc.uah.edu/amsutemps/execute.csh?amsutemps
    today. Near surface layer is 0.05F lower and sea surface is 0.26F lower than same date last year. So global temperatures are heading “south” and it will be interesting to see what Dr Roy Spencer’s graph shows for July 2010. Any predictions for the rest of 2010 and what it may do to the “warmest ever” year on record forecasts?

    Not to be nit-picky, but the Judeo – Christian calendar ( or any other human calendar ) is of little consequence to the planet or the universe. So comparing “this date in history” with any other present or future date in regards to the weather or climate is pointless and irrelevant.

  31. >> E.M.Smith says:
    >>July 19, 2010 at 1:13 pm
    >>Hey, I’ve got an idea: Lets start a surface stations project to paint the black roofs and >>asphalt under temperature stations white.

    That was my immediate thought but it wouldn’t work … it would just be another excuse to add more warming “corrections”.

  32. Mike, If I’m reading it right, they just explained 1C in warming, and just explained all of global warming.
    ===========================================================

    In both studies, the researchers used a conservative assumption of increasing the average albedo (solar reflectance) of all roofs by 0.25 and of pavements by 0.15

    The Berkeley Lab study found that global land surface temperature decreased by a modest amount—an average of roughly 0.01degrees Celsius, based on an albedo increase of .003 averaged over all global land surfaces.
    ===========================================================

    Reverse engineering this and rounding it off

    if .003 = 0.01 C

    then 0.3 = 1 C

    If a 0.3 increase in albedo lowers temperatures 1C just by going from black to white, then black roofs, streets decreases albedo 0.3 and accounts for 1C increase in temperature.

    I expect John to remind me I’m math challenged any minute now. lol

  33. What will be amusing is seeing what sort of adjustment Jim Hansen and Gavin Schmitt makes to the surface stations for UCI “Urban Cold Island” effects when all the buildings are painted white.

  34. Two years of CO2 caused warming is a vanishingly small number. Painting roads white would certainly be good for Ray-Ban’s sales but maybe not for public safety. Auto accidents kill over a million people a year, worldwide. Roofs get dirty and dirt is almost never white.

  35. If we change everything to white we will increase energy in cold weather warming our homes and vehicles. It will also cause more danger due to icing conditions on the roads!!

    I am sure y’all can think of other unintended consequences from the WHITE idea.

  36. It’s obvious that by getting rid of the UHI effect in the instrumental readings, global warming will disappear… duh!

  37. where did all the heat go?

    Black roofs = energy stored during the day and released at night
    white roofs = little energy stored as incident radiation instantly reflected

    So why does CO2 not capture reflected day time radiation from white roof?

  38. Better get some shares in the titanium dioxide (TiO2) industry… before the demand goes exponential.


  39. Bill Marsh says:
    July 19, 2010 at 1:47 pm
    So help me understand. There is no statistically significant warming that occurs due to UHI, but, if we color our roofs and streets (and hopefully airport runways) it will help reduce the heating effect that the statistically non-existent UHI has on global temperatures?

    Have I got that right?

    Seems to me Berkley just proved that UHI and land use is a significant contributor to global warming. Hard to know how much without understanding the pre-urbanization albedo, but just from the rought calcs they present it seems reasonable that it could explain all of it.

  40. I guess the funny part is that paint solvent are petroleum based… if they want to pain the world in white they will need to extract more oil from the ground.

  41. Painting roofs of tall buildings in large cities with a high rise profile white (in cities such as New York or Tokyo for example) has less of an effect on the local climate because the heating effect from a dark roof is confined primarily to the top floor or two. For such cities building color probably has a greater effect on urban temperatures than rooftop color and the use of smart glass clad buildings in such cities may be even better than having light building colors.

  42. Heyyy, you need a punch in the kisser? This is our turf. Find your own comedy genre.

  43. Thanks but no thanks. Our nighttime temps in NE Oregon are still in the 40’s. Without my black roof, I would be turning the heat on in SUMMER!!! And I sure as hell need it in winter.

  44. Invest in Titanium dioxide,

    Titanium dioxide is the most widely used white pigment because of its brightness and very high refractive index (n = 2.7), in which it is surpassed only by a few other materials.

    JT

  45. “increasing the reflectivity of roof and pavement materials in cities with a population greater than 1 million would achieve a one-time offset of 57 gigatons ”

    One-time offeset? Wtf?? How does that work?

  46. I reject the entire AGW theory and I don’t see any reason why should take this “solution” to a non existing problem seriously.
    There is no justification for any solution if the problem is non existing.
    Besides that, I rather live in a nice warm city than a cold one.

  47. tallbloke says:
    July 19, 2010 at 4:17 pm
    “[...]One-time offeset? Wtf?? How does that work?”

    I guess it gets dirty after a while.

  48. How about they spend money on more important things that white roofs? Besides, warming isn’t happening. Cooling is.

  49. the video I posted is Monckton laying out the case of Chu wanting roofs painted white.

    I omitted a title

  50. Fancy that; The Lawrence Berkeley National Lab; having delved into the inner recesses of the atomic nucleus; has now determined that white paint reflects more light than Tar Blacktop; and all these years, builders have been building houses with black tar paper roofs.

    And here I thought that was so they would burn up faster than a tile roof would; and all the time it is that sneaky white paint.

    Was it Tom Sawyer or Huckleberry Fin, who discovered the value of whitewashing?

    I remember years ago when I traded in my Porsche 911-T for a Dodge Van; I picked the van coloring by walking around parking lots and putting my hand on cars; in a hot California Sun. Without exception; all metallic finish paint jobs were hot as hades; and the coolest I found was White paint; with lemon yellow a close second. So I went with a White yellow two tone paint job. My offshore fishing boat that I bought to tow with the van, was also a white and yellow paint job.

    Now I know why I couldn’t find a boat with black painted decks.

    Isn’t it wonderful what scientific breakthroughs we are getting for our tax dollars.

  51. @ stevengoddard says:
    July 19, 2010 at 1:22 pm
    I keep my roof white all winter. The white color keeps the house cold, raising the heating bills.”

    So do I. It’s called snow. :))

  52. {Polar Ice Cap says:
    July 19, 2010 at 1:24 pm
    How much do you save on air conditioning in the summer compared to how much more you will spend on heating in the winter?}

    P I C, i design heating and cooling systems, it is ALWAYS less energy to heat a home then to cool it to modern North American standards. If you have no cooling, the upcharge in your heating should be minimal if your insulation package is good. As stated in the article, for those of us in the NH, winter heat gain is barely registered from the sun.

    This is an idea that has been used in many parts of the world for a very long time with great results.

    Low hanging fruit!

  53. Well instead of putting solar stations in space, and beaming the energy down here; why not use that space power plant to run a huge set of lasers or other EM radiation generators that create just those LWIR wavelengths that CO2 absorbs, and phase lock to the natural radiation and cancel it out; in Bose noise cancellation fashion; so we neutralize all the LWIR in the atmosphere that CO2 can absorb.
    That should fix the CO2 problem.

  54. {Kay says:
    July 19, 2010 at 4:59 pm
    @ stevengoddard says:
    July 19, 2010 at 1:22 pm
    I keep my roof white all winter. The white color keeps the house cold, raising the heating bills.”

    So do I. It’s called snow. :)) }

    Kay, actually snow is a great insulator, think igloos. If you have snow on your roof when it is minus 15 outside, it is actually helping to keep your heat in. You can always tell which homes have a good insulation package, as their roofs are the last to have snow on them.

  55. The problem is that there is a LOT of flat urban roof. If you paint it all white, you might end up raising the albedo too much. For example, how many acres of flat roof space is there in Los Angeles, San Diego, Phoenix, Las Vegas, El Paso, Albuquerque, Dallas, etc. ? Now consider the appearance of that many acres of ice at those latitudes. Now add in all the flat roof space in the entire country.

    Maybe it would be better to make them a color that more closely matches the summer albedo of the natural vegetation of the region of that city.

  56. White roofs do NOT raise your heating bills in winter. In winter, the farther North you go, the less impact a white roof has in winter because:

    1. As you get father North, the sun angle is lower anyway and you get very little heating on a flat roof in winter from the Sun.

    2. As you get farther North, the days are much shorter in winter and daylight hours when you could possibly get any heating on that roof are very few, maybe an hour or two.

    3. Your roof is probably white anyway from snow.

  57. {dan says:
    July 19, 2010 at 4:06 pm
    Up north we have more heating days than cooling. I’ll keep my dark roof.}

    Dan, if that theory were true, you would expect most dark roofs to melt the snow far longer then say your grass, until the “heat” of the surface was cold enough to allow the snow to settle

    . This winter take the time to see if that happens.

  58. Oh, and most elastomeric white roof coatings contain ceramic insulation spheres that actually add insulation to your roof giving you better heat retention to offset any difference.

  59. dwb says:
    July 19, 2010 at 3:39 pm
    Seems to me Berkley just proved that UHI and land use is a significant contributor to global warming.
    ============================================================

    Using their numbers, they are saying that all of global warming is caused by UHI.

    If temps have increased about .7C because of global warming.

    Their numbers say it should have increased 1C by UHI alone.

  60. Energy Secretary Steven Chu has been behind a number of interesting solutions but for flat roof buildings it might make more sense to install a roof top garden or greenhouse. A white painted surface will pick-up soot from exhaust etc.

    Getting rid of the asphalt road surface makes fixing potholes and roads more expensive. Asphalt is also recycled and essentially the heavy residue of the oil refining process – a waste product. I guess it could be surfaced with a clear sun block ;)

  61. crosspatch says:
    July 19, 2010 at 5:09 pm
    “Maybe it would be better to make them a color that more closely matches the summer albedo of the natural vegetation of the region of that city.
    Hmm I wonder if painting surfaces green would be any better than black. Planting roof gardens seems like a good idea – just as long as you don’t plan to use them as weather stations too. I posted this link in the first few comments, but I think it is worth repeating:

    http://diggingintheclay.wordpress.com/2010/07/17/thermal-absorption-a-black-and-white-and-green-issue/

  62. Speaking as someone who does a fair amount of desert camping, metalized is hotter than white. Put a mirror out in the full sun for a few hours around noon. That thing will be HOT. Same with a chrome bumper. Paint it white and it is much cooler. That is one reason why all the pipe for my desert shade structures is white. I got tired of burning my hands on the silver metal pipe.

  63. One other thing about a white roof in a Northern climate … white reflects in both directions. It is also reflecting heat that would be lost at night through radiation into space back into your house. So if you have 16 hours of night and 8 hours of day, that black roof is an efficient radiator into space for twice as many hours as it can be a collector of solar heat. If you paint it white, it is a much less efficient radiator. It will save you money in both heating AND air conditioning.

    Still, I would go with some kind of a greenish brown or something, not stark white.

  64. This is a great idea; http://www.osti.gov/energycitations/index.jsp

    The Energy Citations Database (ECD) provides free access to over 2.6 million science research citations with continued growth through regular updates. There are over 221,000 electronic documents, primarily from 1943 forward, available via the database. Citations and documents are made publicly available by the U.S. Department of Energy (DOE).

    ECD includes scientific and technical research results in disciplines of interest to DOE such as chemistry, physics, materials, environmental science, geology, engineering, mathematics, climatology, oceanography, and computer science. It includes bibliographic citations to report literature, conference papers, journal articles, books, dissertations, and patents.

    Agency Information
    ECD was created and developed by DOE’s Office of Scientific and Technical Information with the science-attentive citizen in mind. It contains energy and energy‑related scientific and technical information collected by the Department of Energy (DOE) and its predecessor agencies, the Energy Research & Development Administration (ERDA) and the Atomic Energy Commission (AEC).

  65. This idea of roof lawn and garden: Problem is getting a mower up there, to say nothing of water, fertilizer, dirt, etc, plus having to substantially reinforce most roofs to handle a soaking wet 12″ deep or more layer of dirt. You’d have to water it nearly constantly as anyone who has planted anything in a container knows. Then there is root intrusion into the roof and so on. And don’t forget the bugs. It’s an astoundingly Stupid idea. Besides it’s been done before – Sod houses in the plains, remember?

  66. Bird poop is white. Just set up bird feeders on the rooftops and the problem takes care of itself…

  67. “However, if we assume that roofs have a service life of 20 years, we can think of an equivalent annual rate of 1.2 Gt per year. That offsets the emissions of roughly 300 million cars (about the cars in the world) for 20 years!”

    Um, so after I paint my roof white…
    When I replace my white roof with a new white roof, this will further alleviate global warming?
    *facepalm*

  68. So what’s new? Surely we’ve known all this since March 1804. From Note XXV on page 536 it seems being preoccupied with global warming is nothing new either :-)

  69. What is needed is to paint all roofs with 377 Ohm paint (120 pi). This will terminate ALL electromagnetic radiation; and reflect nothing; it will all just get sucked into a bottomless hole.

    Of course nothing on the ground would be visible from a satellite either; but who wants to be watched anyway.

  70. Curiousgeorge says:
    July 19, 2010 at 5:54 pm
    “This idea of roof lawn and garden…”

    Hanging gardens like grape vines would take the load off the roof and distribute it to the structure of building.

    lol, they already make light colored roofing material in rolls. This isn’t rocket science but its more expensive then seeds ; )

  71. Does anyone know how an unpainted tin roof compares to a white roof? I an thinking about the silvery-gray tin that is common for roofing in the USA.

  72. What does painted roofs do to mitigate all those bare rocks and sand out there. Seems like this is just more fun and games for distracting people.

    We learned long ago in Florida that white tile roofs were cooler, but that doesn’t say anything about heat energy transfer to the earth, or doubtful it contributes to a lowered albedo of the planet. By and large the earth cools at night giving up the heat it absorbs during the day. If it didn’t we would have all long ago melted.

  73. This study sends up all kinds of Partially Baked Idea Science!

    First: if the global models already are worthless, with many flaws, how can there be confidence in accessory changes and the results? I would like to see some real world tests before putting any value on such studies.

    BUT a big second: we have to remember that white surfaces are also not good emitters compared to black and the buildings need to be able to shed the heat generated by energy usage in the building, which always ultimately is realized as heat energy.

    Thus, making buildings white or reflective will make it more energy intensive to remove the generated heat from the buildings. I bet the gains from less absorbed energy are going to be significantly offset by the poorer shedding of internal energy.

  74. Tommy says:
    July 19, 2010 at 2:55 pm
    “I just had an ironic thought…

    “The latest plan to battle global warming: whitewash!”

    But will there be any left after Climategate?

  75. @ John from CA says:
    July 19, 2010 at 6:23 pm

    Vine covered Walmarts, etc. ? Somehow I don’t think it’s gonna happen.

  76. I would hope the study is more comprehensive than reported since the actual construction varies throughout. It seems as though the scientists are oblivious to the facts?
    For example most homes in the northeast have a vented (to atmosphere) attic above the living space in the upper floor. I believe that new homes have vents in the peak. The insulation is in the ceiling of the upper rooms. Often the attic space is power vented to remove the hotter air from the attic with a fan that is thermostatically controlled. I increased the venting in my roof about 20 years ago and noticed that the top floors were cooler during the summer.
    Subsequently the trees have grown to provide shade in the summer while allowing the sun to shine on the roof in the winter. Cooling energy demand would be unaffected by the Lab improvements

    I know from experience that the real world is not as simplistic as suggested in the article. Of course there are significant differences in construction depending on the geographic location.
    Why is it that I am skeptical that the scientists at the Labs, have a clue about the actual construction home/building and the regional differences. If most commercial construction is flat black roofs without an “attic” above then some benefits are possible. As I recall the roof in the building I used to work had a tar seal to prevent leakage with a white stone covering that would not behave as assumed by the “scientists” at the lab. No white paint required and ?? albeto. There was a craw space above the uper floor with insulation. Would there be any benefit to paint white?

  77. Amazing. As discovered in the investigation of the CRU UEA emails, the answer is “Whitewash”!

  78. When I re-roofed my house several years ago, I went from brown shingles to light gray ones. I find the attic is cooler of course and so are the upstairs rooms, It was a freebie because of the re-roofing .
    I don’t think actually painting a roof would last very long. It would be a heck of a job. I suppose you could just pour buckets of paint at the peak of your roof and let it run down!

  79. We should also consider putting more humans on rooftops by encouraging more sunbathing. I was laying out in the park this weekend soaking up the rays and I felt sorry for the poor grass underneath my beach towel — being deprived of all that energy. Judging by how red my skin is today, I estimate that I soaked up enough solar energy to at least offset Al Gore’s carbon footprint by a few microseconds.

    Now that’s progress!

  80. Here’s something to plug into your cost-benefit analysis: top-quality non-reflective asphalt shingles cost about $75 per square (100 square feet) and are guaranteed for 20 years; reflective asphalt shingles (a very pale gray) cost about $150 per square, and are guaranteed for 40 years. Not only do I need to factor in my A/C savings, but also the time value of money, and whether or not I’m even going to live that long….

  81. Everyone agrees the Urban Heat Island effect exists and warms the Earth. On that there’s no debate, unlike the catastrophic AGW hypothesis. Clearly, the only responsible action is to plow under our major urban areas and embrace a semi-rural lifestyle for all. It’s for the planet. Don’t put up a fuss, you don’t want to make Gaia cry, do you? I can feel her tears well up even now.

  82. Many have asked — and the UMich article answers — what about the effect of high reflectance white paint on heat emission.

    TiO2 paint is effectively black in the infrared, a trick Apollo used for thermal management. Reflects sunlight, emits IR.

    Also, shiny coatings are horrible emitters… i.e. an unpainted tin or aluminum roof is hotter as it doesn’t radiate as well.

  83. Lighter colored rooftops to reduce albedo is a measure that could be implemented without a great deal of complication. Lightening paved surfaces, particularly those that handle vehicular traffic, is much more problematic. At present the only material that fills the bill as a lighter colored replacement for asphaltic concrete is concrete made with portland cement. Leaving aside the economic considerations that often mitigate against PCC, it should be obvious to anyone who’s been paying much attention for the last couple decades, that dramatically increasing the demand for portland cement at this point in the carbon demonization process is going to be a nonstarter.
    AFAIK there are no paints or coatings presently available that are durable enough to last more than a few months if applied across full lanes of AC pavement. Up here in the Great White of MN, centerline and shoulder striping, on roads that see anything but the most modest levels of traffic, are repainted mostly annually. And though they are exposed to traffic wear, it is at a fraction of the level paint would see in the actual traffic lanes. Of course there are also the issues of traction and glare, and around here the contribution the black surface makes to keeping ice off of paved roads and parking lots during the majority of the year.
    So go for those white roofs if it turns your crank, but before we get to far into trying to make all the roads white maybe some of these climate modeling deep thinkers might want to consult with some less intellectually gifted highway engineers from a few state DOTs who’ve actually built and tried to maintain a few roads in their time.

  84. RE: stevengoddard: (July 19, 2010 at 1:22 pm) “I keep my roof white all winter. The white color keeps the house cold, raising the heating bills.”

    Maybe someone should try to develop a special smart durable liquid-crystal material that only goes reflective if the roof temperature rises above 25 degrees C. — Yes, such a material is most likely an expensive unobtainium.

  85. Don Shaw writes: “If most commercial construction is flat black roofs without an “attic” above then some benefits are possible.”

    Here is july 2010 experience from Canada:

    I do not think cool roofs will end global warming… LOL
    But we all know how inside a black car in summer is torture.

    The cool roof effect is very real for houses with a flat roof and no attic such as most modernist homes, post and beam style, with skylights and miles of floor to ceiling glass windows. I can attest about it, on a commercial grade, high end building less than 10y old. Usually in summer, despite heat recovery/air recycling technology and of course AC connected to our swimming pool, the rooms were always managing to get stuffy after a while and we could feel heat radiating during the night, despite flat roof passive ventilation. Worse, when the tar roof membrane starts to loose its little white stones, the black tar appeared and it made the problem worse as only about 45inches separates the rooftop from the ceiling. We felt as if in a greenhouse… AC was working all the time even at night to keep at 26C, losing the battle and warming up our swimming pool so much that in the end, the house felt uncomfortable and the pool was way too hot unless you wanted hard boiled eggs…

    So out of curiosity I decided to try and I used a RV roof coating product from WhiteKnight called Flexcoat acrylic product, in 5 gallons cans, covering about 3,500 sqft roof with 10 of them. One coat is enough: you just pour the stuff on the roof and cover with a roll. I first tried above our bedroom. The change was immediately noticeable. No more stuffyness, the room stayed cool during the day and at night. On the roof, to the touch, the coated areas were cool even in the noon sun while an adjacent untreated area would be boiling hot.

    I covered the entire roof since the anticyclone kept being replenished by MPHs for days and the result is really fantastic: AC is running only when the sun set over our miles of glass sliding doors and only few times during the day to maintain a cool 22C while the pool temperature has remained comfortable. Considering it took me 3 days, 8 hours and $1,300, I can recommend it to anyone in our situation.

  86. Some 7 years ago, I had my house re-roofed, mainly because the concrete tiles were disintegrating. (The house was built in 1967/1968)

    I chose “corrugated iron” as the new material, being lighter and stronger, as well as providing additional protection against burglars. As I’ve done a little work Engineering HVAC systems, I chose a green “eucalyptus” colour for the roof, which imitates to some extent the optical properties of nature. Not that I’m anticipating photosynthesis. :-) It reflects “excess” light without being painful to look at from the street; as would be white or “natural” galvanized steel. (If I were in a mean mood, I’d get on the roof and paint disruptive patterns to frustrate aerial surveys by local government. :-))

    Instead of using minimum sarking (an aluminised foil) underneath the steel — a measure to reduce condensation on the underside — I chose instead an insulated (rock-wool) blanket with foil backing to be sandwiched between the steel and the battens. Not only does that provide substantial thermal insulation, it also makes the steel roof more quiet than the original tile roof in heavy rain.

    As for the lab results in the article; nice to see somebody trying to do some real research about how much direct influence we have on regional climate and how we can manipulate that impact. Even if the conclusions have been “obvious” for centuries.

  87. Believe me. On a personal application level this makes a huge difference. Been there done that. 7th grade science.

  88. It’s a nice idea but didn’t anyone think to find out what percentage of the U.S. is covered with buildings or roads? I think it is well below 10%.

  89. It’s a *** WIN – WIN *** situation.

    On April 1st everyone paints their roofs WHITE, then on November 1st they paint them BLACK.

    Voila — think of all the employment, and with the government covering the costs in income tax credits everyone wins. More employment, cooler/warmer houses, what more could Al Gore ask for?

  90. Jason Bair says:
    July 19, 2010 at 1:15 pm

    The difference in temp shouldn’t be surprising to anyone. Its much easier to walk barefoot on concrete than black asphalt. Concrete still heats up and contributes to UHI, but not as much as blacktop/black roofs.
    ——————————————–
    White sand isn’t too cool to bare feet…

  91. Any government program designed to “save” money will inevitably cost more than it avoids…

  92. I’m not sure this is a worthwhile approach but an even better “paint job” would be to use a paint who’s emissivity is high for long (IR) wavelength and low for short (VIS). Stuff like that does exist and I’ve played with it 25 year ago at the university. A roof like that would cool the house passively (though not much) but in comparison with a standard roof, it would make a great difference.

  93. Got it: paint the Oil Sands white and the greens and Obama’s eco-minions will love Alberta!

  94. How much did they pay scientists to learn that a black square heats up more in the sun than a white one?

    This is a no-brainer. Of course having a city full of white roofs and white roads and pavements will be cooler than black ones.

    What I would not like though is white roads or pavements. When driving along with a bright, but low sun, especially if it had been raining, then a white floor would be literally blinding. That would create very dangerous driving conditions.

  95. Just have reversible roof tiles. Black on one side (for winter) and white on the other (for summer)

  96. Roof colour is just an aspect of Passive Solar building design principals that have been around for years. There are plenty of books, papers, research, local government advice sheets, ‘proper models’, etc on this subject – they could have saved a packet and just searched the Internet for it…

    Or they could phoned the Australian government and asked for their handbook on it..

    Basically the main driver in end efficiency is the sarking under the roof itself, then the level of insulation present in the roof immediately above the ceiling and how well that ‘rejects’ heat transfer up or down; with some ventilation. Basically in Summer you don’t want the heat coming down and in Winter you don’t want your heat going up.. You can also do things like play around the shading available and how the visible ‘height’ of the Sun is lower in Winter than Summer (location permitting).

    Its quite effective when you get it right.

  97. What does this mean for the folkes who want to line their roofs with black solar cells. I guess solar panels must warm the earth.

  98. “OK you clever people,why are house radiators always white?”

    Because it looks nice.

    Since all heat from the heating system will be lost to the room somehow, it makes little difference what colour the radiator is.

    And anyways, you’re talking about white as visible wavelengths, and my radiators tend to run way cooler than that.

    On another topic, does anyone else get depressed at the number of comments from folk who ask why the reflected sunlight doesn’t heat the air as well? Even here on WUWT there is evidently very little understanding of fairly simple physics.

  99. Keith says:
    July 20, 2010 at 12:43 am
    Yes, you are absolutely correct re insulation and venting for private homes. The scientists would have only needed to look at house construction in New Jersey. And that’s why I added venting and attic insulation to my 40 year house a long time ago.
    Based on the press release, I suspect they were hung up on Chu’s earlier comments on painting roofs and roadways and got a stimulus for the computer study. I hope I am wrong but I suspect that they, like Chu, lack the common sense to find out how things are actually designed and constructed and that there are other means applied to reduce energy usage. A computer model is so much better and more impressive even if it does not model the real world.

  100. Viscount Monckton of Brenchley has already done some ‘back of a fag packet’ calculations on this and concluded the idea is rubbish.

    Extract from ‘‘Global warming’, painting your roof white, and the Chattanooga Chu-Chu’

    “About 75% of the Earth is covered in water or ice. Not even the Chu-Chu can paint
    water, though he probably thinks that with enough taxpayer subsidy he can walk on it.

    And there’s no need to paint ice because it’s white already. That leaves 25% of the
    surface.

    Let’s cautiously assume that 2% of the land is covered in roads or buildings with roofs:
    2% of 25% is 0.5% of the Earth’s surface. That’s how much of it we have to paint.
    About 40% of the atmosphere is covered in clouds. They’re white too, so they already
    reflect a lot of those glamor-puss photons right back into space where they came from.

    Then we have to allow for the fact that most buildings and roads are not in the tropics,
    where most of the sunlight comes in. We also have to allow for the fact that white paint is not a perfect reflector. And up to 30% of the land surface of the Earth is covered in snow for up to six months of the year. These factors bring us down to the equivalent of just 0.2% of the “global warming” at the Earth’s surface. Maybe.

    Then we have to divide that by 2, because half of the incoming radiation from the Sun is long-wave already, and – however much white paint we throw around – it gets all up close and personal with those hunky heteroatomic molecules on the way in from space.

    So, if we paint every road and every roof whiter than white, we’ll reduce “global
    warming” by 0.1%. That’s all.

    How much warming, in Fahrenheit degrees, will we prevent with the Chu-Chu’s cunning plan? Let’s pretend that the UN’s climate panel is right in assuming that “global warming” caused by humans is going to warm the world by 7 Fahrenheit degrees this century. Actually, it will probably be more like 1 Fahrenheit degree, but let’s clamber aboard the Chu-Chu’s bandwagon even as the wheels are noisily falling off.

    Seven Fahrenheit it is, then. All that roof-painting will reduce that global warming by seven thousandths of a Fahrenheit degree. That’s 0.007 Fahrenheit degrees. Yup, that’s all. The world’s temperature monitoring stations won’t even be able to measure it.”

    He also estimates that at $4 a gallon for the paint it’s going to cost $17 trillion to paint all the roofs to reduce global temperature by an estimated 0.007 Fahrenheit degrees.

  101. Daniel H says:
    July 19, 2010 at 7:21 pm
    “We should also consider putting more humans on rooftops by encouraging more sunbathing.”

    Bad idea. Over time, the albedo of humans drops if exposed to sunlight.

  102. My word! Those ancient Greeks were soooooo smart! Can you imagine it, two thousand plus years later and we’re still learning things from them. Do you think they were on to warp drive, starship, enterprise technology? They must have been from another universe.

    PS: And one other thing, has anyone else observed that humans seem to be getting just a little dumber with each new generation?

  103. On a well-constructed building the roof colour will have little impact on the heating/cooling load of that building. If it does make a noticeable difference, you have too little insulation in the roof/ceiling structure. Where it does make a difference is on the background temperature, and thus the heating/cooling loads of the collection of all buildings in the urban area. In economics parlance, it’s a “public good”. The marginal benefit to each individual property owner of adjusting the albedo of his own property is unlikely to be significant. Retrofitting existing properties is probably not worth it (unless the roof needs to be replaced anyhow).

    Most white or light-coloured materials are quite efficient thermal radiators – white radiator paint is especially good – but reflective metal foils are not.

    For road surfaces pure white would be too glaring, but ordinary concrete would be a reasonable compromise. Light-coloured ashphalts are also available. They cost a bit more than the common black stuff, but you only need enough to cover the surface to a few millimetres depth.

    It would certainly make sense to increase urban albedos this way in hot climates, and decrease them in cold climates. In cities with excessively cold winters and excessively hot summers maximising the amount of greenery would make most sense (because that mitigates both extremes), though thermosensitive coatings and adaptive structures would be fun. It should be understood that the underlying purpose should be simply to make city life more comfortable and pleasant; in no case would it have any significant impact on global temperatures, because cities comprise only a tiny fraction (~0.1%) of the globe.

  104. I live in a temperate clime, owning a flat-roofed house. It did not take Chu to make me paint my ‘wagon’ white. I did it many years ago, basing my decision on the science that I studied during my years at school and university, and can say that it had a great effect on the temperature inside my house especially during the months of July/August. It needs maintaining of course, ’cause the trick (not CRU’s trick in hiding the decline but a real temperature decline) is in the pure whiteness and reflectance of the roof. I m sure that this has also impacted positively on my electricity (aircon) bill and am proud to having contributed to lessening carbon emmissions more than my friend Al Gore did and long before Mr. Gore founded his church of catastrophism and thermogeddon.

  105. “but just a roof of a cooler color, a scenario that is more plausible to implement.”
    This is a great statement. Using reasonable scenarios rather than pie-in-the-sky.

    Here in Florida it seems to be popular to take off the tile and concrete tile roofs and replace them with shingles, usually darker in cooler. The northerners don’t seem to like the roof maintenance. Then when their houses blow away in a hurricane they wonder why. Also, when they move into canal front neighborhoods they cut down all of the trees (pines, live oaks, cabbage palms, etc) and plant little spindly palms that die when it freezes. I could go on. Sorry, I’m whining.

  106. Paul Birch writes: “On a well-constructed building the roof colour will have little impact on the heating/cooling load of that building. If it does make a noticeable difference, you have too little insulation in the roof/ceiling structure.”

    Indeed but you forget climate change. And I am not of course talking about the AGW kind but simply the real one, natural one that has increased the contrast between seasons over the past 30 years through rising atmospheric pressures: colder, sunnier winters and their equivalent in summer. Thus architects have designed homes for a certain climate only to find their buildings performing in a different one. What was appropriately designed then shows some strain and requires a bit of managing.

  107. My complaint is why the Sec of Energy is talking about white roofs in the first place. Why isn’t he talking about the newest innovations in nuclear-plant design that improves vastly on safety, fuel availability (breeds its own fuel) & virtually eliminates radioactive by-products?

    Oh wait. The American gov no longer has the courage to research these energy sources. I guess it’s up to the French, Soviets, Chinese & Indians.

  108. TomRude says:
    July 20, 2010 at 8:25 am
    Indeed but you forget climate change. And I am not of course talking about the AGW kind but simply the real one, natural one that has increased the contrast between seasons over the past 30 years through rising atmospheric pressures: colder, sunnier winters and their equivalent in summer. Thus architects have designed homes for a certain climate only to find their buildings performing in a different one. What was appropriately designed then shows some strain and requires a bit of managing.
    ________________________________________________________________________

    Certainly, architectural design needs to be appropriate for its climate. However, nowhere has climate changed enough to make previously appropriate designs inappropriate. (I don’t know what you mean by “rising atmospheric pressures”; so far as I’m aware there is no evidence of any significant change in atmospheric pressure over historical times).

    Whatever the climate, insulation is good. True, it’s more important in more severe climates (eg Arctic or Sahara Desert), but unless you live in a perpetually balmy island paradise, more insulation is still useful and cost effective.

  109. “Today, U.S. Energy Secretary Steven Chu announced a series of initiatives at the Department of Energy to more broadly implement cool roof technologies on DOE facilities and buildings across the federal government.”

    This is the glorious productivity of the green econonmy, as promised–the government coloring its roofs, with policy announcements of great solemnity.

  110. Ah. The creation ex nihilo powers of the Federal Gov’t:

    Behold:
    changing its roof colors,
    making solemn policy announcements, and
    giving us a glorious green economy based on nonproduction

    which “saves the taxpayers money!”

  111. Paul Birch please read Leroux “Dynamic Analysis of Weather and Climate”, 2010 Second edition, Springer.

  112. I am about to have to see to the roofing needs (water-shedding) of the house I own (Phoenix, AZ), and after a good deal of study, have decided to give new white elastomeric roof coating a try. It is relatively quite inexpensive, in the range of 20 cents per sq ft, 2 coats, for materials, can be easily applied with brush, roller or brush over existing asphalt shingles, and is adequately attractive.

    Cheap enough to try. I have grandsons who are more than willing enough to provide the labor.

  113. Flat white roof around the Mediterranean; fine. No good to me though. Nothing to do with heat. If you live where you can expect six or seven inches of rain in two hours once every couple of years and three inches in an hour any summer, you are not going to be able to persuade your loving spouse that the flat roof was one of your better ideas.

  114. Reducing urban heat is a desirable. I can buy the white roof idea on that basis, but I can’t buy that white roofing et al can have a global effect. Man’s constructions probably cover less than .001% of the Earth’s surface. We’re supposed to believe that coloring this miniscule percentage of the Earth’s surface area white is supposed to impact global climate?

  115. TomRude says:
    July 20, 2010 at 11:33 am
    Paul Birch please read Leroux “Dynamic Analysis of Weather and Climate”, 2010 Second edition, Springer.
    _________________________________________________________________

    Why? What do you claim it says that would conflict with what I said above (most of which is pretty obvious)?

  116. “Equivalent to Getting 300 Millions Cars Off the Road”

    The science behind this statement looks really sound. If we offset the heating effect of the emission of roughly 24 Gt of CO2, just by guilding the roof, I think bulldozing the buildings down entirely would certainly get us more than an equivalent annual rate of 1.2 Gt per year.

  117. It is gratifying that Environmental Research Letters has taken les than a decade to catch up with the August 21 2000 issue of Forbes magazine:

    http://www.forbes.com/forbes/2000/0821/6605036a.html

    Forbes 21 August 2000
    Paint the town white
    by Russell Seitz
    Olin Institiute for Strategic Studies ,Harvard University

    Al Gore’s answer to global warming is raising fossil fuel taxes. This may be as irrelevant as it is expensive and intrusive. For the greenhouse effect is not driven by fossil fuel burning, but by the power of the sun. Which is why, when a greenhouse gets too steamy, you whitewash it. This simple, passive solar cooling works so well, regardless of size, that it even applies to that largest of greenhouses, the Earth itself.

    The real problem is Earth’s low albedo–it reflects only a small fraction of the sun’s energy because most of its surface is dark compared to a snowfield or a coat of white paint. Such white surfaces reflect three times as much as bare rock or desert soil, and up to ten times as much as deep water or black asphalt paving.

    It is easy to calculate how much it would take to counter the retention of heat by greenhouse gases in the atmosphere. A large amount of radiant energy streams in from the sun; a small quantity of the same is trapped by carbon dioxide. The trapping effect comes to 1.62 watts per square meter of the planet’s surface, of which some 300 to 400 milliwatts is due to past fossil fuel burning. That 350 milliwatts is still only a thousandth of the incoming solar energy. Which is why enhancing the reflectivity of a corresponding fraction of the earth’s surface to the brightness of a snowfield would reverse the cumulative environmental impact of the industrial revolution. A thousandth of the earth’s surface comes to 200,000 square miles. Let’s do a little more–250,000 square miles–to allow for the fact that a white surface on the ground is not a perfect mirror into outer space.

    Split 6 billion ways, brightening up 250,000 square miles is not such a formidable task: It comes to about 1,000 square feet apiece. Apart from that one-time obligation, we’d have to continue with a small annual dose of brightening to counteract the new damage from today’s fossil fuel burning. This annual obligation would be on the order of a few percent of the one-time cost.

    There is plenty of space to install this cheap and passive insurance against climatic bracket creep: Even at a rate of 5,000 square miles a year, it would take centuries to exhaust the supply of treeless badlands. Compared to the draconian economics of global carbon taxation, whitewashing might be something of a bargain.

    The greatest benefits would arise from whitening or brightening dark unvegetated landscapes in sunny climates, in effect providing “snow” that would not disappear from rocky uplands with the coming of summer. The bright surface need not be artificial–introducing and propagating any of many species of bright-leafed vegetation, natural or genetically engineered, can have the same effect.

    Or we could lighten up the hundreds of thousands of square miles of roofs and roadways that already exist, starting with those expanses of asphalt that already contribute to cities being warmer than the countryside. Titanium dioxide is the best pigment for producing this “White House Effect”: enduring, utterly nontoxic and dirt cheap–one penny’s worth will cover a square foot nicely. China clay, or kaolin, is less efficient as a reflector, but an order of magnitude cheaper. Applying a paint film of either can suffice to raise the reflectiveness of most natural surfaces from 25% or less to 75% or more, at a materials cost on the order of around $250,000 per square mile. America’s annual per capita share of such a global solution would cost as much as a couple of gallons of gas.

    Once you understand that the sun power entering our atmosphere is nearly 100,000 times the power of the whole human energy economy, you can comprehend how, at one and the same time, carbon taxation would be both a fiscal enormity and an environmental irrelevance. After two generations of solar-cell R&D it still costs $3 million a megawatt to convert sunlight into electrical power. But $300 worth of aluminum foil will reflect a megawatt of solar energy back into space.

    It will grieve the green and frugal alike to learn that some things are cheaper than energy conservation. Just saying no to the passive solar heating of the Earth is one of them.

    (Edited by Tim W. Ferguson, now Editor In Chief of Forbes )

  118. The use of light colored surfaces in hotter climates is nothing new and not rocket science. In Florida, virtually all cars delivered to dealer lots are painted with light colors and have interiors of light colored fabrics. Anyone who buys a black car in Florida or similar warm State deserves the thrill of jumping into a microwave oven.

  119. Charles S. Opalek, PE says:
    July 20, 2010 at 6:58 pm

    The use of light colored surfaces in hotter climates is nothing new and not rocket science. In Florida, virtually all cars delivered to dealer lots are painted with light colors and have interiors of light colored fabrics. Anyone who buys a black car in Florida or similar warm State deserves the thrill of jumping into a microwave oven.
    ______________________________
    Tell me about it.

    My pickup is black and the A/C quit a couple of years ago. At least NC is not as hot as SC so I do not burn my hands on the steering wheel if I am not wearing gloves.

    I am planning on painting the roof white. At 18 yrs old I do not care what it looks like any more.

  120. Paul Birch wrote: “Why? What do you claim it says that would conflict with what I said above (most of which is pretty obvious)?”

    Here is what you said.

    “(I don’t know what you mean by “rising atmospheric pressures”; so far as I’m aware there is no evidence of any significant change in atmospheric pressure over historical times).”

    I am simply encouraging you to read and learn from a climatologist who knows and explains. It’s worthy of your time.

  121. TomRude says:
    July 21, 2010 at 12:07 am
    Paul Birch wrote: “(I don’t know what you mean by “rising atmospheric pressures”; so far as I’m aware there is no evidence of any significant change in atmospheric pressure over historical times).”

    I am simply encouraging you to read and learn from a climatologist who knows and explains. It’s worthy of your time.
    _________________________________________________________________________

    What a snarky remark. If this alleged climatologist claims that atmospheric pressure has been changing significantly over the past thirty years, as you imply, then I’d say either he knows something vital that no one else does or he knows squat. My money’s on the latter. It is physically impossible for global atmospheric pressure to change significantly unless there are major net sources or sinks of nitrogen or oxygen. Fossil fuel burning is roughly neutral until the CO2 is sequestered, but would in any case be equivalent to a change in altitude <10cm a year (bear in mind that pressure fluctuations due to weather fronts can be up to the equivalent of ~500m in altitude). A warmer climate could put more water vapour into the air, but this would only amount to the equivalent of ~1-2 m of altitude per centigrade degree (depending on assumptions of average relative humidity, lapse rate, distribution of temperature globally, etc.). This is quite insignificant. There would be no impact on architectural designs unless the change were enormously greater, say equivalent to ~1km. Furthermore, although increasing altitude normally reduces temperatures in line with the adiabatic lapse rates, this would not occur with a global reduction in atmospheric pressure; the base temperature would barely change.

  122. From some posts here, I’m getting the impression that we have to be careful in how much we paint the planet white, ’cause the albedo effect will be so great the planet may freeze. But the cientific truth lies elswhere. Our effect on the planet is irrelevant, and one would easily reach this conclusion when one considers what could have caused such a fast freezing, and re-heating of the planet during the most recent (in geological history) event, that is, the Younger Dryas Period.

    Painting one’s wagon white is highly effective, but it stops there.

  123. Paul Linsay says:
    July 19, 2010 at 1:22 pm
    “This has been done on the Mediterranean since forever and for the same reason.”

    Are you 100% sure? I thought that whitewash was used because you could see when it needed replacing to reduce structural crumbling. After all, what else of convenience was there to paint onto the buildings in the early days?

  124. Russell Seitz says:
    July 20, 2010 at 3:30 pm
    Use titanium dioxide, the whitest white.

    Sorry, Russell, there just ain’t nearly enough TiO2 to go round economically. It also takes enormous energy to strip out the last bits of omnipresent iron, which cause it to go brown in the weather.

  125. That’s an interesting cartoon with the arrows in the lead story. Especially the un-named yellow arrow to the right, which suddenly gets bigger. What if it shines onto a taller adjacent building? What if it gets sucked down an air conditioner inlet and requires more fuel to make the air conditioner achieve low temperature?

    Remember, the incoming sunlight does not know the colour of the roof. It’s the unstated wavelength band of that yellow arrow that is missing from the cartoon. What is it?

  126. Geoff Sherrington says:
    “… what else of convenience was there to paint onto the buildings in the early days?”
    Ochre. Mud. Cement. Dung. Sand (with a binder, eg dung). They’ve all been used. Whitewash is probably the most convenient, though.

    “Sorry, Russell, there just ain’t nearly enough TiO2 to go round economically. It also takes enormous energy to strip out the last bits of omnipresent iron, which cause it to go brown in the weather.”

    There’s more than enough titanium to paint a sphere the size of Earth’s orbit. The energy required to make the TiO2 is a minuscule fraction of the reduction in energy absorbed to the environment over the paint’s life; at a very rough estimate, payback time ~1000s (~100MJ/kgTi, 1gTi/m2, 100W/m2 less sunlight absorbed).

    ” It’s the unstated wavelength band of that yellow arrow that is missing from the cartoon. What is it?”

    It’s sunlight! It’s the light reflected back into space by the white surface that would otherwise have been absorbed by the black surface.

  127. Paul Birch writes: “What a snarky remark. If this alleged climatologist claims that atmospheric pressure has been changing significantly over the past thirty years, as you imply, then I’d say either he knows something vital that no one else does or he knows squat…”

    Listen Birch, that was no snarky remark.
    From Wiki:

    “Leroux demonstrated through the analysis of synoptic maps, satellite imagery, meteorological and palaeoenvironmental data over Tropical Africa that the seasonal and palaeoclimatic migration of the Meteorological Equator represents a reliable proxy of the Earth’s climate evolution [Leroux M. (1983). PhD. Thesis : Le climat de l'Afrique tropicale. Ed. H. Champion/M. Slatkine, Paris/Genève, t.1. : 636 p., 349 fig., t. 2 : notice et atlas de 250 cartes], ["The Meteorology and Climate of Tropical Africa", Springer Verlag, Springer-Praxis books in Environmental Sciences, London, NY, 548 pp + CD: 300 pp, 250 charts, 2001, ISBN: 978-3-540-42636-3].

    This migration and the extent of the Meteorological Equator are the consequence of continuous meridional exchanges in the denser, lower layers of the atmosphere, which circulation is governed by the incessant ballet of the Mobile Polar Highs or Anticyclone Mobile Polaire, 1.5km high, 3,000 km diameter discoid, lenticular cold air-masses anticyclones originating from the poles, whose strength and frequency depends directly on the thermal polar deficit. Cooling spurns an accelerated circulation while warming will slow the general circulation and exchanges [“The Mobile Polar High: a new concept explaining present mechanisms of meridional air-mass and energy exchanges and global propagation of palaeoclimatic changes” Marcel Leroux, Global and Planetary Change, 7 (1993) 69-93 Elsevier Science Publishers B V, Amsterdam].

    The aerological spaces of circulation, zones of continuous circulation from the pole to the equator are bound by relief over 2,000m and the present position of continents. In light of direct observations [Leroux M. (1983). PhD. Thesis : Le climat de l'Afrique tropicale. Ed. H. Champion/M. Slatkine, Paris/Genève, t.1. : 636 p., 349 fig., t. 2 : notice et atlas de 250 cartes.], [“Dynamic Analysis of Weather and Climate Atmospheric Circulation, Perturbations, Climatic Evolution”, Springer-Praxis books in Environmental Sciences, 2nd ed., 2010, 440p., ISBN: 978-3-642-04679-7 ], Leroux’s reconstruction exposes the inconsistencies of previous general circulation models, of oscillation indexes and of frontological, dynamical, reductionist and diagnostic schools of Meteorology. This made him a controversial figure.

    In doing so, Leroux refutes the artificial separation between Meteorology and Climatology and through the MPH concept, redefines both disciplines in a similar way Plate Tectonics revolutionized Earth Sciences in the 1960s. He reconstructed the geometry of the troposphere general circulation [“The Mobile Polar High: a new concept explaining present mechanisms of meridional air-mass and energy exchanges and global propagation of palaeoclimatic changes” Marcel Leroux, Global and Planetary Change, 7 (1993) 69-93 Elsevier Science Publishers B V, Amsterdam] and demonstrated that very little is owed to hazard or chaos: there is no ‘unruly climate’ but intensity shifts of the sum of weather processes that constitute the climate.

    This research confirmed that the climatic shift observed since the 1970s corresponds to the setting of an accelerated mode of circulation, always associated with cooling during the late Quaternary palaeoclimatic evolution, and its meteorological consequences: contrasted weather, stronger mid-latitude storms, increase water vapour in the troposphere and impermanent anticyclonic stability over continents leading to vigorous cold snaps in winter and heatwaves in summer [“Dynamic Analysis of Weather and Climate Atmospheric Circulation, Perturbations, Climatic Evolution”, Springer-Praxis books in Environmental Sciences, 2nd ed., 2010, 440p., ISBN: 978-3-642-04679-7].

    In consequence, his results refute the validity of a Global Mean Temperature curve as a major climatic proxy and contradict the assumption that weather changes observed in the second half of the XX Century were the consequence of an Anthropogenic Global Warming climatic change brought by the release of greenhouse gases due to industrial and human activities ["Global Warming: Myth or Reality? The Erring Ways of Climatology", Springer-Praxis books in Environmental Sciences, Berlin, Heidelberg, London, New- York, 509p., 2005, ISBN: 978-3-540-23909-3].

    Furthermore, his work provides the meteorological mechanism for past glaciations and de-glaciations, improves meteorological prediction models and climate simulation accuracy in constraining them through the real geometry of atmospheric circulation, its discontinuities, energy exchanges and their associated clouds ["Dynamic Analysis of Weather and Climate", J. Wiley ed. Praxis-Wiley series in Atmospheric Physics, London, NY, 365 pp, 1998].

    In his approach, Leroux was a true disciple of Descartes and his books are highly didactic. The English 2nd edition of “Dynamic Analysis of Weather and Climate, Atmospheric Circulation, Perturbations, Climatic Evolution” was completed in 2008 two months before his passing and published in January 2010 [“Dynamic Analysis of Weather and Climate Atmospheric Circulation, Perturbations, Climatic Evolution”, Springer-Praxis books in Environmental Sciences, 2nd ed., 2010, 440p., ISBN: 978-3-642-04679-7].”

    So Birch had you simply bothered to search you’d have found that my comment related to the increasing strength of anticyclones -rapid mode of circulation-, pushing towards the ME in both hemispheres and on the path of which over time mean atmospheric pressure have been measured rising for the past 40 years. Correlatively associated depressions have been deepening.

    Before disparaging you could have also asked me to clarify the context of my comment.
    EOM.

  128. TomRude says:
    July 21, 2010 at 8:34 am
    “Listen Birch, that was no snarky remark. … Before disparaging you could have also asked me to clarify the context of my comment.”

    I did. Your snarky remark was in response to my request for clarification.

    Pasting a big chunk from wiki is not scientific argument, especially since it didn’t even mention the atmospheric pressure that you claim has risen enough over thirty years to make previously appropriate architectural design no longer appropriate. Which is plain daft – do you think architects change their house designs just because they’ve gone a few yards along the road to where it’s a foot higher? Buildings have to cope with the wide extremes of weather. A small shift in the bias or average or frequency of that weather within its normal fluctuations has essentially no impact on the design. Even a big shift may not matter much; a house from Northern Scandinavia will probably do just fine in Southern California.

    Theoretically, a marginal shift in eg average temperature could make a marginal shift in economically optimum insulation levels, etc., but in practise architects simply don’t work to such tiny tolerances (and almost all buildings could benefit from more insulation anyway). Other factors, such as solar gain, depend on the building’s latitude, which doesn’t change (or only very very slightly, with nutation, continental drift, etc.).

  129. Birch writes: “Pasting a big chunk from wiki is not scientific argument, especially since it didn’t even mention the atmospheric pressure that you claim has risen enough over thirty years to make previously appropriate architectural design no longer appropriate…”

    Really, your knowledge about atmospheric circulation and its affect on weather leaves much to be desired. I never said that it was the rise in pressure that made house designs obsolete but the rise of pressure that accompanied an evolution of weather over an region, bringing anticyclone permanence, and thus would be reflected by heatwaves in summer and cold waves in winter, i.e. more extreme weather more often. Thus a building designed for a more temperate climate would be strained in a more continental climate. This quite different than your “Which is plain daft – do you think architects change their house designs just because they’ve gone a few yards along the road to where it’s a foot higher?”

    And I do not claim, it has been MEASURED (CDC/NCEP-NCAR data). Unless of course you have nothing to learn from anyone… and That is a snarky final remark.

  130. TomRude:

    You certainly did claim that increasing atmospheric pressure had made achitectural designs obsolete. You said, “…
    that has increased the contrast between seasons over the past 30 years through rising atmospheric pressures…” (my emphasis).

    Slight changes in atmospheric pressure cannot significantly “increase the contrast between seasons”. It is physically nonsensical. We are talking about variations at the 0.01% (0.1mbar) level, which, if they related directly to seasonal temperature differences would affect the seasonal peaks by only ~0.001 degree! Negligible. Moreover, to the extent that there is any effect at all, the sign is the opposite to that which you claim: in planetary science thicker atmospheres mean less seasonal variation, not more. Slight changes in atmospheric pressure are the (insignificant) consequence of changes in climate, not the cause.

    In any case, whatever the causes, climate simply hasn’t changed very much in the past thirty years – not remotely enough to make previously suitable building designs obsolete. I don’t need fancy measurements to tell me that (though they confirm it very strongly). Just looking at the buildings and remembering is enough.

  131. Looking at the literature on black body radiation, it seems to to me to be scientifically agreed that in a black painted box, the black painted exterior surface absorbs heat and simultaneously radiates heat to the inside of the box, so the box gets warmer.
    It also appears that the study of white body radiation is not nearly as sexy as black, (why, I have no idea) with the result that not much appears to be written up on it.
    OK.
    So my black painted bungalows in Panama scientifically absorbed solar heat which scientifically made the rooms warmer, whether other commenters agree or not.
    As no scientific work has been done on white body radiation, we can only assume that white body radiation doesn’t, at the moment exist, that is, it cannot be scientifically proven.
    In this case we do not really know whether the bungalow rooms in Panama got cooler or didn’t, sort of Schrodinger rooms.
    Or white magic perhaps.
    Anyway, we got cooler rooms.
    Funny, that.

  132. Paul Birch writes: “We are talking about variations at the 0.01% (0.1mbar) level,…”

    OK you know better.

    CDC/NCEP-NCAR data, evolution of mean annual surface pressure, period 1948-2002:
    Vigouroux 2004, Lake Constance from 1015 to 1019mb
    Pommier 2004, mediterranean basin, Cairo, Ghadames from 1013 to 1016mb
    Pommier 2002 central France from 1015 to 1017mb
    LCRE Dakar, from 1011 to 1012.5mb
    Barbier 2004 Panama from 1009 to 1011.5mb
    Gobi desert China, from 1014 to 1019mb

    Zones of associated depressions trajectories show deepening of these depressions over the same period. The frequency of these is increasing too.

    0.1mb… yeah right!

  133. From the article:
    “Cool roofs are one of the quickest and lowest cost ways we can reduce our global carbon emissions and begin the hard work of slowing climate change,” said Chu.

    DO TELL: If all of the electrical energy used to either heat or cool a building is derived from either water or nuclear power, then how in the name of all that good and proper, will a white roof reduce the carbon in the atmosphere?

    That is right on par with painting the Andes white …

    Next, I’ll presume that GISS, et al., will commence to say that parking the temperature measurement instruments is quite okay on white roofs, right?

    Well, let me ask: Has anyone ever done the science to determine the actual difference between the temperatures experienced on white vs black roofs vs a properly located Stevenson Screen?

    This whole scheme is one of deflection away from the central core of an extremely faulted premise: Human-caused GW.

    They can’t prove their assertion, so instead of admitting having wasted literally BILLIONS of dollars pushing a lie, they now engage in taking advantage of the very crisis which they themselves created: Never let a good crisis go to waste!

    The team who did the ‘Hide the Decline’ video, now now needs to do a sequel: ‘Pushing a Lie.’

  134. TomRude says:
    July 21, 2010 at 6:46 pm
    Paul Birch writes: “We are talking about variations at the 0.01% (0.1mbar) level,…”
    OK you know better.
    _________________________
    I know on hard physical grounds (conservation of mass!) that the secular change in atmospheric pressure cannot be more than that order of magnitude. If alleged measurements purport to show otherwise, they are wrong. I suspect that you simply don’t understand what is being measured or described. At any place, local atmospheric pressure swings wildly – by up to ~50mbar – due to weather. Because of this, if you try to measure the mean atmospheric pressure there, it will be highly uncertain. The statistics are messy, because the distribution is long-tailed, but for a maritime climate outside the tropics, one might expect to get within a few mbar over one year. Over thirty years one could gain another factor of two or three. Elsewhere, the accuracy will be even less, because with longer-lived or fewer weather patterns there are fewer independent datapoints. The error bars are far larger than any real secular variation. Only by combining a large number of simultaneous readings across the globe, within and without each weather pattern (cyclonic or anticyclonic), could one improve the accuracy enough to see the changes due to more/less water vapour, release/absorption of CO2 etc. “Standard atmospheric pressure” is defined as 101325N/m2, but I doubt whether the global measurement accuracy really justifies the last few places.

  135. Paul Birch says:
    July 21, 2010 at 7:06 am
    Plenty of TiO2?

    At one stage our parent company owned a part of subsidiary named Rutile and Zircon Mines, near Tomago, Australia. It was a world scale producer. Rutile is like TiO2 with a lot of natural iron in it. It is the removal of the iron that takes huge energy. I managed a large pilot plant one year that tried just that. The next hurdle is to get permission to mine for rutile or anastase or whatever the mineral form might be, for much of it is in beach sands and we don’t want to mine them any more, do we? We’d chortle with joy if rising oceans reduced their economic value to nil.

    Why do people like you get masochistic delight from gloomy predictions?

    Finally, I’m not going to indulge in discussion about meaningless calculations about paint areas, when I stressed that “economically” there is not enough TiO2 to go round. And you did not address my point about where the reflected heat went, maybe onto the building next door, maybe down an adjacent air conditioner inlet. Maybe some even goes up into the sky and returns after bouncing off clouds. So what wavelength band do you imagine the yellow arrow light covers, in common units like microns? Or do you not know? It’s a fairly important question in the balance of energy.

    Try the KISS principle instead of making up numbers.

  136. OK Paul Birch, we must be talking about two different things: I am talking about weather related atmospheric pressure trends because in the end this is what’s we are here interested in since climate is the sum of weathers (how many times did I mention that associated depressions were deeper?). You, on the other hand, must be talking about a global atmospheric pressure.
    In any case, my suggestion to read “dynamic analysis of weather and climate” was genuine and not snarky. EOM

  137. Geoff Sherrington says:
    July 22, 2010 at 6:18 am
    Paul Birch says:
    July 21, 2010 at 7:06 am
    Plenty of TiO2?

    “It is the removal of the iron that takes huge energy.”
    Only huge relative to the 19MJ/kgTi enthalpy for the reduction of TiO2 to Ti. Even thirty years ago, a figure of ~800MJ/kgTi was typical. There were many inefficiencies in that process, so I have little doubt that my figure of 100MJ/kgTi would be achievable for large-scale production. NASA SP-428 considers a variety of production processes for the space manufacturing facility utilising lunar ilmenite concentrate with 48%TiO2, 43%FeO, from bulk mare soil, which despite being far inferior as an ore to rutile would permit the extraction of a nominal 20,000 tons a year at an energy cost well under 100MJ/Ti, with co-production of a similar quantity of iron. Recycling the sensible heat in the reaction products would improve on this further.

    “Why do people like you get masochistic delight from gloomy predictions?”
    !!! You’re the one making gloomy predictions – that there wouldn’t be enough white paint! I’m saying that, on the contrary, there is ample energy and more than ample raw materials. If demand for TiO2 increases, then, over the medium and long term as new plants come into operation, the real cost will fall.

    “And you did not address my point about where the reflected heat went”
    Yes, I did. It goes back into space! That’s what albedo means – the fraction reflected back into space. The fact that not quite all of the reflected light makes it back out is part of the reason for the conservative figure they used for the increase in albedo. And it’s not reflected heat. It’s reflected sunlight.

    “So what wavelength band do you imagine the yellow arrow light covers, in common units like microns? Or do you not know? It’s a fairly important question in the balance of energy. Try the KISS principle instead of making up numbers.”

    It’s sunlight! I don’t know how to put it any simpler than that. Black body radiation at a temperature ~6000K, most of the energy lying between ~0.2 micron and ~1 micron, with the peak in the yellow around half a micron. Thermal radiation at ~300K is of much longer wavelength ~10 micron; at those wavelengths radiator paint and TiO2 are nearly black.

  138. TomRude says:
    July 22, 2010 at 8:39 am
    OK Paul Birch, we must be talking about two different things: I am talking about weather related atmospheric pressure trends because in the end this is what’s we are here interested in since climate is the sum of weathers (how many times did I mention that associated depressions were deeper?). You, on the other hand, must be talking about a global atmospheric pressure.
    In any case, my suggestion to read “dynamic analysis of weather and climate” was genuine and not snarky. EOM
    _________________________________________________________________

    OK. If you’re talking about local atmospheric pressures, not global, then for every locality with an increase in pressure there must be another with a corresponding reduction in pressure. They can’t all be on a rising trend. That would be rather like this winter, when everyone was cold but, magically, the global temperature was said to be hot! Even locally, one simply cannot obtain a significant measure of atmospheric pressure trend over thirty years; the statistical fluctuations are far too intractable; you can calculate an average trend line over the period if you like, but it doesn’t mean anything. Even if it did mean something, the figures you gave are still far too small to have any impact on building design (still less than 40m of equivalent altitude). Nor would it have any significant effect on the weather; within quite wide limits, the absolute atmospheric pressure doesn’t matter.

    If you simply mean that weather extremes have become more severe, then talk of atmospheric pressures is a red herring. Even there, I would not accept that weather has become more extreme over the past thirty years. You can always cherry-pick locations where it appears to have, but I have also seen studies showing less extreme weather. Again, the natural variability of weather – and the long-tailed nature of the frequency distributions – means that we just can’t distinguish such local apparent trends from pure chance.

    Moreover, to come back to the crucial point you seem to be ignoring, suppose that deeper depressions were more frequent; in these locations, buildings are already designed to cope with such depressions. They have to be, because they’re already a common enough feature of the climate. So buildings that had appropriate architectural designs before would still be appropriate; and ones that were inappropriate would still be inappropriate. There would have to be a quite drastic – and implausible – extension of the absolute weather extremes (in severity not just frequency) for there to be any real need to adapt building design to changing conditions. Certainly nothing of the sort has yet happened anywhere.

  139. “They can’t all be on a rising trend.” Indeed we agree.
    As for building designs that would be interchangeable from Sweden to Arizona, one truly wonders why we’d have different designs over centuries if one house could fit all.

    “If you simply mean that weather extremes have become more severe, then talk of atmospheric pressures is a red herring. Even there, I would not accept that weather has become more extreme over the past thirty years.”
    Based on what? Really you would benefit from reading the reference I invited you to explore before you go on over extending yourself on meteorology and climatology.

  140. TomRude says:
    July 22, 2010 at 1:10 pm
    “As for building designs that would be interchangeable from Sweden to Arizona, one truly wonders why we’d have different designs over centuries if one house could fit all.”

    You truly wonder over something so obvious? Technology changes. Society changes. Wealth changes. Fashions change. Laws change. Government policies change. Resources change. And personal preferences vary. That’s why houses aren’t all the same.
    Climate change doesn’t even make it onto the list.

    Do you seriously doubt that a well-made modern house from Northern Scandinavia would still work in the climate of Southern California (or Arizona, if you prefer)? There is actually a strong export market for Swedish “flat pack” houses across the developed world (including the southern US). As I keep trying to point out to you, the most important building design features are sturdy construction and good insulation – and those are appropriate in every climate. Taking into account solar gain, different designs may be optimal at different latitudes (though Roman Villas are much the same whether in the Med or up by Hadrian’s Wall), but this does not change with epoch; it is not subject to “climate change”.

    I said, “If you simply mean that weather extremes have become more severe, then talk of atmospheric pressures is a red herring. Even there, I would not accept that weather has become more extreme over the past thirty years.”
    You said, “Based on what?”
    I had already answered that in the next two sentences “You can always cherry-pick locations where it appears to have [become more severe], but I have also seen studies showing less extreme weather. Again, the natural variability of weather – and the long-tailed nature of the frequency distributions – means that we just can’t distinguish such local apparent trends from pure chance.” I could also have added, personal observation. You seem strangely unwilling to accept just how radically variable – and unpredictable – “normal” weather is.

  141. Do the fools presenting this idea as a solution ever THINK of the many of the same roofs in the hot summer (requires white roofs and white streets solution Chu is gibbering about) are in the SAME PLACE as areas that require black roofs and black streets to melt the winter snow and ice, keep the same buildings warmer in the winters?

    Temperatures vary – a lot. Summer temp’s across most of the physical US vary from low 100’s (F) to low 90’s. (If there WERE REALLY an economic advantage of painting a building’s roof white – then the OWNER should be the one doing it. For the owner’s benefit, the owner’s savings in cooling costs. That there is NO financial reason to do so tells me that Chu is wrong. Dead wrong. That, or the need for each owner to do something else (maybe fix something that really needs fixing, or paying somebody’s salary, or buying paper, or buying ink, or buying a congressman’s vote ) is more important tot hte INDIVIDUAL owner . In every case in the real world – painting the roof white fails the “will it pay off?” test.

    Across the same area, winter temps very from -15 (F) to +20 and +30 (F) – Winter heating (eased by black roofs) and winter snow removal (simplified by black streets melting tons of ice and small falls by mid-morning and the next day) allow most of the country to simply ignore snow days and snow storms. So, who is going to pay (and re-pay, and re-pay, and re-pay) for “painting the streets white” (and – er, celaning them again when tire black and tire residue make them gray again) ?)

    The “ideal” of “we’re going to solve this problem” (which doesn’t exist) by spending (wasting) millions of dollars that will cost money the next season seems to have completely skipped his ignobel-filled mind.

  142. Amazingly you need not to learn from anybody Paul Birch even when you clearly are out of your depth. You know it all: is the Nobel forthcoming or just “been there, done that”? Need not replying: we already figured out the answer. Bye.

  143. While it is remotely possible that someone may be able to develop an economical thermochromatic roofing material that might be black in cold weather and white or silver in hot weather, I think people would not be prepared to see the exterior walls of their homes or their roadways changing color this way.

    Example: Thermochromatic Mugs from QOOP

  144. TomRude says:
    July 22, 2010 at 7:25 pm
    Amazingly you need not to learn from anybody Paul Birch even when you clearly are out of your depth. You know it all: is the Nobel forthcoming or just “been there, done that”? Need not replying: we already figured out the answer. Bye.
    __________________________________________________________________

    Suppose you address the actual science and rational arguments instead of making absurd personal attacks and relying upon appeals to (nonexistent) authority.

  145. RACookPE1978 says:
    July 22, 2010 at 5:03 pm
    “Do the fools presenting this idea as a solution ever THINK of the many of the same roofs in the hot summer (requires white roofs and white streets solution Chu is gibbering about) are in the SAME PLACE as areas that require black roofs and black streets to melt the winter snow and ice, keep the same buildings warmer in the winters?”

    This topic has been discussed, on this and earlier threads. First, there are many places that would benefit from cooling in summer and do not have a snow problem in winter; still others where the heat of summer is a more serious problem than the snow in winter; still others where it’s the other way round and they would benefit more from warming. It’s not one size fits all. Places that would benefit from both cooling in summer and warming in winter can be improved by maximising the amount of greenery, which mitigates both extremes. Thermosensitive paint and adaptive roof structures have also been mooted.

    “If there WERE REALLY an economic advantage of painting a building’s roof white – then the OWNER should be the one doing it. For the owner’s benefit, the owner’s savings in cooling costs. That there is NO financial reason to do so tells me that Chu is wrong. ”
    Adjusting the albedo of a city is an example of a “public good”, in which the individual property owner captures only a small fraction of the benefit of his investment, but also benefits from the investments made by everyone else. Most of the economic benefit comes in the form of positive externalities.

    “… simplified by black streets melting tons of ice and small falls by mid-morning and the next day…”
    I wonder whether anyone has measured the benefit of dark roads on snow and ice removal? It’s not as straightforward as one might think. My experience in the UK suggests that the primary snow removal mechanism is the movement of traffic, churning it into slush and pushing it to the sides of the road. The colour of the road under the snow doesn’t make any difference until the road surface has been exposed, when the snow at the edges does melt faster over black tarmac. Roads with light tarmac and concrete do not seem to suffer from snow retention any more than the roads in black tarmac (for equivalent traffic volumes). Bear in mind that snow falls from leaden skies, when there’s no significant solar gain to black surfaces. I would also say that black tarmac seems somewhat more likely to suffer dangerous iceing, perhaps because snow or frost melts, then refreezes, or perhaps only because black tarmac surfaces tend to be smoother.

    “painting the streets white” (and – er, celaning them again when tire black and tire residue make them gray again) ? ”
    I don’t think anyone wants to paint the roads pure white. In the past few days I’ve made a note of the local road surfaces. A surprising percentage of the roads are in various light tarmacs. Not merely the pigmented asphalts used as top dressings at junctions, etc., and which have a slight cost premium, but also cheaper sorts in which the bitumen flows or is washed away from the top of the stones, leaving them proud of the surface and showing their natural colours. Any tire residue or skid marks also wash off. These light tarmacs are actually pleasanter to drive on (at modest urban speeds) than smooth black tarmac.

  146. One should keep in mind that a dark, high emissivity road surface is also more prone to radiative cooling at night in the winter, as those who may have had the misfortune to encounter ‘black ice’ at high speed may know only too well.

  147. So question to DOE policymakers:

    Will the DOE facilities in northern areas be allowed to substitute warm roofs (black, I suppose) in place of cool roofs? Off the top of my head:
    – Idaho National Energy Laboratory (INEL) near Idaho Falls, ID
    – Knolls Atomic Power Lab (KAPL) in Schenectady, NY
    I can’t imagine looking someone in the eye who works at either of those two and telling them they need to make a cooler roof. Aside from the personal anguish associated with giving this news, it would probably save more energy on heating than it necessitated in cooling.

    Sorry to any DOE-ites who also work and the frigid north. Those 2 were just the best 2 examples I could think of off the top of my head. I know it gets cold at Argonne, but that’s basically Chicago so it doesn’t count. :)

  148. “My experience in the UK suggests that the primary snow removal mechanism is the movement of traffic, churning it into slush and pushing it to the sides of the road. The colour of the road under the snow doesn’t make any difference until the road surface has been exposed, when the snow at the edges does melt faster over black tarmac. Roads with light tarmac and concrete do not seem to suffer from snow retention any more than the roads in black tarmac (for equivalent traffic volumes). ”
    —…—…—
    Not true at the lower latitudes – where the physical (geographic) majority of the US streets and cities are located: You are relating to (your experiences in the limited) the UK totally bounded by Lat 50 to Lat 58. Madrid (Lat 40) and Lisbon are approximately the latitude of Montreal and Detroit — and THEY are considered the “far north” as far as the mid-summer heating impact of the sun goes in the US!

    Jacksonville, New Orleans, El Paso and Los Angeles are the same latitude as mid Algeria – in the center of the Sahara Desert, Libya, and northern Egypt. There can be NO (logical or meaningful) “legal” or national requirement or laws or regulations or payments for this ridiculous idea because of the vast changing local environment atop every building and road across the US. Will that prevent Washington from mistakes in this issue – particularly because of the ig-Nobel people proposing it for political gain?

    Of course not.

    Read the full study: Do they mention the “benefits” of greater warmth in the winters balancing the mid-summer heat? CAGW theory holds that winters and nighttime temp’s get warmer, but summers no hotter. So what are the “real assumptions” behind this charade of “reducing” summer heat loads? Aren’t they from the same people who create the wind turbine economic justifications for rate subsidies? From the same people who create the myths of “creating green jobs”? Are warehouses and large (flat-topped) factories and buildings actually air-conditioned? The ones I’VE been working are not! Across the south, midwest, and west, are the buildings and factories wedged up against one another like they are in the (old and increasingly decrepit) Baltimore-Washington-Philly-New York-Boston corridor of ancient rust ruins?

    EXCEPT in these Bos-Wash canyons of old buildings and wedged together streets, everything I fly over each day are spread out – with less than one percent being roads or building roofs. The rest? Trees, lawns, fields, lakes, forests, farms, national and local parks, and utility easements like under power lines, beside railroad tracks, and beside and between roads. Is THAT little number in this study? Who will pay the extra heating costs each winter?

  149. Spector says:
    July 23, 2010 at 5:40 am
    “One should keep in mind that a dark, high emissivity road surface is also more prone to radiative cooling at night in the winter, as those who may have had the misfortune to encounter ‘black ice’ at high speed may know only too well.”

    True, but the thermal emissivity of light-coloured roads may be just as high (or even higher). The reflectivity in the visible spectrum has no direct bearing on this. I suspect it’s more to do with the smoothness of the surface the ice coats. A rougher surface will also tend to lead moisture away by capillary wicking. It would be interesting to see what would happen if one painted those ice black spots with aluminium paint.

  150. Has anybody bought into the “idea” of trying to DRIVE into the sun (morning or evening!) when it’s reflectivting OFF OF a reflective pavement?

    Remember – The CAGW “concept” and theme itself is false: We do NOT need to spend ANY money “stopping” something that is a false premise, and we need to spend NO money against ANY theme that promises NO harm of any kind to ANYONE for temperature increases of less than 3-4 degrees.

  151. RACookPE1978 says:
    July 23, 2010 at 1:11 pm
    “Has anybody bought into the “idea” of trying to DRIVE into the sun (morning or evening!) when it’s reflectivting OFF OF a reflective pavement?”

    No, they haven’t, because no one has suggested it. Stop attacking strawmen. Light-coloured road surfaces are effective at increasing albedo and are pleasant to drive on. They do not reflect the low sun into your eyes. They are actually slightly easier on the eyes than black tarmac, because there is less of a confusing contrast between bright sky and dark road. We have both sorts of road here and I have driven on both and checked this point over the past few days. Furthermore, there are positive advantages in controlling the albedo of cities that have nothing to do with AGW, so rejection of the latter is not a good excuse for attacking the former.

  152. Had two large buildings old roofs stripped and redone. Cost over $10,000 but well worth it as the several layers of old roofing leaked.

    The new stuff is a very thick poly-something that can only be stuck together by heating then pressing with a heavy roller. Under that is 1/2″ of heavy expanded foam insulation with aluminum foil on its bottom side. (Not styrene foam, some other plastic.)

    The top is white and the buildings are much easier to cool. The insulation and radiant heat reflecting foil should make the buildings easier to heat this winter.

    An extra benefit with this stuff is that when it has snow or frost or water on, it’s nearly frictionless, so snow should slide off even though the roofs aren’t sloped much. For extra-extra benefit the several layers of old roofing on each building weighed around 6,000 pounds* (the loads of junk were weighed at the dump) and the new roofing weighs much less, so there won’t be a danger of the roofs caving in under a heavy snow load – if snow can stay put up there.

    So I’ve done my part for the white roof campaign. My house has a galvanized steel roof, so that’s even more reflective.

    *The smaller building had 7 or more layers built up, various sorts with tar paper or fiberglass and tar, lots and lots of tar. The bigger building had ‘only’ its original tar paper and tar layer and three layers of roll roofing, which is paper coated with tar and small granules of crushed rock.

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