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] 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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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… )

EthicallyCivil

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 🙂 )

Jason Bair

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.

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.

I keep my roof white all winter. The white color keeps the house cold, raising the heating bills.

Paul Linsay

This has been done on the Mediterranean since forever and for the same reason.
Santorini

How much do you save on air conditioning in the summer compared to how much more you will spend on heating in the winter?

Dr T G Watkins

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

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.

Edward Palmer

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!

Leon Brozyna

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.

the fritz

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

Curiousgeorge

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. 😉

terrybixler

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.

Henry chance

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.

Actually there’s a lot to be said for green roofs – cool in Summer, warm in Winter. Grass in wetter climates, succulents in drier ones.

Bill Marsh

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?

Tom in Florida

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?

Ian L. McQueen

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

DirkH

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?

Crispin in Waterloo

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.

Mike McMillan

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.

Gareth

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.

Ed Murphy

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.

Peter S

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.

Bruce Cobb

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.

Bruce Cobb

Oops, by energy savings I meant cost savings.

ZT

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.

Peter Melia

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.

Peter Melia

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.

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.

John Peter

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?

Ian L. McQueen
Ian L. McQueen

John Peter
http://discover.itsc.uah.edu/amsutemps/execute.csh?amsutemps got me an error message both as hotlink and when copied and pasted into google.
IanM

latitude

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

Tommy

All they need to do is change the color!
http://0.tqn.com/d/cleveland/1/0/x/h/-/-/sherwin-williams.jpg

Mike B

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!

Tommy

I just had an ironic thought…
The latest plan to battle global warming: whitewash!

Curiousgeorge

@ 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.

Dr A Burns

>> 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”.

latitude

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

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.

kuhnkat

How do we change between black and white for winter and summer??

Doubting Thomas

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.

kuhnkat

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.

Ray

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

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?

Ray

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

dwb


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.

Ray

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.