Whitening the world's roofs would offset the emissions of the world's cars for 20 years, according to a new study from Lawrence Berkeley National Laboratory.
Overall, installing lighter-colored roofs and pavement can cancel the heat effect of two years of global carbon dioxide emissions, Berkeley Lab says. It's the first roof-cooling study to use a global model to examine the issue.
The study used a global land surface model from NASA's Goddard Space Flight Center, which contained regional information on surface variables like topography, evaporation, radiation and temperature, as well as on cloud cover, Berkeley Lab says.
Lightening-up roofs and pavement can offset 57 billion metric tons of carbon dioxide, about double the amount the world emitted in 2006, the study found. It was published in the journal Environmental Research Letters.
Researchers used a conservative estimate of increased albedo, or solar reflection, suggesting that purely white roofs would be even better. They increased the albedo of all roofs by 0.25 and pavement by 0.15. That means a black roof, which has an albedo of zero, would only need to be replaced by a roof of a cooler color -- which might be more feasible to implement than a snowy white roof, Berkeley Lab says.
The researchers extrapolated a roof's CO2 offset over its average lifespan. If all roofs were converted to white or cool colors, they would offset about 24 gigatons (24 billion metric tons) of CO2, but only once. But assuming roofs last about 20 years, the researchers came up with 1.2 gigatons per year. That equates to offsetting the emissions of roughly 300 million cars, all the cars in the world, for 20 years.
Pavement and roofs cover 50 to 65 percent of urban areas, and cause a heat-island effect because they absorb so much heat. That's why cities are significantly warmer than their surrounding rural areas. This effect makes it harder -- and therefore more expensive -- to keep buildings cool in the summer. Winds also move the heat into the atmosphere, causing a regional warming effect.
Energy Secretary Steven Chu, a Nobel laureate in physics (and former Berkeley Lab director), has advocated white roofs for years. He put his words into action Monday by directing all Energy Department offices to install white roofs. All newly installed roofs will be white, and black roofs might be replaced when it is cost-effective over the lifetime of the roof.
"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," he said in a statement.
Yah...your mother always told you to wear light colored, breathable clothes during the summer, didn't she?
Why haven't we done this before? It almost seems ridiculous that all or most rooves aren't white/light colored to begin with (especially in warm/hot climate areas that need a lot of A/C).
I mean, it's not exactly rocket science here. Black cars get extremely hot in the sun while light colored cars don't.
There should be a new mandate that forces most, if not all homes to have light rooves or install something that will reflect back the heat/energy from the sun to help cool down buildings in the summer.
It doesn't take a genius to figure that out. Same thing with roads but you can't make them white it would be too glaring. Cement them would help though as it is nearer white color than pavement. Pavement is a stupid highway topping. It just caters to big oil's greedy hands.
Better yet lets' all go back to gravel roads. The resulting dust storms would block tremendous amounts of sun shine and the earth would probably going into an ice age!!!
Mankind has all kinds of ways to regulate temperature if it just has the gumption to enact them. The problem is not methodology but rather it's a problem of applying will power.
And so long as congress caters to big oil well be bed ragged bankrupt Americans before long. We simply cannot afford big oil.
how would it only offset co2 once? they would reflect sunlight everyday
Two words. Mirrored shingles. Just give out free sunglasses to everyone and you'll be saving the environment in NO time! And mirrors are made from sand, which is EVERYWHERE!! So just scoop up the eastern seaboard, make thousands of square miles of mirrored roof tiles, and get to work.
Why do something simple and logical like this when you can have so much more fun wrecking the economy with carbon taxes? I think the reason we don't already have white roofs everywhere is that no one in Congress thinks white roofs would help them get re-elected.
@rpenri A true liberal sheep who follow his masters wherever they go. Hey some guy said this will help the environment. 5 seconds later... *angry voice* We must make it illegal for anyone to have a roof that is not white. These evil people with their dark roofs should all be hauled to jail.
Im not saying white roofs are a bad idea. Im simply commenting on the religion held by liberalists.
Sometimes I wonder about these so called experts.
The solution to warming is to use plants to absorb energy.
All they are doing is reflecting the energy back up into the atmosphere where it isn't needed.
The problem with cities is they made a desert out of concrete. Making it a white desert won't help. Study the desertification of Texas or Sahara. Loose plants then temps go up and then desert.
PLANT anything green. Trees, grass, algae, anything green would absorb a huge amount of energy. It really is a free AC system for the earth.
@jefro - what's someplace like NYC supposed to do, build corporate tree houses??? don't get me wrong, I'm all for the whole plant idea to conserve energy (and maybe more importantly prevent flooding of urban areas where there is practically nothing absorbing rain water anymore), but it wouldn't be much of a city if it wasn't cramped as all hell with people, buildings, and vehicles. I mean, where can you find the room for all these plants?? Even if it's one of those rooftop gardens, it's the same square footage of solar absorption as a light colored roof, but you've just quadroupled (sp?) the weight you have sitting 50, 60 stories high from the weight of the plants, soil, and stored water. The light colored roofing idea is a great place to start, and something that can be done rather quickly at not too much of a cost to the building owner - roofs have to be redone every so many years anyways so why not just slap some lighter materials on roofs whenever the time comes to reroof the building.
Seems like a waste of money... why can't we just install Cal-Tech's New Solar everywhere instead?
@ Varsity - Because it costs an arm, a leg, and then some. If you want to pay for the production of all those solar panels, go ahead.
Ideally this would be the norm for nearly every house in America as the idea that white objects reflect back more radiation than darker colors is elementary. I doubt "home investors" aren't going to go down without a fight though, that with their obsession of property value and addiction to aesthetically pleasing exteriors. T__T
costs? pretty sure cost is offset by production of energy. and if there was not as many taxes and other restrictions on solar panels, it wouldnt cost as much. and with increase in demand, the cost lowers.
We need the Myth Busters on this right away!
So we can offset the thermal damage caused by all the black solar panels being installed?
I'm a real estate agent in southeastern virginia, and when I brought this concept up to a group of people a couple of months ago I was told emphatically that this is not something that most people would be on board with. They literally thought I was crazy. Why were they so against it? Because the roof would get dirty and it would look bad. Home Owners Associations would freak out. There still just aren't enough people who care, and would prioritize the environment over the appearance of their home. It's disappointing, but it's up to people who care to help educate everyone else about the actual impact of their home, how important it is that we change, and the simple things we can do to make that happen.
Well now, how about the northern areas that have significant parts of the year when the heat gain is a good thing? As a matter of fact, if we could keep the 'snowy white' snow off of our roofs for the whole winter, it would probably be a good thing.
We run our a/c from mid May through part of September. So, there are about 5 months of cooldown vs seven months of heat up.
My heating bill is significantly higher than my a/c bill.
Maybe variable color roofs :)
This is common place in Arizona. It really helps shave down the air conditioning bills. Even better though would be covering those roofs with solar panels.
So let's not spend that money on reducing the emissions. Lets just paint the roofs white. Well in the winter it takes more power to heat. And cities like mine in the desert we have ceramic tile roofs already. So where are all these evil black roofs anyway?
These so called experts are morons. Spend some more of our tax dollars on this stupidity.
Skyscrapers should have parks on their roofs.
I like the solar panel idea.It would displace lots of coal-fired power plants year after year.To add to that,how about "solar roadways"? The idea is to replace worn out asphalt roads with standardized super tough solar panels.The company involved has gotten a small grant from the feds to develop the idea. Google it,as I got accused of spamming the last time a posted a link.
A thought occurs to me. Where I leave he have what is described as a heat bubble caused by the city. This bubble blocks incoming weather patterns from actually forming over the city many times. What is funny is that most of this cities rooks are at least lightly colored though not white. The locals science suggest that the heat we are reflecting back at the sky is part of the reason the clouds usually don't quite make it to the center. Then of course we have the heat bubble cause by pavement and building materials ability to hold heat as well.
On the flip side of the white roof. If they made coating for cooler climates that changed to dark colors when exposed to col and light colors when exposed to heat would that not enhance this idea even more?
Great idea - helped my dad paint our roof white 45 yrs ago.
One prob is that people will think that that is problem solved - & will continue to emit CO2. Prolly we have to wait for seas to die from acid before we realize we cannot continue like this.
It is a great contributor to the solution but only in conjunction with zero fossil fuels.
This is a great idea in places like Georgia, Alabama, Mississippi, Florida, Louisiana, Arkansas, parts of Texas and New Mexico and Arizona, and probably southern California...
BUT, Electric consumption of air conditioners is not the only consideration to take into account. There is a thing, that foils the brains at Lawrence Berkeley National Laboratory, called Winter. Anywhere in the United States, or the world, not located within very close proximity to the sub-tropics gets cool/cold. The thermal effects of the sun on roof tops keeps them clear of ice and snow. We would have to completely re-engineer and rebuild the roofing systems of every building standing in those regions to allow for the potential loads. The safety of those near the exterior would have to be accounted for, as we would have a falling load hazard overhead every building. We would have the added industrial emissions of factories firing up to meet the initial and continuing demand for the new 'style' of roofing that is not a standard, so it would have to have a specialized manufacturing regiment, thus different factories making the components. This is a great way to pollute more in the name of 'saving the planet'. Sounds to me like no one at Lawrence Berkeley National Laboratory has ever stepped out of the lab for more than a latte at 5 bucks. :s
A better solution would be to have say the engineers and architects of a particular region design and implement solutions that are very specific to a structures locality with energy conservation and function in mind... Wait, that is what already happens ever day, never mind, the Energy Secretary of the United States of America is an idiot or he would have thought of that first.
I am not even going to go over the selection of materials for roadways and parking lots. That is a very regional issue as well.
If anyone really wants to solve a problem like this they are going to have to discover/develop materials that will allow for conditions that vary from season to season, and not simply make a generalized assumption that because a thing works well in one instance, that it is an obvious choice in all instances. Otherwise, every hack that has proposed a theory would have us say, "He made this work once. It must be a fundamental law, like E=MC^2."
It scares me that so many would ignore reason and blindly agree with Lawrence Berkeley National Laboratory & the Secretary of Energy, simply because they all have a piece of paper with the letters ph&d stamped on it. I will take wise over smart any day of the week.