Archive for Sunday, June 14, 2009

White rooftops may help slow warming

June 14, 2009


Not always costlier, but harder to look at

To get all the benefits of a white roof, plain old white paint will not do. Instead, the roofs should be covered in a reflective coating, or a specially made membrane (Details about cool-roof products approved by the Environmental Protection Agency can be found at——roof—products).

The result: White roofs are not always more expensive than dark ones. But they can be a lot harder on the eyes.

“It’s like being in Antarctica or the North Pole or something. I mean, you need to wear sunglasses,” said Albert Nunez, vice president of Capital Sun Group, an installer based in Cabin John, Md. When he pitches it to customers who have a slope-roofed house in the suburbs, he said, “The wife looks at it and says, ‘No, I couldn’t do that to Sally next door,’” Nunez said.

— Could climate change be staved off by making the United States look like the set of “Mamma Mia!”?

That was suggested in a recent talk by Energy Secretary Steven Chu — although, because he was speaking to Nobel laureates, he did not mention the ABBA musical set in the Greek Islands. He said that global warming could be slowed by a low-tech idea that has nothing to do with coal plants or solar panels: white roofs.

Making roofs white “changes the reflectivity ... of the Earth, so the sunlight comes in, it’s reflected back into space,” Chu said. “This is something very simple that we can do immediately,” he said later.

Chu has brought increased attention to an idea that — depending on your perspective — is either fairly new, or as old as Mediterranean villages, desert robes and Colonel Sanders’ summer suit. Climate scientists say that the reflective properties of the color white, if applied on enough of the world’s rooftops, might actually be a brake on global warming.

But if anybody is seriously considering a global whitewash, “simple” and “immediate” are probably not words that come to mind.

“I don’t think that it could ever be done at a sufficient scale,” said Ken Caldeira, a climate scientist at the Carnegie Institution in Stanford, Calif. He added: “It’s hard enough, in many of the cities of the world, to keep the streets swept, much less to keep the city reflective.”

White roofs work because of the physics of sunlight. Dark roofs absorb and hold more than 80 percent of solar energy, while white ones can reflect 75 percent of it away. That makes a white-roofed building cooler and cheaper to air-condition.

Because of that energy savings, California has since 2005 required most flat-roofed buildings to have white tops, and Wal-Mart has installed them on about 75 percent of its U.S. stores. In January, Washington D.C. will require new flat roofs on commercial buildings to be covered in vegetation or a reflective material.

Now, scientists are wondering whether white roofs might keep the world cooler, too.

The idea does not treat the root cause of climate change, which is heat-trapping pollution such as carbon dioxide and methane. But white roofs do help with the primary symptom: heat. The light they reflect escapes through the polluted atmosphere like a BB through a greenhouse.

“We may have to figure out a way to artificially cool the planet while the atmosphere is still super-saturated with greenhouse gases,” said Mike Tidwell of the Chesapeake Climate Action Network. This could be it, he said, “because the planet, it’s a closed system, it’s an absolutely closed system, except for one thing: sunlight.”


imastinker 8 years, 11 months ago

This has got to be about the stupidest thing I've ever heard.

Let's use his numbers: a white roof reflects 55% more energy. Let's figure that .001% of the earths surface is covered by a roof. Can anyone do the math here?

Let's not forget that in winter dark roofs can help increase solar gain during the day, resulting in lower fossil fuel usage.

I've got the net benefit at zero or too close to measure.

WHY 8 years, 11 months ago

Don't use math. Use your heart. Painting my roof white makes me feel like I am doing something for the environment like when I use my reusable bag to go to Walmart and buy a bunch of stuff I don't need. If it feels like it helps then it must.

tunahelper 8 years, 11 months ago

more pseudo-science from algore and his minions! we need to nip this crap in the bud before the average dumb American believes this as fact.

what a bunch of stupid leftists!

feeble 8 years, 11 months ago

glad to see the usually know-nothing, doom and gloom crowd is out today.

Here's the white paper on the idea:

The Wall Street Journal reported on this almost a year ago:

aaaand here is a brief presentation from a group at Lawrence Livermore labs who studies the Island Heat Effect:

But since we all know tunahelper is a card carrying climatologist and physicist, we can just ignore those PhD's in favor of his ignorant, two-bit, asinine, partisan hackery!

imastinker 8 years, 11 months ago

Feeble- you have a dead link and an article that has at least some facts but not enough to refute the simple math I did. If you are going to call me a know nothing at least show me how you have better information or I'll have to assume you don't.

just_another_bozo_on_this_bus 8 years, 11 months ago

"Global warming is a part of the evolution of this planet. It has happened before, without the issues of fossil fuels."

Wholly irrelevant. While there have been periods of higher greenhouse gas concentrations and the resulting higher temperatures and other climatic differences, there have never been nearly 7 billion humans on this planet, all of them wanting to use up all the fossil fuels generated in previous periods of global warming. It took millions of years to store up all that carbon and all that energy, and we're releasing it in a matter of a few decades.

Simple fact is, that's never happened before, and trivializing by saying it has is nothing but wishful, thinking-- and if you really wish for the human race to survive, it's pretty reckless.

jaywalker 8 years, 11 months ago

Now if we could just figure out a way to turn cow flatulence INTO white roofs we'd really be onto something!

just_another_bozo_on_this_bus 8 years, 11 months ago

Imastinker-- no one is saying that this measure will stop global warming. It's merely one part of probably thousands that will be required in solving that puzzle.

At any rate, I suspect your back of the envelope calculations are just wrong.

Leslie Swearingen 8 years, 11 months ago

Argentina's Perito Moreno glacier is one of only a few ice fields worldwide that have withstood rising global temperatures. What is that supposed to prove, pro or con?

Richard Heckler 8 years, 11 months ago

Reversing green house gas will require:

White Roofs 97% HVAC systems Energy Efficient Windows proper insulation retail shop owners NOT air conditioning the outside Buildings meeting LEED specs walking biking driving 36 mpg or better cars the lions share of the time computerized thermostats wearing sweaters and light jackets inside during winter going naked inside during hot summer months more socializing and dating on feet and bicycles stopping the war and all of the pollution created by hummers,trucks,tanks,low yield radioactive weapons,airplanes/fighter jets,chemical warfare cutting grass less often developing hydro power,solar power and wind power to the fullest extent move closer to work if possible stop buying water in plastic bottles/ use stainless steel bottles over and over and over again...will fit into bicycle water bottle cages building energy star homes making biking and walking surfaces safe to travel

just_another_bozo_on_this_bus 8 years, 11 months ago

"Global warming is going to happen, with or without intervention. It is a part of the evolutionary process of the earth."

Talk about a tautology. Of course whatever happens will happen because of "evolution" -- humans are part of the evolutionary process, even if we do go the way of the dodo bird.

Is there any difference between this global warming happening in the next few decades because of human use of fossil fuels, which are almost certainly causing or accelerating it, and its happening ten or a hundred thousand years from now through processes not caused by humans?

Or is your point merely that we're all going to die anyway, so why should anybody do anything to prolong their measly existence on this planet? Extinction is our only predictable fate, so why fight it? Should we all become jihadis and blow ourselves up on the slim chance that we really will get 20 virgins when we die?

BrianR 8 years, 11 months ago

barrypenders (Anonymous) says… "I bet the Wal-mart he shops at is cool too."

A Wal-Mart in a cave! I like it.

ASBESTOS 8 years, 11 months ago

Bozo wrote:

"Simple fact is, that's never happened before, and trivializing by saying it has is nothing but wishful, thinking— and if you really wish for the human race to survive, it's pretty reckless."

Well if this is from the 7 billion people wouldn't it behoove us to "depopulate"? A couple of wars and plagues should do the trick. (Rolling Eyes) As Ron White says"I'm eating the cows".

What are you People thinking?

camper 8 years, 11 months ago

Well this is what I'm thinking. If by even the most remote percentage, humans are causing global warming, we should take it seriously and think strategically for future generations. If not, history won't remember us too kindly....probably a couple of steps behind the Romans who used to watch Gladiators.

Regarding white roofs. My idea would be to install black solar panels on top of them instead. Hopefully these panels would be built and serviced by our own workforce (atleast before we export this technology).

So I'm for green technology for many reasons. I even agree with McCain's "all of the above" approach he talked about in the election. I don't think we should allow the uncertainty and science behind global warming prevent us from sound energy stategy for us...and the future generations.

imastinker 8 years, 11 months ago

"The world’s temperature monitoring stations won’t even be able to measure it."

Don't worry. Bozo will be able to do it for us.

just_another_bozo_on_this_bus 8 years, 11 months ago

Not at all-- They've been put to work painting the town white.

Chris Golledge 8 years, 11 months ago

I don't know about white roofs; just offhand, I think I pay more to keep my house cool in the summer that warm in the winter.

Monckton is a fraud.
a) What research has he ever managed to get published in a peer-reviewed journal?
b) He has been debunked many times over. Here is just one example,

Chris Golledge 8 years, 11 months ago

On the credentials line, maybe you didn't notice

"Copyright © 2009 by Christopher Monckton"

at the bottom.

Maybe this will shed some light on your illustrious protaganist,

muddfoot55 8 years, 11 months ago

It may save summer energy but a white roof is not going to help the snow melt in the winter. savings or a totally new roof and rafters? That's a tough choice.

Bossa_Nova 8 years, 11 months ago

ice age is the wave of the future! caribbou unite!

feeble 8 years, 11 months ago

not sure why the first link in my previous comment died, here is the actual article:

for all you number crunchers out there, this has nothing to do with the total surface of the earth, so .1% assumptions are meaningless. Dr. Akbari's calculations only include urban areas. His figures arrive at a one time savings on 11 trillion dollars in reduced energy costs for cooling businesses and homes.

However, if you really want to see where your back of the envelope figures go wrong, check out page 9, table 5 in the above linked article.

just_another_bozo_on_this_bus 8 years, 11 months ago

"I don't know about white roofs; just offhand, I think I pay more to keep my house cool in the summer that warm in the winter."

Exactly. The point of painting the roofs with reflective coatings isn't to reflect the light (and heat) back into space, although it does-- the point is to keep it from heating up structures that would then need to be cooled down. There would be a net gain for structures at least as far north (and correspondingly as far south in the southern hemisphere) as we are here in Kansas.

jumpin_catfish 8 years, 11 months ago

The sad part is a bunch of leftie wingnuts will believe this crap and their equally stupid buddies in Washington will fund this madness.

kugrad 8 years, 11 months ago

Hmm. Whom to believe? A Nobel Prize winner whose calculations show a very significant benefit that would be part of the puzzle of reducing man's contribution to global warming ....


a bunch of guys who know how to use Google who post to the LJW boards with knee-jerk reactions about anything to do with global warming........


Chris Golledge 8 years, 11 months ago

Marion, You keep trying to hammer home a point, but I'm not sure what it is.

"Argentina's Perito Moreno glacier is one of only a few ice fields worldwide that have withstood rising global temperatures."

It's like saying, 'Hey, here is a business that is doing well despite the recession.' It is bucking the trend; that's why it is interesting. But, that doesn't mean that people who say the economy is in trouble are wrong.

Chris Golledge 8 years, 11 months ago

For what it is worth, I don't think too many people are really advocating ripping off a perfectly good roof, but rather, if and when your roof needs replacing, think about an alternative to the traditional dark roof.

Kind of like not trashing your incandescents, but when they burn out, try a flourescent as a replacement. Likewise, considering the cost/energy used in manufacturing, it doesn't make a lot of sense to get rid of one car and buy another, but if you are trading anyway, look for something with better efficiency.

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