Comments on: The best stimulus, Part 1: What is geo-engineering and adaptation and CO2 mitigation all in one?

By: A Siegel

A Siegel — Tue, 14 Apr 2009 04:58:53 +0000

Absolutely spot on.

And, this is something that can be driven quickly via building codes.

There is zero reason for a flat-roofed structure to be allowed to be anything other than a high-albedo or a green roof. Variety of paths to drive this forward, but definitely something to be pushed.

Now, a question is whether getting serious about this could mean a faster than 20 years to make a major dent with reflective roofing?

By: Gillian Ream

Gillian Ream — Thu, 08 Jan 2009 00:31:51 +0000

Cool roofs and pavement are a great, cost-effective strategy to combat UHIM, but before we hail it as the big new solution it seems there are some local issues to take into account.

First, encouraging LA homeowners to plant (and water) more trees to *encourage* evaportanspiration seems irresponsible, considering the semi-arid climate and the already-depleted aquifers. What are the climate effects of the water loss, and wouldn’t it be better used to grow food?

I am also wondering about the efficacy of cool roofs in northern cities like Chicago and Detroit. Does the increased albedo make as much difference with less direct sun exposure? If it does, the cooling argument would be a much more difficult sell.

By: msn nickleri

msn nickleri — Wed, 07 Jan 2009 16:35:00 +0000

Somewhat less effective than white roofs in terms of their cooling effects but more practical in terms of maintenance are “cool colored” roofs and paving materials.

By: Alex J

Alex J — Tue, 06 Jan 2009 04:22:19 +0000

Smithee, I suppose one would need to find out how much solar energy strikes a roof in winter vs. summer in a particular region. And how much of that energy would actually make it’s way into the air-conditioned space. Since most roofs (at least in my area) are ventilated, the bit of heat collected by a black roof in winter would mostly leak out of the attic. In summer, though, we can have very high attic temperatures, with heat buildup exceeding ventilation capacity.

By: Michael P Totten

Michael P Totten — Mon, 05 Jan 2009 20:09:43 +0000

My Jan-Feb 2009 Sustainable Worldview column in Solar Today (American Solar Energy Society) is an interview with Dr. Art Rosenfeld, Calif Energy Commissioner, and Dr. Hashem Akbari, head of the urban heat island mitigation program at Lawrence Berkeley Laboratory. Their most recent report indicates increasing the albedo (reflectivity) of urban roads and rooftops worldwide could prevent 40 billion tons CO2 entering the atmosphere, while accruing cumulative savings of $1.1 trillion. The article is downloadable at: http://www.scribd.com/ doc/ 9615578/ Totten-Solar-Today-Janfeb-09-Cool-Cities

By: Michael Hoexter

Michael Hoexter — Mon, 05 Jan 2009 19:28:48 +0000

Somewhat less effective than white roofs in terms of their cooling effects but more practical in terms of maintenance are “cool colored” roofs and paving materials.

http://www.coolroofs.org/ documents/ CoolColoredRoofs_000.pdf

I believe GAF-ELK has a selection of these as may some other manufacturers.

By: Dano

Dano — Mon, 05 Jan 2009 17:42:22 +0000

My work in this area is in the urban trees strategy.

There is a conference in Berkeley in September about this issue, and what strategies to employ, BTW.

Best,

By: Smithee

Smithee — Mon, 05 Jan 2009 17:07:16 +0000

Will this not also have the effect that houses, and thus appartments are colder in winter, since the few sun rays they get will be reflected, and thus people will need more heating? And isn’t the energetic impact of heating worse than that of air-con? As an european, it seems to me that air-con is just a terrible fad, a habit. When we travel to airconditioned countris we always get a cold, so undercooled buildings are there. A first move might be to tell people to put down the air-con.

By: Daniel Smith

Daniel Smith — Mon, 05 Jan 2009 14:05:16 +0000

This is very nice to see. I’ve been wondering for years why increasing albedo has not been front and center, since it produces such obvious local benefits. But, Joe, Can you say more about why you see this as the single most effective strategy? Has anyone modeled how increasing urban albedo and tree cover will scale up and what sort of cumulative impact it would have? On that count, my gut tells me the effect will be pretty limited, but maybe not.

By: Bob Wallace

Bob Wallace — Mon, 05 Jan 2009 02:38:04 +0000

Gail…

I think you drank from the wrong kool-aide pitcher. That must have been the mushroom one….