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Green roofs
March 12, 2005 6:13 PM   Subscribe

Green roofs "are living, vegetative roofing alternatives designed in stark contrast to the many standard non-porous roof choices."
posted by dhruva (22 comments total)

 
And there's also Green Roofs for Healthy Cities, the nonprofit umbrella group. Some of the winners of last year's awards are pretty neat.

(NB: declaration of interest; I worked on the greenroofs.org website.)
posted by scruss at 6:32 PM on March 12, 2005


Hell, I've been thinking about doing a green roof. I now live in a West Coast Contemporary home, with a flat-top roof.

Anyone have any personal experience with green roofs?
posted by five fresh fish at 6:35 PM on March 12, 2005


Speaking from experience, I prefer my roofs non-porous.

But these aren't really non-porous, and they're great. It's one of those ideas from your childhood that seems so intuitively obvious, but that just isn't done in real life (much).
posted by smackfu at 6:35 PM on March 12, 2005


one of the images on that site:



This is an auto-manufacturing plant done for Ford by architect William McDonough and he showed this image in a recent presentation to my university (UC Boulder). His design philosophy is brilliant. It stemmed from a few points:

a) The environmentalists aren't getting us anywhere with the "reduce, reuse, recycle" discourse. The metaphor he gave was that if you're driving north to mexico from colorado slowing down isn't going to get you there any faster. What we want upcycling. The epitome of this concept is his book, Cradle to Cradle: Remaking the Way We Make Things, which is made out of plastic and is capable of not being recycled, but actually melted down and turned into something of a higher quality. That's the concept behind upcycling. Recycled anything is just on a longer road to the landfill, but it's still goin'.

b) You should blend in with the local ecosystem and make as small of an impact as possible. This includes giving the space your design takes up back to the ecosystem, in the form of what you see here: a lawn or native plant species on the roof. He said something like 28 species of birds had been spotted on the roof.

c) There is an important dichotic split in design materials. You have technical materials and natural materials. You should never mix the two, and any time you use technical materials it should be in a manner that they are not to be recycled, but rather upcycled.

I highly recommend his book. McDonough's ideas are already in full swing, with Ford naming his vision of the future of the automobile the Model U (think: successor to the Model T) and the government of China (yes, that China) formally adopting Cradle to Cradle as their growth strategy.

You gotta' love a guy who critiques both capitalists and environmentalists at the same time while becoming filthy rich and succeeding.
posted by reflection at 6:46 PM on March 12, 2005


I'm curious about one thing. In the cross section there is a layer that makes me concerned. The root resitant layer...is only resistant. So can you expect root damage - particularly since things like grass can grow through concrete (up mind you but how strong are root systems)? Once you have root damage how do you fix it? Do you go up through the inside or do you have to dig through the other layers to patch the root resistant layer?

That said...I like the idea...because most roofs are ugly.
posted by srboisvert at 7:14 PM on March 12, 2005


I had wanted to do this with my deck; anyone with any input on carrying this off on a smaller scale (as in, without the resources of the Ford corporation), please chime in!
posted by jonson at 7:18 PM on March 12, 2005


Without visiting any of the links, I have to say.. I saw a news story about this being done in Chicago (I think) about 5 years ago, and I wondered why it wasn't universal in cities in the U.S. and South America. If you build a flat-roofed building, provide for a layer of dirt and grass on top... you don't have to go the whole garden route.

This would not only help things like CO2 pollution, it would help prevent the formation of urban heat islands, which are a weather phenomenon where cities like Atlanta and Houston are changing weather patterns by creating these huge columns of hot air thanks to all the flat black roofs in their city core.
posted by BoringPostcards at 7:42 PM on March 12, 2005


Grass is a bad idea to go on a roof- their water consumption levels are disgustingly high and the ecological tradeoff wouldn't be worth it. The idea is to go for low-maintenance plants that reduce the heat signature without asking for too much in return. Grass might cool things down a bit but when you factor in the cost of that much water, you're still wasting resources.
posted by BuddhaInABucket at 8:05 PM on March 12, 2005


I read about this is Mother Earth News not too long ago. Too weird for me personally but quite a kick. ME News is a very good homestead magazine, btw.
posted by puke & cry at 8:30 PM on March 12, 2005


The "grass" on the Rouge Plant roof is really sedum, which is a hardy perennial, and doesn't need nearly as much water as grass. iirc, the irrigation system on the Rouge roof was only used in the first summer, while the plants were getting established. Sedum roots aren't as invasive as grass, either.
posted by jlkr at 8:32 PM on March 12, 2005


reflection, you can't melt a polymer item down and create a higher quality item from it. Polymers degrade slightly when you heat them. The inks and fillers in the book will contaminate the melt, and so you'll end up with a lower-grade plastic. It's just entropy, nothing personal.

I do find it amusing that Ford are now getting all preachy about extended producer responsibility (which Cradle to Cradle is, just reheated some) after fucking over the planet for the last century.
posted by scruss at 5:14 AM on March 13, 2005


I'm in Berkeley, also contemplating making up some test roof boxes -- main longterm concern here would be fire. California's native plants are well adapted to burning every decade or so (the California Native Plant Society had a wonderful T-shirt -- horizontal line, with three or four little leaves and stems above it, and a huge root structure below).

Fitting that onto a thin flat roof is a problem. The sedums are about the only choice.

Weeding is going to be an issue though, when the spring rains come, there are weedy annual grasses popping up, going to seed and ready to become crisp brown fuel as soon as the weather dries out (California used to be green year-round, before the Spanish brought in annual Mediterranean grasses that go to seed and die.

Still, a very tempting idea.
posted by hank at 9:26 AM on March 13, 2005


Hadn't thought about the crisp brown fuel problem. I live in the Okanagan, which is about as close to desert as you're going to find in Canada. Any green ground cover becomes crispy brown by the time summer hits. Perhaps not the best roof cover.
posted by five fresh fish at 9:47 AM on March 13, 2005


fff and jonson,
The Chicago Center for Green Technology is another good place to go for info. There's a pdf guide on their how-to page.

I got a chance to tour the CCGT last year and see their roof garden up close. The sedum they'd planted wasn't particularly beautiful, but it's not supposed to be since it's just up there on the roof doing its job. But it might not be the nicest thing to put on a deck.

I think I remember that the advantages of sedum were its hardiness and that it would grow into a very thick cover, so no weeding would be required after a year or so. This was Chicago, though. Maybe the grasses in California or the sun in the Okanagan require something different.

scruss,
The ink in Cradle to Cradle can be separated from the plastic pages by a hot water bath, according to McDonough and Braungart .

And thermoplastics can be heated down and reused without much if any loss of quality, can't they? Plastics manufacturing plants already do this with their waste (flash and mistakes). They grind it down and put it right back in the hopper. They do it because it's good material, a resource they don't want to lose, not necessarily because of any altruistic concerns. They can because the waste is clean and it's a closed loop, not a random mix of plastics and colors. No entropy yet. McDonough and Braungart are saying that with a more work on the design end, stuff can be made with recovery of the materials built into the system. And companies would want to do this because it's an advantage for them.
posted by hydrophonic at 10:08 AM on March 13, 2005


hydrophonic, so I guess the book is recyclable with the craven caveat where facilities exist. I'm guessing that hot-water book dipping plants aren't that common yet, so maybe it should be when facilities exist? One probably has to be careful of reading this book in the bath, or spilling tea near it.

There will always be a slight degradation in the polymer chain length, and in fillers, brighteners, and pigments in remelting scrap. Manufacturers control this by limiting the percentage of recycled material against new. So while the amount of uncontrolled crud is low in pre-consumer waste, the process cannot be perfect.

EPR's an old, old idea. In fact, I'd say it's only recently that manufacturers stopped taking responsibility for their products' service life, with the advent of mass production.
posted by scruss at 10:32 AM on March 13, 2005


One probably has to be careful of reading this book in the bath, or spilling tea near it.

McDonough and Braungart say it'd be fine in the bathtub, even better than a paper book. I don't know about a tea spill. I'd try it, but my copy is from the library. They do admit that their book isn't perfect yet. The cover is regular paperboard, I think, and there are string and glue in the binding. And there's the lack of facilities, as you say.
posted by hydrophonic at 12:48 PM on March 13, 2005


Plants in genus Jovibarba (Jupiter's Beard) were once planted on roofs in Europe to ward off lightning strikes. I guess this would have to be considered technology that has been superseded.
posted by ackptui at 4:02 PM on March 13, 2005


I like reading about stuff like this. I suppose someday society and architects will evolve to use materials other than concrete, steel and glass; but probably not for a while.
City architecture has embraced mediocrity for so long that to change it now might be too revolutionary. Besides, if the building cost 30 million; certainly can't spend another million on the roof unless it is a swimming pool.
posted by buzzman at 6:00 PM on March 13, 2005


Chicago is, counterintuitively I suppose, a leader in this movement, largely thanks to evangelical zeal on the part of Mayor Daley -- he hopes to make Chicago the greenest city in the US. Daley began his career by ordering the city to plant more trees, and over the years many broad, ugly thoroughfares have been transformed into boulevards separated by raised concrete plantings (hated, of course, by many drivers), including Lake Shore Drive. It isn't just one thing; he has a sense of the importance of the urban environment (a quirkier favorite of his is iron fencing, which now encloses many city parks). The installation of the city hall green roof was a spectacle watched with interest by people in nearby skyscrapers, and since then a few private buildings have installed less ambitious rooftop plantings.

But these aren't really non-porous

The "porous" here doesn't mean the rainwater goes through the roof into the building. It means that the rainwater is captured and put to use instead of being washed straight into the city storm drain system.
posted by dhartung at 7:28 PM on March 13, 2005


I'm actually sitting writing this in a building with a green roof, I'll see if I can get some more info on what we have planted up there as the architect occasionally pops in to my corridor. The roof is covered with some grassy material and I'm pretty sure isn't provided with any water other than through natural precipitation. It's not a lawn, more a sort of rough reddish grass. Alas we're not allowed out there as yet as they need to put fences round the perimeter but fingers crosses that they will sort this out by the summer as we have some amazing views.
posted by biffa at 3:33 AM on March 14, 2005


we're not allowed out there as yet as they need to put fences round the perimeter

Ah. The "attractive nuisance" thing rears its ugly head again.

You just know you'd try to leap across to the building next door.
posted by five fresh fish at 9:34 AM on March 14, 2005


More that you can't trust students not to chase frisbees.
posted by biffa at 9:40 AM on March 14, 2005


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