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Kevin Matthews
Joined: 13 Apr 2004
Posts: 489
Location: Eugene, Oregon
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lekizz
millennium club
Joined: 11 Jan 2006
Posts: 1015
Location: UK
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 Posted: Mon Oct 29, 2007 6:02 am Post subject: |
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| Quote: | | Brenneisen also found that many sedum roofs have minimal positive effects on storm water retention, energy use, or the urban climate — core arguments that have been used to justify the implementation of green roofs. Moreover, ecologists attribute rather limited biodiversity values to sedum roofs and prefer roofs that offer a secondary habitat to endangered plant and animal species. |
Basically the same point I would have made, the slim sedum roofs are designed more to solve economic than environmental factors. They certainly protect the roof surface, look 'nice', have minimal maintainance costs and also say 'this building owner must be environmentally concious and right-on' 
An astute and useful article. |
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Kevin
Site Admin
Joined: 13 Apr 2004
Posts: 1086
Location: Eugene, Oregon
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| Posted: Thu Nov 01, 2007 10:40 am Post subject: |
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Thanks much. We're in an interesting stage of green building - it's "in" enough that many want to get credit for doing it. But it's still new enough for most (among other things) that what is superficial and what is deep is still very much in play. And so it will be for many years to come. We're making progress, but we have a long way to go.
And that's even without getting into the realm of conscious greenwashing.
I really love the example of the 90-year-old roof in Moos that has grown up simply to become an important biological refuge in its own right, long-term home to hundreds of endangered plants! |
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TJCaine
Joined: 06 Nov 2006
Posts: 53
Location: New York, NY
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| Posted: Wed Nov 14, 2007 12:27 pm Post subject: |
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To say there are no environmental aspects met is not really accurate, there are actually a number of environmental ends that can be accomplished with a thinner or more "extensive" green roof system such as trays. Here at the office of the firm I am working at we installed a green roof in downtown NYC. We used a bag systems that used a stone/soil mixture within a plastic version of burlap. Once the bags are filled and installed holes are cut in the tops and three sedums of different varieties are placed in the top. This was done in June '06 and the entire roof is now a green flowering carpet.
So what green ends does this really accomplish. The first is managing storm water run-off--a drastic problem in NYC or any post-industrial american city that works off of a Combined Sewer Overflow (CSO) system. The soil and plants absorb a level of water that allows for a more gradual release of stormwater over time.
The second is lowering the temperature of the roof. Our office took readings of the roof in the dead of summer in full sun before the green roof was installed. We found it as a black beach... all black rubber. The temperatures were measured upwards of 140 degrees. After the green roof addition, the roof surface was as low as 65--a 75 degree difference. The benefits are pretty easy to extract from there. The building takes on less heat, uses less energy, certainly green. Also they are an insulator in the winter.
Also, not to be lost is the ecological aspect of the green roof. Urban landscapes become barren of natural life, in part due to the heat islands that are created that make environments that insects and birds cannot possibly live in. Our roof alone is now home to tens of species of bugs, which in turn brought birds, which in turn brought kestrels (birds of prey.) It's really it's own little ecosystem. The Monarch butterflies migrated through NYC this year and for days we literally had two dozen of them sipping from sedum flowers. Think what would happen if you had an entire block done?
Rest assured, you don't need a multi-layered green roof 24 inches thick to make an environmental impact. |
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