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Saturday, September 4, 2010

Green Walls - A Counterpoint

As you can probably guess, I am an interested party in the green wall movement, and intrigued by how they might be useful in Los Angeles from a sustainable and aesthetic perspective.  So, this week provided a couple of interesting perspectives to consider whether green walls make sense in Los Angeles, and if so, in what form.  The first was a blog post on the ASLA Sustainable Design and Development Blog by April Philips highlighting some her own experiments in the performance of green walls in California. Although informal, the experiments provided an anecdotal account of which systems worked best for her.  The second, was a pointed critique of the green wall fad by LA Times columnist Emily Green.  Green cast a strong, skeptical eye and asked some legitimate questions about whether green walls really make sense in an arid environment. Below is a long excerpt:
. . . My own feeling about vertical gardens in Southern California is that they are a plant fetishist’s tool for hastening climate change. Take a look at the Culver City party venue called SmogShoppe,[photos shown on this blog before] owned by the folks selling a vertical garden system called Woolly Pockets. Succulents such as sedum and senecio that are so hardy in the ground need constant irrigation to cope with heat and wind after being suspended in felt pockets against SmogShoppe’s hot walls. The concrete wall behind the bagged-and-hung garden is wet with runoff from an automated drip system. The sacks are calcified with irrigation scale. Even in an open-air setting, get close and there is a whiff of mold. It’s hard to imagine a less savory or more whimsically destructive system for a region in a water crisis.

Recently, L.A. has been gripped by a challenge from the Woolly Pocket manufacturer to put its planting bags on fences in hundreds of schools. I dread seeing abandoned, tattered pocket remnants fluttering from chain link.

School gardens should connect kids with Earth. As for other settings, the idea of using plants to animate walls -- be they in civic arenas, offices or homes -- is intriguing. But if we truly want to accomplish this in a way that speaks to the dry majesty of our region, then the right approach is to leave out the irrigation and work solely with appropriate building materials to create suitable planting habitat -- then seed it. Bring back the lovely old dry stone walls of yore. If you really want to marvel at the majesty of plant life, witness a wild buckwheat flowering from an abandoned stone wall in the foothills.

Proponents praise vertical gardens for beauty. This charm is irrefutable. Just as Turner became mesmerized in Paris, pedestrians stop short before the SmogShoppe. Yet enthusiasts lapse into nonsense when extolling ecological virtues to do with heat insulation and repositories for gray water. If you want relief from the sun, hang an awning, build a porch or plant a shade tree. Gray water is still water, and wasting it is still a socially disastrous idea in the dry West. Far better to put gray water in the ground, where it will be protected from evaporation and remain available to plants.

Finally, there is the energy profile. Roughly a quarter of the state’s energy goes to transporting water; of that, the majority is spent getting it from the Bay Area and the Colorado River to Southern California. Once that water gets here, the region needs a better way to green and cool buildings that doesn’t involve dinky pockets of captive flora.
Overall, Green provides a biting commentary, and while I don't necessarily agree with every assessment, she underscores some critical questions that all designers should be asking themselves, especially in the West.  In particular:

1.) What are the water and energy impacts of each potential system you might use?
In the West, if not everywhere, you have to consider these impacts as paramount concerns.  Many of the companies are investigating the impact of their components, and taking strides to improve the manufacturing cycle, but does the installation and operation of that system present an unnecessary water or energy profile?  Does it require too much water to keep the plants alive?  If so, is it really worth it?  Which leads to perhaps the underlying issue all designers must consider before specifying a green wall system . . .

2.)  Does this system accomplish something that might otherwise be unattainable? 
At its core, this question is really asking, does this system potentially provide a benefit or trade-off that might justify its use of precious resources?  The benefits of green wall systems are varied, but the primary benefit in my eyes is the opportunity to vegetate a space or surface that could not be vegetated in a traditional way, potentially introducing benefits such as visual relief, cooling, and habitat to places where limited open space has prevented traditional vegetation strategies.  As such, green walls in densely urban areas present an opportunity to bring back a piece of nature and greenery in places heavily impacted by development.   The bigger question remaining in the West, though, is whether our development conditions really warrant a green wall intervention.  As dense as cities like Los Angeles are, the by-product of low-profile, sprawling development is that there is a lot of space waiting to be reconfigured and replanted.  Designers need to evaluate each individual project and condition to determine whether a system is extending the benefits of traditional planting strategies by adding an additional niche for vegetation to thrive within, or is it simply providing an architectural folly.  Are you using a metal frame to do the job of a shrub or tree, (and if so, why are you reinventing the wheel?), or, are you creating a healthy foothold for vegetation where previously it was not considered possible? 

Other potential considerations include cost, both initial and long-term.  And in this arena, I disagree with Green somewhat.  While I wholeheartedly support Green's point that school gardening programs should be focused on reconnecting kids to the soil (and that ground-plane, soil-based gardening has a much larger positive ecological impact than any green wall system.), Woolly Pocket's program offers a cost-effective option for cash-strapped agencies who may not be able to afford the demolition costs (both financial and physical loss of space) for a traditional school garden.  It offers a foot in the door, so to speak, or, a vertical equivalent of a container garden to begin reengaging kids with the natural world.  It is not perfect or ideal, but it just may accomplish something that was otherwise not achievable. 

As any good skeptic and critic does, Green tries to remove the seductive draw of a fad and highlights the core issues that should inform the selection of any component in the landscape, green wall system or not.  Selection needs to be based on competent, informed judgement and critical evaluation.  April Philips references the same issues in her blog post.  Noting a recent LinkedIn discussion on the issue, she quotes Dean Hill, ASLA, CGP from greenscreen:
 “As designers, WE are responsible for matching the plant selection, irrigation design and maintenance commitments within the right system and intended use. In addition, I think that it is our responsibility to manage the client’s expectations. Interested clients might see pretty pictures and think that they’ve got to have one, but we need to take the opportunities to educate them so that their expectations will be met, especially with green wall systems (facade and living).”
Using and adapting green wall systems in the West is an ongoing process that requires us to consider our larger impacts, and use green wall systems because they are right for a particular situation, not simply because they are popular.  However, like all good design, effective selection of green wall components can create installations that are contextually sensitive, beautiful, and functionally adept.

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