Sunday, 30 June 2013

No trees please.

For some reason, my posts about trees on buildings have had more attention than any other posts.  My core message has been that architects are putting trees into renderings of proposed buildings, in a disingenuous attempt to divert attention from the lack of any real progress towards truly sustainable new buildings - towards the more considered matrix of urban development that heals the environment in a true, complex way.

But I suspect most people, especially the architects, are ever more hopeful, and therefore my attempt to be balanced by commenting more or less positively on WOHA's Singaposre Park Royal as an actual built example, is possibly my most viewed blog.  Like other hopefulls, I also seized on the hoisting of the first tree into place on Milan's Bosco Verticale with some enthusiasm. Time for a reality check.

The original author of 'Can we please stop drawing trees on top of skyscrapers?' Tim De Chant is himself quite obviously a tree lover and advocate for reforrestation.  It is worth revisiting his rather more extended examination of trees on buildings, in that wider framework of marginal value of ecological rehabilitation.  In 'More reasons to stop putting trees on skyscrapers' back in April, he sets up a simple comparison between the Bosco Verticale and a 'real' forest, both in terms of monetary cost and ecological outcomes.  In his simple comparison, he uses figures from restoring woodlands in the US and from the intensely human modified countryside of Italy.  He even uses urban parkland, not unexpectedly Central Park in NY.

There is no mistaking his conclusions.  There are a couple of orders of magnitude difference between the effort required to achieve nominal tree presence on buildings as opposed to that spent on resuscitating the region’s natural habitat.  He dismisses the claim that trees on buildings are worth it for the inspiration: 
I see them as a distraction and potential liability—what if the Bosco Verticale becomes a brown eyesore, turning people off to his larger vision? I’d love it if Bosco Verticale and other proposed arboreal skyscrapers were sustainable and successful.³ Who wouldn’t want to live in a city full of tree towers? But I just can’t make a case for it. Plant physiology tells me that the trees, if they do survive, will require constant and costly maintenance throughout their short, brutal lives. Finance tells me that the money required to afforest a building would be more effectively used for restoration and preservation. And my gut tells me there are more equitable ways to give people trees, not just to those who can afford it.
I think he is right.  Which is not to say there is no ecologically and financially sound model for maintaining plant communities in cities.  De Chant emphasizes urban parks and street trees.  There are the 'green fingers' of managed drainage systems, doing triple or more duty as active recreation space and channels of cooling breezes in summer (Zurich in Switzerland is the most cited example).  At building level, there seems little problem in growing low scale vegetation on a modest amount of soil on horizontal roofs.  Not only can one realistically aspire to produce some edible crops, but the overall 'capacitive insulation' value of the roof can be demonstrated to have energy efficiency benefits.  The latter can be achieved even where we acknowledge that a lot of roofs have to be low water landscapes.  And even on high rise, large wintergardens can materially affect well being, partly trough measurable effects on air quality of conditioned interiors.

Just not gratuitous photoshopped trees, please.

Read More reasons to stop putting trees on skyscrapers on Per Square Mile.  The extended essay is supported by references.


Anonymous said...

I couldn’t agree more with De Chant’s concerns about Bosco Vertical, and somehow managed to exaggerate them too. What if the building starts killing people when branches fall from 100m in high winds, or if it’s doomed to become like Strathfield plaza driving its inhabitants mad every evening thanks to unbearably loud birds?

I agree it seems a lot more feasible and effective to preserve and/or re-green the surrounding urban environment. Paddington Reservoir Gardens is a successful local example of a lower maintenance alternative with better social and environmental effects; an older example still is Wynyard Park, dating back to the 30’s!

Jason Pomeroy offers an interesting exploration of the social and environmental implications of integrating greenery across a vertical urban network of public, semi public and private spaces. His theory derives from exploring Nolli’s maps in three dimensions, integrating public ‘skycourts’ or ‘skygardens’ across a multi-level urban infrastructure, citing examples like Holl’s Linked Hybrid and OMA’s The Interlace.

2) “Living Architecture: Green roofs and walls” by Graeme Hopkins and Christine Goodwin (provides great Australian examples as well as regional plant lists)
3) “The Skycourt and Skygarden: Greening the Urban Habitat” by Jason pomeroy.

Anonymous said...

I too agree that “green” architecture has become literal in a sense that many are quick to immediately associate the use of planting or trees in a high rise building with success through sustainability. It emphasises our roles as aspiring architects in this topic as it goes deeper than the visual renderings we provide. To viewers, these architectural renders may not give much thought beyond the aesthetics and charming relief within block cities suggested by the incorporation of trees on towers. As a profound source of inspiration, trees and at a smaller scale, living walls in buildings must be followed through with the results as examples of the capabilities of future sustainable buildings.

Locally, this is exemplified within the recent Sydney development of Central Park where green walls encapsulate the apartment blocks while using an on-site water ­recycling plant, tri-generation power station and central thermal plant. Each building in Central Park is proposed to achieve a minimum five green star rating and will have its own water recycling factory operated by the Water Factory Company. Central Park appears to have become iconic for Sydneysiders through its large role in promoting an almost self-sustaining and environmentally conscious design.

However, I believe that it is also important as designers to acknowledge that these “green” facades may in fact be “for the rich and no one else” as described by Tim de Chant. Living walls can often glamourise and perhaps hide the truths about the environmental performance of buildings. In reality, they may challenge sustainability through the high costs of maintenance and engineering to compensate for the lack of deep soil planting. Perhaps without looking at the financial side of Central Park, Sydney, in the coming years we may not be able to completely underline it as sustainable. Rather, the costs can be used more effectively in the site specific design that responds to a buildings unique climate and preserving or maintaining the natural hotspots that we already have. Thus, it is important as designers to view beyond the illusions of architectural renderings and understand the implications as well as the potential of practicality.

Justin Buckwell said...

With reference to Tim De Chant and his comparison of urban vs ‘real forest’, his argument appears to be a financial one. He points out the expense of extra materials required to engineer a structure to support the proposed planting, estimated at over 8000 times more costly than the reforestation of a region of the same size. And that doesn’t take into account the ongoing maintenance.
I agree that’s quite a convincing argument if you are looking at the increased biodiversity only, and with a clinical accountant’s eye.
My question is, what about the social and psychological benefits of this approach to forestation for commuters passing by Bosco Verticale each day. As well as the community that will be living along side of this development and its residents?
By the implementation of urban planting, research points to social and psychological improvements of communities.
If the argument is one of money, I am critical of Tim De Chants comparison as simplistic in that he doesn’t take into account financial benefits of improved communities, factors such as; a decrease in social services by improved neighbourhoods and health, improved revenue from an increase in office worker productivity, increase in property prices in neighbouring communities, savings in energy by shading. None these account as a long-term financial benefits in Tim De Chants spreadsheet and over a long period would have significant financial implication, which counter his estimated figures.

Research on the ‘Benefits of Urban Trees’ has been compiled from many sources by the non-profit organisation, Keep Indianapolis Beautiful, Inc . It can be downloaded from Harvard University.

1. Prow, Tina., “The Power of Trees”, Human Environmental Research Laboratory at University of Illinois.
2. De Chants, Tim “More reasons to stop putting trees on skyscrapers”
3. Benefits of Urban Trees

Unknown said...

Hello, thanks for the article. I wonder what you think about the integration of trees and buildings, considering the possibility of growing trees without soil, which we are experimenting with. at

Daan van Geijlswijk

Steve King said...

I looked at your blog with great interest. Visually baring the root system of tree in the way that you are doing has little or no utility for the problems in which I am engaged, but you seem to be engaged in a wonderfully complex art project with a very interesting commentary.

In the context of integration of plant material with buildings, the area of greatest interest is replacing soils with lightweight growing media. It is closest to the general field of hydroponics, but without any pressing reasons to do away with the growing media altogether.

You have prompted me to perhaps return to the general thread of those posts as soon as I have a little more time.