http://www.inhabitat.com/2007/12/12/ar-awards-ecoboulevard-from-ecosistema-urbano/

Ecoboulevard grew from an urban design competition in Vallencas, Spain, that aimed to bring both people and greenery to the city’s main street. Ecosistema Urbano Architects brought the community’s goals to life with an innovative installation of “air trees” - lofty nursery-like extensions that meld urban and natural elements. The concept captivated the AR Awards for Emerging Architecture jury, earning the young designers a much-deserved accolade.

Ecoboulevard is shaped around recycled gasworks, allowing the project to grow from repurposed industrial materials. The “air trees” share the service of pavilion, what the designers call a “social revitalizing” space. These centers have, by way of the rooting vegetation, a cooling effect on the urban environment. The open structures can also facilitate social gatherings that require electricity - each “air tree” is equipped with solar photovoltaic to meet on-site energy needs.
The architects have gone beyond the obvious benefits of reusing materials and have considered a growing urban landscape. When the plants are established, the remains of industry can be disassembled and removed, leaving behind a flourishing greenway. This aspect, what the AR Award jury referred to as “the idea that a temporary structure could make a long-term proposition about the way a city streetscape might adapt in the context of ever-hotter urban environments,” is one of the most impressive facets of the 

http://www.inhabitat.com/2008/01/24/stunning-air-trees-only-byproducts-are-h2o-energy/

The city of Madrid soon plans to add a striking new structure that will “climatically transform” its urban architecture. Designed by Urban Ecosystems, the Air Tree pavilion is to be built from recycled materials and will be 100% energy self-sufficient. Using photovoltaic cells, the Air Tree produces a substantial amount of energy, which is then sold back to the local electric companies, the profits being used for maintenance of the structure. The second byproduct is of course oxygen - hence the name ‘Air Tree’!

We’ve written about the Madrid Air-Tree before, when the design ‘Ecoboulevard’ for industrial revitalization won the AR Awards for Spanish Architecture group Urban Ecosystems. Aside from their aesthetic appeal, the trees have a very interesting benefit for the local residents who have to suffer through hot Spanish summers. The surrounding environment near the air tree will be naturally conditioned, reducing the heat island effect found in most city centers. The air trees will be implemented city wide in the coming years. 
Furthermore, the structure, made from lightweight recycled materials, can be easily disassembled and moved to another site when needed. This feature makes the entire idea really intruding because dozens of air trees can be installed in cities around major metropolitan areas during summers. The trees will cool the surrounding environments and as a bonus generate clean electricity. If 

http://greenlineblog.com/madrids-air-tree/


In 2004, the Madrid Municipal Housing Corporation’s Residential Innovation Office (with support from the EU LIFE Program) sponsored the Eco Boulevard Competition to design an outdoor urban space in the Madrid suburb of Vallecas. The competition asked designers to imagine an outdoor space that “climatically transformed outdoor urban space.” The designs should also “improve environmental comfort, promote social exchange and be more sustainable than conventional models of growth in the city. Interestingly, this particular portion of Vallecas did not and still does not exist entirely. It is part of a major planned urban development on the outskirts of Madrid. The actual Eco Boulevard site was a strip of land roughly 500 meters long by 50 meters wide.

The winning entry was submitted by Urban Ecosystems and is loosely titled ‘The Air Tree.’ Their proposal was to create three open air pavilions in the space which would each be programmed with a different activity chosen by the users themselves. The pavilions were designed to be a “prosthesis” around which social activities, biological growth, and architectural edifice could grow. The pavilions would begin their life as nodes for activity within the new urban centres. Then, over time, as the surrounding context developed and grew, the pavilions would loose their character as node and instead become voids within the urban fabric. The structures will eventually be deconstructed and recycled.

(above) A diagram of development along the Eco Boulevard from year 0 to year 20
The pavilions or air trees themselves are designed to be lightweight, deconstructable, and self sufficient (to produce their own electrical energy). All three are designed using one rough kit of design elements that then are skinned to perform specific tasks depending on the activity taking place at that particular pavilion. Photovoltaic panels mounted to the top of each structure produce energy used to operate the air trees. Surplus electricity is sold back to the grid and the proceeds are used to help maintain the urban park.

Each air tree was also designed to condition the surrounding environment. Because the designers realized that the air trees would stand solitary for many years until the surrounding trees and vegetation grew, the designers planned for the air trees house their own plantings. Urban Ecosystems therefore placed hundreds of small trees in soil on the perimeter of the air trees. They describe the system as:

“…Simple air conditioning systems installed in the air tree. They are evapotranspirators. This is a natural way to air condition a space, not a part of commercial strategy. Rather, it creates naturally conditioned spaces between 8-10°C cooler than the surrounding streets where the residents can take active part in the public domain.”

The project is currently under construction. All three pavilions have been built and work continues on the overall masterplan for the Eco Boulevard and the remainder of the Vallecas project.

Here (below) is an animated gif showing the general concepts for the project.