Trees That Don’t Grow: Twenty Years of the Ecobulevar of Vallecas

THE AIR TREES OF ECOBULEVAR VALLECAS

The three air trees of Ecobulevar de Vallecas were never meant to last twenty years. When they were inaugurated in 2007, they were conceived as a provisional solution: to provide shade while the new neighbourhood’s trees grew large enough to replace them. That timeframe has now passed. The trees have grown. The structures are still standing.

To understand the project, it’s necessary to go back to the late 1990s. The Ensanche de Vallecas was one of Madrid’s largest urban development operations: over 700 hectares and 29,000 planned homes to the southeast of the capital, between the old town of Villa de Vallecas and the M-45 ring road. As in other developments of the period, streets and public spaces were built before the trees could grow enough to provide shade. For years, the central boulevard was a large open space with barely any protection from the sun.

Against this backdrop, Madrid City Council, through the Municipal Housing and Land Company (EMVS), launched a competition to intervene in one section of the boulevard. It was won by Ecosistema Urbano, the studio founded in 2000 by Belinda Tato and José Luis Vallejo, with a proposal co-financed by the European Union’s LIFE programme. Construction ran from 2004 to 2007 along a 550-by-50-metre strip.

The idea was simple: if a grove of trees takes fifteen to twenty years to grow, architecture could cover that waiting period. This gave rise to the three air trees, large metal structures conceived as a temporary prosthesis for the landscape.

Each of the three pavilions was designed with a different function. The climatic tree, located at the northern end, filters light through sixteen perimeter lobes and used a passive evapotranspiration system intended to lower the temperature by up to ten degrees compared to the surrounding area. It is the same physical principle behind the cooling effect of traditional Mediterranean and Andalusi courtyards, although the studio itself cited greenhouse industry systems as its technical reference. The media tree was designed for events and screenings, while the play tree was conceived as a space for neighbourhood gatherings. Above the three structures, a photovoltaic installation was meant to generate the energy needed to power the system and sell surplus electricity to fund its own maintenance.

The intervention also included densifying the tree planting and an asymmetric reorganisation of the road layout, reducing space allocated to traffic in favour of pedestrians. The project was recognised in 2008 and added to UN-Habitat’s best practices database. In the years that followed, it appeared recurrently in international publications and conferences as one of the best-known Spanish examples of sustainable urbanism and climate adaptation.

Twenty years on, the timeframe the project envisioned has now elapsed, but the outcome doesn’t exactly match what was imagined. The trees have grown, though not to the point of making the structures unnecessary. At the same time, the planned maintenance never took hold. Residents of the neighbourhood have reported the deterioration of the installations and the climbing plants meant to cover their interior since 2010. In 2014, a fire damaged part of the climatic tree. Ecosistema Urbano itself has acknowledged that maintenance has been one of the project’s weakest points.

However, while some of the technical systems were breaking down, the uses of the space kept growing and evolving. The media tree came to house the Nautilus children’s playground in 2018, and the play tree continues to host concerts, workshops, neighbourhood festivals and cultural activities. The pavilions’ function has changed over time; the organic use people have made of them has kept them useful and current.

This evolution has also fuelled debate around the project itself. Urban planner Ramón López de Lucio, professor of Urban Planning at ETSAM, published one of the harshest academic critiques of the Ecobulevar in 2017. Writing in the journal ZARCH, he uses it as an example of the combined failure of planning, urban design and architecture in Madrid’s public expansion areas of that period. His critique barely focuses on the structures themselves. The real problem, he argues, is the urbanism surrounding them: a boulevard with little commercial activity, few access points from the housing blocks, and a layout unable to generate urban life. In this context, he describes the air trees as «spectacular, costly and useless design trees,» incapable of correcting the shortcomings of an urban model he considers flawed from the outset.

The two decades since the inauguration make it possible to observe something that was impossible to measure in 2007. Some of the ideas most closely tied to technology have lost prominence over time and through lack of maintenance, while the spaces themselves keep adapting to the neighbourhood’s changing needs. At the same time, the project remains an international reference in publications on climate-conscious urbanism and one of the most cited examples in Spain when discussing the achievements and limits of new urban expansions.

The air trees were born with an expiry date. Their purpose was to disappear once real trees no longer made them necessary. Twenty years on, they are still there. And that, in itself, is a sign of their success, even though they were designed within an urban environment that left little room for roots.