Growth Spurt

Growth Spurt

A footbridge at Lake Constance near Stuttgart, Germany, is supported by willow trees whose trunks and branches have been lashed together.
Courtesy Ferdinand Ludwig

As building technology races ahead, science propels it to help meet new and ever-changing standards. In the nineteenth and twentieth centuries, the breakneck tempo of progress was fueled largely by physics and chemistry, delivering a host of tools to the architect, from reinforced concrete and steel frame construction to PVC and low-emissivity glass. Today, it’s biology, as promising technologies are emerging from nature and involve stepping beyond mimicry to literally harnessing living organisms and systems to build ecologically. Le Corbusier’s steel and glass “machine for living in” may soon give way to a “living machine” or, as Salvador Dalí wrote of the future of architecture in 1933, “It will be soft and hairy.”

The increased urgency to lower the negative environmental impact of architecture is difficult to overstate. The life cycle of buildings is responsible for roughly half of CO2 emissions worldwide, a proportion that grows as urbanization intensifies, with the majority of the world living in cities since 2008. The resulting natural resource scarcity, pollution, and decreasing biodiversity threaten both social stability and long-term environmental health. In short, current practices pose tremendous risks for the future, and approaches once thought impractical or radical may illuminate the way forward.

The research among academics and practitioners into biology-driven design is farther along than one would expect. And the issues raised are challenging and range far—from radically rethinking the time frame it requires to grow structure to acknowledging that architects and scientists do not even use the same language and may need to invent a new one to communicate.

The footbridge is made out of 80 bundled struts, each containing 12 or more plants each. These support a 22 meter, steel-grate walkway and handrail (left). Trees thicken around points where the handrail intersects them, adding strength (right).

One recent project that creatively and presciently addresses these issues is the footbridge at Lake Constance near the University of Stuttgart in Germany. This design incorporates engineering with living plants to integrate architecture with its immediate environment. The designers Ferdinand Ludwig, Oliver Storz and Hannes Schwertfeger call this approach Baubotanik, which they developed as part of their PhD research at the Institute of Modern Architektur und Design IGMA at the University of Stuttgart. The bridge blends research and application and takes a critical stance: by embracing what the architects call an “aesthetic of uncertainty” in its use of continually changing, living materials, Baubotanik is meant to undermine the implicit claims of traditional architecture to be stable, permanent, and self-sufficient.

Baubotanik utilizes trees as load-bearing systems and harnesses what the designers call their “constructive intelligence,” as branches naturally strengthen in response to stress or increased loads. At the same time, the practice exposes designers to the bio-dynamics and unpredictability of natural growth. Built on a low-lying wetland into which a classical support structure would sink, the footbridge is constructed from thickly planted willow, a tree with uniquely aggressive, strong and deep roots, known for piercing drain pipes ten or more feet underground. Robust like a tremendous weed, willows grow rapidly, can be readily bred from small cuttings and can be grown crosswise to form a stable meshwork.

Clockwise from top: The footbridge, still strong, in winter; Young trees will grow to support the hand rail; detail of trees surrounding handrail; view of the footbridge.

The architects believe that this process, by forcing the builder to navigate the conflicts and lack of control inherent in the materials, creates a form of architecture characterized by serendipity, learning and risk (a fungal disease can kill several trees and destabilize a structure). The process also lengthens construction timeframes with plants needing to be almost a year old to be useful, and plants support limited weight. The tallest test structure is a slim tower 30 feet in height with a 90-square-foot footprint and requires 100 small trees.

Baubotanik yields two long-term environmental benefits: an incentive for the structure’s owner to maintain healthy conditions for the trees, such as soil quality, and the creation of habitats for several species. In effect, structures built with trees can work like coral reefs, providing footholds for small but rich ecosystems including birds and insects. Several Baubotanik test structures have been completed in Germany to date, and the technique, which involves a complex procedure of grafting and stressing trees to bend and strengthen them, is now a focus of study at the University of Stuttgart. The approach is also being considered by the non-profit LiloRann as a means to build green walls to halt desertification in North Gujarat, India.


Close-up view of BioConcrete showing a small hole and crack (left). Bacteria have repaired both by secreting limestone, a process they perform naturally (right).
Courtesy Henk Jonkers

A similar but potentially more far-reaching development is the creation of self-healing BioConcrete, which is essentially traditional concrete infused with specialized bacteria and nutrients. The material’s “infection” is harmless to humans and has the effect of filling eventual cracks in the concrete through a natural process called biomineralization. The bacteria secrete limestone that effectively fills any fissure that appears from normal wear and tear. After proving the concept many times in the laboratory, Henk Jonkers of the University of Technology at Delft, The Netherlands, is now focused on testing to find precise conditions under which this new technology can be reliably and safely applied. Jonkers’ objective is “to use bio-based materials and processes for civil engineering practices in order to reduce environmental pressure, acknowledging that in nature no waste is produced as everything is continuously recycled.”

The positive impact of BioConcrete is potentially vast, as it can lengthen the lifespan of concrete while lowering the cost of its maintenance. In fact, a full five percent of human-made carbon emissions arise from the energy-intensive process of making billions of tons of concrete every year, so any marginal improvement in its performance can yield far-reaching effects. If widely applied, BioConcrete may become the 21st century analog to re-enforced concrete, designed for better ecological performance in the long term by integrating a symbiotic and invisible living process into architecture.

A third project that integrates living systems is HOK/Vanderweil’s visionary Process Zero proposal, a retrofit solution for a hulking, 1960’s era General Services Administration (GSA) building in downtown Los Angeles. The proposal won Metropolis magazine’s Next Generation Design Competition in 2010, which called for a zero-footprint retrofit. The design reduces the structure’s overall energy demand by 84% while generating the remaining 16% on-site with natural algae and photovoltaic film. The principle strategy guiding HOK’s team, led by Sean Quinn, was to consider the “building as a cell” interdependent with its environment. From this point of view the team aimed to choreograph natural systems with mechanical processes to achieve its goals.

Spanish architect Alberto T. Estévez, who directs a research group on Genetic Architecture at the Universitat Internacional de Catalunya, imagines genetically-altered bioluminescent trees replacing streetlights in Barcelona.
Courtesy Alberto Estevez, Universitat Internacional de Catalunya

“We explored the inherent abilities of algae to purify air and water, and then investigated the means to harness energy from it,” explains Quinn. This is achieved through bioreactors that convert oils from algae into energy, a technology already in use on several university campuses. The system would cover 25,000 square feet of the building’s envelope with a network of tubing, capturing sunlight and naturally absorbing CO2 from the air. Coupled with this system, more than 60,000 square feet of photovoltaic film would cover parts of the roof and facade for both shading and energy collection.

To develop this unique bio-integrated solution, Quinn and his team consulted with biologist Thomas Nassif to understand the potential of growing algae as they envisioned, and architecture and engineering professor Soolyeon Cho to calculate potential energy generation. Quinn notes: “These interactions might have been unusual a few years ago, but it’s more common now and absolutely essential to engage outside experts to develop environmental solutions. Their role, as it expands in the coming years, will be invaluable.”

HOK and Vanderweil’s Process Zero project is retrofitting a GSA building in Los Angeles with natural algae and photovoltaic film to reduce energy consumption and self-generate all required power.
Courtesy HOK / Vanderweil

To facilitate cross-pollination among disciplines, the Synthetic Aesthetics project was launched this year by the University of Edinburgh and Stanford University with funding from the National Science Foundation. It formed six scientist-designer teams from around the world to “help with the work of designing, understanding and building the living world.” Each team is developing a research goal based on shared interests and points of connection between issues in participants’ respective fields. In one example, the architect and Columbia University professor David Benjamin and postdoctoral researcher Fernan Federici from the University of Cambridge are exploring how to use biological systems as design tools that might augment or replace conventional methods. Specifically, they are investigating ways to fabricate synthetic composites by creating novel morphogenetic mechanisms in bacteria and plants, a process that contrasts with digital fabrication and CNC machines with fixed and pre-determined physical outputs. The Synthetic Aesthetics project takes the position that synthetic biology will inevitably be critically important to numerous disciplines—from art to urban planning, and that cooperation among fields of study at this early stage is essential to enable the very best inclusive and responsive technology development.

In the award-winning project, Urbaneering Brooklyn, Terreform1 reimagines the city as a network of ecologically active pathways, providing and recycling all vital resources to support the population.
Courtesy Terreform1

Pioneering in this new space is the Brooklyn-based One Lab, recently launched by Parsons professor and architect Maria Aiolova. The two-week program offers instruction to students, architects, biologists, urbanists, and artists interested in collaborating across disciplines. Activities focus on harnessing living matter for design and range from instruction in synthetic biology and the basics of genetic engineering, to computation and parametric design. The program’s goal is to encourage, cultivate, and achieve synergies that would otherwise be missed because practitioners and educators are often siloed in their particular areas of expertise. Joachim’s firm Terreform1 recently won a Victor Papanek Social Design Award sponsored by the Museum of Arts and Design and the University of Applied Arts in Vienna for their Urbaneering Brooklyn proposal, which imagines Downtown Brooklyn 100 years in the future as a integrated organism.

Taken together, these design experiments and collaborations anticipate exciting developments in architectural education, such as integrating curricula with basic biology courses and lab work. The new crop of architects may need to know their way around a microscope if they mean to create a next generation of responsive building materials or to find optimal methods for integrating built and natural environments. And they’ll need to adopt a new aesthetic outlook by relinquishing the control traditionally so fundamental to the practice and by integrating the uncertainty of biology. Such change won’t be easy: research has shown that scientists and designers encounter obstacles reconciling differences in methodology, expectations of timeframe, and even language. Yet, the life sciences offer a link to those natural processes operating with astoundingly efficient economies of energy and materials—all powered by the sun. In the age of climate crisis and with increasing demands on building performance, collaborations that learn from and harness the living world will multiply, and may even remake the world a little more like Dalí imagined it.