The urban greenprint: biomimicry applied to a city

Seattle forest and buildings
CC BY 2.0 Flickr

By Alexandra Ramsden and Jennifer Barnes

Take a moment. Scrunch your eyes closed and imagine your ideal city. What do you want your city to look like in 50 years? Are you conjuring up images of tree-lined, pedestrian-friendly street-scapes enlivened with the sounds of kids, birds and restored streams? Are there more bikes than cars, is the air clean, and is food being grown nearby? In our experience, most people we ask imagine a healthy ecosystem as being part of an ideal, vibrant community. The question is--how do we get there?

We are fortunate in the Pacific Northwest. We live in a beautiful region where environmental issues are given priority. We know, however, that issues such as polluted runoff, loss of biodiversity and carbon emissions continue to threaten our region. Although many promising initiatives are being undertaken to manage these issues, we must recognize two critical facts:

1) Cities need to be addressed in solving these problems. Cities are not going anywhere - right now, more than 60% of the area projected to be urban in 2030 has yet to be built (Cities and Biodiveristy Outlook - October 2012).
2) Simply integrating natural elements into urban environments may not be enough.

Queue Biomimicry. Nature has been discovering solutions to these issues for 3.8 billion years. Nature manages water flows, filters air and maintains healthy biodiversity in a way that is conducive to life itself. That’s an incredible data bank of research and development. Doesn’t it make sense to learn from it?

The Urban Greenprint, an effort which sprouted out of our local Biomimicry Puget Sound network, is a methodology which does just that. It looks to nature to unveil solutions, not yet discovered, for the environmental issues impacting our urban centers. Every city was once a healthy ecosystem before human development impacted its balance. The goal of the Urban Greenprint is not to recreate that ecosystem but instead to understand how the predevelopment ecosystem functioned, and then ask how our urban structures and spaces can restore those same functions. How can our structures and roads provide healthy habitat? How can our rooftops evaporate or collect rainwater like the tree canopy once did? How can our building materials clean the air, sequestering and storing carbon like trees and wetlands?

Our application of this process to Seattle uncovered some surprises. One that shook us up was the fact that the current urban forest in Seattle sequesters nearly the same amount of CO2 that the predevelopment old growth forest sequestered! Although older trees store significant amounts of carbon, these trees do not continue to sequester at the rates they did when they were younger. Older trees grow more slowly, sequestering less, and CO2 is emitted by dying trees and detritus, thereby creating more of a CO2 balance than a CO2 sponge. It’s clear that the sequestration number is irrelevant if emissions are exponentially greater. Seattle’s urban forest sequesters only 2% of the City’s annual emissions (Green Cities Research Alliance report, “Seattle’s Forest Ecosystem Values”).

graph of tree co2 sequestration © Urban Greenprint

What does this tell us? As critical as our urban forest is, and as many benefits as it provides, we must think seriously about what else we can do for longer term storage of carbon. By learning how nature deals with this dilemma, several fascinating teachers rise to the surface. The natural models of salpa aspera, seashells and saguaro cacti fix carbon molecules in solid media where they are stored for a very long time.

Can we design building materials that, like shells, absorb CO2 from their surroundings and when saturated, simply continue to act as building materials, holding on to the carbon long term? And, once the building is demolished, the material could be crumbled into sand, continuing to store the carbon, only in a different, inert, harmless form? Recent advances in CO2-storing concrete make this feel achievable, and the Urban Greenprint is galvanizing support for research in this area.

In addition to our work in the CO2 arena, the Urban Greenprint is gaining traction on several other issues such as Seattle’s stormwater mitigation troubles. A second surprise in our Seattle research was the discovery that, prior to urban development, 50% of rainfall was evapotranspirated back into the atmosphere before it ever hit the ground. With the goal of decreasing polluted runoff, project proposals are underway to increase evaporation, including proposals to emphasize evaporation in Seattle’s Green Factor.

Just as every person has a unique fingerprint, every place has a unique Greenprint, or lessons to learn from nature, unique to that place. Biomimicry helps us find new (old) ways to solve environmental issues, and the Urban Greenprint provides a way to apply those ideas to create the cities we dream of.

Alexandra Ramsden, the director of sustainability at Rushing, a Seattle-based sustainability consulting and mechanical and electrical engineering firm. Jennifer Barnes is an architect at the sustainability consulting and regenerative design firm, 55-5 Consulting. Together, Alexandra and Jennifer co-founded Biomimicry Puget Sound.

Learn more at the Biomimicry Education Summit and Global Conference in Boston, MA this weekend, June 21-23 or join the Twitter conversation at #biomimicry2013. TreeHugger is a media partner of this year's event.

The urban greenprint: biomimicry applied to a city
How can our cities function like healthy ecosystems?