On November 11th, during the 2021 United Nations Climate Change Conference, or COP26, Skidmore, Owings & Merrill (SOM) unveiled their proposal for Urban Sequoia, a conceptual network of buildings that absorb the carbon in their surrounding atmosphere.
Efforts in reducing the carbon impact of construction processes have drawn attention for obvious reasons, as the building sector is responsible for 40 percent of global carbon emissions. Mostly, these attempts resulted in minimizing carbon emissions during the initiation, design, and construction phases.
However, if successful, the Urban Sequoia Project can decrease this amount at a precedent rate even after the completion of construction, according to a press release. The ultimate design is an outcome of integrating previous solutions in green building, including minimizing materials, carbon capture technologies, use of biomaterials, and optimizing design.
Reducing carbon with constructions
This carbon reduction occurs mainly due to two reasons. The material used in the construction of the buildings includes bio-brick, hempcrete, timber, and biocrete, which consume far less carbon than conventional materials such as steel and concrete. But the result is not solely carbon-neutral constructions. What makes these buildings even more eco-friendly is the carbon absorption that occurs after the buildings are put into use, which means the buildings are not part of the problems but might be the solution.
SOM claims the concept of this proposal goes beyond achieving net zero, as these buildings remove carbon through an alternative approach to design. They took the first step with a prototype, a high-rise building, to examine the effectiveness of the solution. While lowering carbon emissions by consuming nature-based materials, the prototype absorbs 1,000 tons of carbon annually, equal to 48,500 trees. This results in the removal of carbon up to three times more than what took for the construction. Carbon absorption occurs for the production of algae and biomass, carbon-sequestering materials, and finally, because of the air capturing feature of the buildings that filters CO2 through the stack effect.
The company’s ultimate aim is not a single high-rise or even multiple complexes, but to develop the concept on a broader scale, perhaps in cities. The concept is about forests because of the limited effect of one building, just as of one tree. Buildings with various functions, from schools, family homes, hospitals, to high-rises, can be constructed this way. To some extent, the idea is about making cities perform as forests.
"The time has passed to talk about neutrality. Our proposal for Urban Sequoia – and ultimately entire ‘forests’ of Sequoias – makes buildings, and therefore our cities, part of the solution by designing them to sequester carbon, effectively changing the course of climate change," says Chris Cooper, SOM Partner.