The Urban Sequoia NOW model imagined by Skidmore, Owings & Merrill (SOM) poses the question of whether buildings can act like trees: capturing carbon, purifying the air and restoring the environment? Urban Sequoia is based on the central premise that the built environment can absorb carbon, evolving beyond the idea of carbon neutrality to carbon negative and create regenerative cities worldwide. It uses the most advanced materials to transform buildings from being part of the carbon problem into the solution. SOM envisages “forests” of Urban Sequoias that sequester and exchange carbon to construct a resilient urban environment and change the course of climate change.
Close-up view of SOM's Urban Sequoia NOW
By taking a holistic approach optimizing building design, minimizing materials, integrating biomaterials, advanced biomass and carbon capture technologies, SOM observes that Urban Sequoia achieves significantly greater carbon reductions than when these strategies are applied independently. It consciously integrates materials and technologies that are either available now or emerging from advanced research and will be ready very soon, integrating them in ways not done before in the built environment. Some, such as Direct Air Capture, have not been used in the building industry before, while others, like algae and biobricks, have not been used at scale. I speak with Mina Hasman, Senior Associate Principal and Sustainability Lead at SOM, about how Urban Sequoia aims to be a showcase of what is possible and how much impact can be achieved when these technologies and systems are integrated into buildings worldwide.
What are the expected numerical outcomes and performance numbers that the sustainability programs of the project provide? How much carbon can be saved? What are the ways that this project has incorporated to achieve this?
The Urban Sequoia would start sequestering carbon from day one. The overall reduction in carbon emissions would actually begin during the construction process. Our goal is to successfully leverage the most progressive or emerging techniques, reducing carbon emissions from construction by about 95% (the remaining 5 % is due to the current supply chain) by entirely decarbonizing construction methods and materials, including fabrication, as much as possible. Once the prototype is built, it would then begin absorbing carbon, surpass net zero very quickly, and become carbon negative. About 10 years into its life, the building could absorb around 80 % of the amount of carbon emitted by a typical building. That number could grow to about 200 % after 25 years, and more than 400 % after 50 years.
Is it possible to retrofit existing buildings with Urban Sequoia’s technologies?
Every building type and scale will require a specific response, but the system is adaptable and can offer a solution unique to each context and will draw on the local climate and locally available resources. In an existing single family house, we would maximize passive design strategies of natural cross-ventilation, daylight and solar shading to firstly reduce the energy demand of the building as much as possible. If feasible for the building fabric and context, we would then explore the integration of renewable energy technologies such as solar panels or solar thermal collectors to specifically serve hot water demand, which would be typically high in a house. We would also study the parts of the building that need upgrading and use biobrick or hempcrete. We would additionally investigate the integration of carbon capture and storage in existing ventilation units where the air would naturally flow. At last, we would also bring nature into the building both as planting and potentially on the roof and the walls to enable carbon capture through natural means.
City view of Urban Sequoia
How realistic are your claims that the façades could turn a building into a biofuel source that powers heating systems, cars and airplanes, and captured carbon and biomass can be used to produce biomaterials for roads, pavement and pipes?
Algae is already used in some aviation biofuels. There is potential for much wider use of the by-products of an algae façade as food supplements and/or pharmaceutical products, fertilizers or cleaning products. As part of the new carbon economy, these by-products could be fed back into a district-wide or ideally a city-wide network where these new “resources” could be shared and exchanged between buildings and industries.
You developed Urban Sequoia to be adaptable to any city in the world, to buildings of all sizes and types. How do you envision the Urban Sequoia concept being applied in Asia? How would the buildings there be distinct from those built in the West?
Our vision is for a system that can be adapted to any climate in every part of the world. These buildings could become the engine for a new carbon economy: carbon could be traded as a new currency and create a circular economy, bringing a new potential stream of income for cities as they grow. By applying these strategies in cities across the world, every building, at any scale, can become a part of the solution.
Do you anticipate entire cities filled with Urban Sequoias being built across the globe? Do you believe that Urban Sequoia can serve as a model for sustainable practices for other buildings around the world, impact policy and change industry standards?
This wouldn’t be the first time SOM has brought together existing and emerging technologies in a building. With Lever House in the 1950s, for example, the curtain wall we created was ahead of its time, and it changed architecture around the world. Our Timber Tower research started in 2013 is contributing significantly to the global design community to advance on timber and hybrid construction and building design. Throughout our more than 85-year history, SOM has been ahead of the curve in the science of building. Our goal is to push all this new technology forward and help change the world of architecture again.
