The visionary concept of a carbon-absorbing building may soon be a buildable reality, based on a reductive approach to construction—rather than the typical additive one, which builds a structure first and adds to it—plus materials that sap carbon from the surroundings, and low embodied carbon materials to regenerate carbon-dense environments.
After a year of research since COP26, where Skidmore, Owings & Merrill (SOM) first presented the concept, the firm has refined its vision into something it claims to be buildable right away. The firm’s findings were presented at COP27, the 2022 UN Climate Change Conference in Sharm El-Sheikh, Egypt.
The design updates SOM’s 2021 high-rise prototype to a building capable of reducing upfront embodied carbon by 70 per cent—from construction alone—when compared to a typical high-rise. The project is titled Urban Sequoia NOW, alluding to how the building would act like the tallest trees of the world and that it is already possible to build.
In the first five years of the building’s life, it would reach a 100 per cent reduction in whole life carbon, achieving net zero. Over an extended, 100-year lifespan, an Urban Sequoia building would absorb more than 300 percent of the amount of carbon emitted in its construction and operations.
Rather than take the typical additive construction approach, in which a structure is built, followed by the facade, the MEP and other building systems, and the interior fit-out—all of which add carbon to the atmosphere—builders would combine construction into one, streamlined process. In this reductive approach, every part of the building would serve multiple purposes. The design is an inversion: all the systems that are typically hidden in ceilings, like air ducts and other MEP equipment, would be consolidated or even eliminated. SOM’s new approach optimizes the floor slabs to include those systems within the floors and raises the ceiling heights simply by removing the ceilings altogether, significantly decreasing material use.
Air would flow into underfloor ventilation openings, situated between the slab and a timber floor finish, as well as sky gardens doubling as amenities and large air capture zones. Cool air would move into these gardens and enter open cavities in the building’s core, where the stack effect would bring air up through direct air capture technology embedded within the building’s core and roof. The captured carbon would then be stored and available for use in various industrial applications, completing the carbon cycle and forming the basis of a new carbon-removal economy.
Urban Sequoia NOW is applicable to any building type, at any scale, and in any location. Each building type uses carbon-sequestering materials, like timber and bio-concrete, to reduce embodied carbon emissions, and advanced technologies such as energy-generating solar glass to lower operational carbon emissions. The idea across the board is to regenerate the environment in the world’s densest places, where carbon emissions are highest, and to do so with a timeless design that has the flexibility to be adapted over the course of a century. Bringing this idea from concept to reality will create a network of Urban Sequoia buildings across the world that absorb carbon, every year, for the next 100 years or more.
“Urban Sequoia is a systems approach, a philosophy,” said SOM sustainability director Mina Hasman. “It is a way of thinking about cities as ecologies, as living and breathing systems that can be reconfigured to achieve dramatic reductions in whole life carbon, reframing the built environment as a solution for the climate crisis.”