Can High-Rise Buildings Be Carbon-Negative?

For the past couple weeks, world leaders have gathered at the UN’s COP26 conference in Glasgow to establish ambitious new targets for cutting carbon emissions as the climate crisis intensifies. While many of the discussions involve finding alternatives for burning fossil fuels, little attention has been paid toward architecture and the built environment. Considering rampant urbanization and how the building sector currently generates 40 percent of carbon emissions, architectural innovations shouldn’t be overlooked. 

One major idea comes from SOM, which unveiled a high-rise building typology that absorbs more carbon emissions than it creates. Called Urban Sequoia, the conceptual net-zero structure employs carbon-storing materials such as bio-brick, hempcrete, timber, and bio-crete that reduce the carbon impact of construction. Taking cues from rooftop gardens, the building’s facade and “gray” surfaces can be covered with biomass and algae, which captures up to 1,000 tons of carbon per year, the equivalent of 48,500 trees. This can be converted into biofuel that can power heating systems, vehicles, and industrial processes, effectively creating a “carbon-removal economy.”

“The power of this idea is how achievable it is,” SOM principal Yasemin Kologlu says. “Our proposal brings together new design ideas with nature-based solutions, emerging and current carbon absorption technologies, and integrates them in a way not done before in the built environment.”

Though Urban Sequoia can exist autonomously, SOM stresses that the concept towers should ideally root neighborhoods equipped with similar carbon-capturing technology. It’s no easy task—most buildings are highly inefficient, and decarbonizing them amounts to a tremendously complex task. Still, decarbonization is catching on as a crucial way for cities to combat climate change. The town of Ithaca, New York, recently approved a first-in-the-nation plan to decarbonize all 6,000 of its buildings by 2030, but whether or not major metropolises will implement the practice for their notoriously eco-unfriendly high-rises remains to be seen.