Buildings are a major part of the climate change problem. They require a lot of energy to build and operate, accounting for 74% of electricity consumption and a third of greenhouse gas emissions in the United States alone. Plus, before they’re even occupied, the production of building materials and the process of construction represent another major source of what’s known as embodied carbon, adding up to an estimated 11% of global carbon emissions.
The global architecture firm Skidmore, Owings & Merrill understands the environmental impact of buildings and wants to do more about it. Being in the business of designing new buildings – and adding to the problem – SOM acknowledges that architects are hardly guilt-free. “The question we asked ourselves,” says SOM partner Chris Cooper, “is how do you make a building that does more good than harm?”
Their answer, presented recently at the COP26 United Nations climate change conference, is a building that absorbs more carbon dioxide than it produces.
The concept, called Urban Sequoia, proposes a building with a physical form optimized to reduce energy requirements, coupled with building materials and systems that either sequester carbon dioxide or suck it out of the air. The towers the architects have designed to illustrate this concept have several cutting-edge elements. Wrapping the buildings are algae-filled facades that produce biofuels that can power the building. Inside, structural components made of biological materials and insulation made from hemp sequester carbon throughout the building’s lifetime. Built-in direct air capture systems pull CO2 out of the air and either store it or make it available for industrial use.
The vision is an idealized green building, based on materials and technologies that sound futuristic but already exist today. Putting them all together into a carbon-absorbing building – or better yet networks of carbon-absorbing towers – could be a way to offset the carbon footprint of the building industry, and several other industries, too.
“There’s a recognition that buildings play a major role in carbon emissions. And as architects who build lots of buildings, we play a role in that and we have the potential to help make change,” Cooper says.
One might suggest that it could be possible to reduce this impact if only we stopped building so many buildings. But with a fast-growing global population that’s expected to add another 2.5 billion people to cities by 2050, not building to accommodate humanity’s expanding magnitude is untenable. Cooper says Urban Sequoia is SOM’s attempt to start finding a better way of accommodating all that growth.
“All of this is the why [behind the project]” he says. “As architects, we’re implicated. And also we have the ability to try to create change.”
The tools to create carbon-absorbing buildings are available now, says Yasemin Kologlu, principal at SOM. Bio-based carbon sequestering materials like hempcrete are being used in a growing number of buildings in Europe, and carbon capture systems are advancing at a pace Kologlu says can be measured in years not decades.
“It’s not a hypothesis,” she says. “We just need to look beyond our building industry into other industries and leverage some of the technologies and systems that exist.”
Cooper says the next goal is to start building prototypes. “That can happen at any scale,” he says. “That can be a pavilion made of bio brick that’s absorbing carbon, that’s almost an easy solution, or it can be a tower that has direct air capture and materials that absorb carbon.”
SOM is partnering with universities and industry partners to explore ways of incorporating some of these elements into new building projects, and eventually bringing a full-scale prototype to life. That may be a ways off, but SOM is releasing the Urban Sequoia concept as a provocation and an argument that a different kind of building is possible. Cooper is hoping that fleshing out the idea will help convince architects and designers that the massive carbon footprint of their work is not inevitable.
“The discourse in the industry is how to reduce carbon,” he says. “That’s not a good enough conversation.”