Trees capture carbon, purify the air and regenerate the environment. But what if buildings could do that? Urban Sequoia is a design concept setting the stage for a new carbon-removal economy and a buildable resilient future for our cities.

Urban Sequoia – a concept for buildings in their urban context to absorb carbon at an unprecedented rate.

Chris Cooper, design partner at SOM

Buildings as a climate solution

SOM unveiled their concept, Urban Sequoia, at COP26, in Glasgow. SOM has also developed the first step towards achieving this goal on a broad scale, with their prototype for a high-rise building that can be built today.

The concept’s approach is for the built environment to be able to absorb carbon and rethink the construction of buildings and cities.

This viable approach has the potential to create a circular economy absorbing carbon and having an extensive impact. Chris Cooper, design partner at SOM, says the trajectory of climate change must be altered to go beyond net zero. “We need to take carbon out of the atmosphere through the built environment, and we have developed a design to do just that.”

A buildable prototype

Urban Sequoia merges different strands of sustainable design thinking, the latest innovations and emerging technologies, and applies them to buildings. Through an optimised holistic building design, minimised materials, the integration of biomaterials, advanced biomass and carbon capture technology, Urban Sequoia actualised more carbon reductions by applying the techniques separately.

The next phase

Since unveiling the concept, SOM has refined the architecture of the high-rise prototype and presented the next phase of the design at COP27 in Sharm El-Sheikh, Egypt, in 2022.

The process was guided by three questions, with Urban Sequoia’s latest designs having the answers:

  1. How low can we go in emitting carbon in construction – the building would reduce upfront embodied carbon by 70%.
  2. How high can we go in carbon sequestration – in the first five years of the building’s life, there will be a 100% reduction in whole-life carbon, achieving net zero.
  3. How long can we go in extending the typical building’s lifespan – over an extended century lifespan, the building would absorb more than 300% of the amount of carbon emitted in its construction and operation.

The overarching idea is to regenerate the environment in the world’s densest places – where carbon emissions are the highest – with a flexible, timeless design that can be adapted.

Construction approach

The construction process will be streamlined. In a 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, such as air ducts and other MEP equipment, would be consolidated or even eliminated altogether.

SOM’s new approach optimises the floor slabs to include these systems within the floors, and eliminates the need for suspended ceilings, which is significantly decreasing the material use.Air would flow into underfloor ventilation openings, situated between the slab and a timber floor finish.

The Urban Sequoia concept.

Sky gardens would create 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 carbon-removal economy.

Nature-based strategies

Nature-based strategies can be applied to buildings of all sizes and types, as it will use carbon-sequestering materials (such as timber and bio-concrete) to reduce embodied carbon emissions and advanced technologies such as energy-generating solar glass to lower operational carbon emissions.

Beyond net zero

The solution will allow us to move beyond net zero, delivering carbon-absorbing buildings and increasing the amount of carbon removed from the atmosphere over time.

Captured carbon can be used in various industrial applications to complete the carbon cycle and form the foundation of a new carbon-removal economy. Integrating biomass and algae, facades could turn the building into a source of biofuel powering heating systems, cars and airplanes; and a bioprotein source usable in many industries.

Cities as part of the solution

On a wider scale, the by-products of building an Urban Sequoia will help revolutionise design and maintain infrastructure. Captured carbon and biomass can be used to produce biomaterials for roads, pavements and pipes. Through the conversion of urban hardscapes into gardens and designing intense carbon-absorbing landscapes and retrofitting streets with additional carbon-capturing technology, it is possible to sequester up to 120 tons of carbon per square kilometre. It is possible to save up to 300 tons per square kilometre of carbon annually if these strategies are replicated in parks and green spaces.

Full acknowledgement and thanks go to for the information in this editorial.

Images: SOM / Miysis

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