The conversation around embodied carbon has gained incredible momentum in recent years. With new buildings now producing less operational carbon, the impact of embodied carbon has become a greater part of the overall sustainability picture – a shift that is reflected in the ambitious targets set by the RIBA, LETI and many others.

 

This presents a design challenge for tall buildings in particular; they typically require more structure, have deeper basements and a larger surface area (and therefore more façade) per square metre than low-rise buildings. As an essential part of our urban fabric, it’s clear that future tall buildings need to do more, using less. But how can this be done? 

 

At Gensler, we firmly believe that low embodied carbon design is the future of architecture – as a large, global architecture and design firm, we have a wealth of projects, experience, and original research to draw upon to push the boundaries with low embodied carbon design. Here are three ways we’ve been putting that knowledge into practice. 

 

In London, there’s almost always something that can be retained on any site. Even if we can’t repurpose a whole building or its superstructure, we can usually reuse elements of its substructure or basement, and there are almost always materials from existing structures that can be creatively integrated into any new proposal. 

 

Cargo in Canary Wharf is a good example of this. We radically transformed this dated office building into a new ‘front door’ for Canary Wharf through a vibrant new mixed-use ground floor experience. This bold intervention in the base of the building meant that the upper levels could be largely retained with only minor updates. 

 

Structural elements like large trusses and beams have a high carbon cost – reducing structural spans can make a huge difference to the embodied carbon of a tall building. Understanding future tenants and how spaces will be occupied is vital to optimising layouts for minimised structural spans, whist planning for future flexibility. At Gensler, we’ve found that around 25 per cent of the embodied carbon in a typical office building is a result of the basement and foundations. Minimising new basement construction can not only reduce embodied carbon but decrease construction costs and improve speed to market too.

 

The key here is to ensure that these principles are part of the design from the very beginning.  For a project with Landsec in London, we started with a focus on a low carbon structural layout from day one. This enabled us to achieve the complex form of the building in a highly efficient way, aiming to achieve LETI’s 2030 embodied carbon target of 350kgCO2e/m2. 

 

It’s important to use renewable and lower carbon materials wherever possible. Timber is a structural material that does not require the energy-intensive production processes of steel or concrete. It also has the advantage of storing carbon as it grows. While it’s not possible to substitute all structure for timber in tall buildings, it’s worth considering CLT floor slabs as an alternative to concrete.

 

For Gensler’s London office, in addition to working with an existing building, we used CLT wherever we could to lower the carbon impact of new construction. Not only did this serve a valuable environmental function but it also contributed to the unique aesthetic of the space.

 

Low embodied carbon design is the future of architecture. This will bring with it its own challenges but also opportunities to think differently about how we can construct tall buildings for a more sustainable future.