Future of Net Zero | Free calculator leads to carbon savings and collaboration for US project

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United States


New Civil Engineer

Stakeholders in a new mixed-use development in the United States have cut embodied carbon during the project’s design phase thanks to an accessible calculation tool.

United States consultant Thornton Tomasetti has slashed embodied carbon on one of its projects by nearly 40% during the design phase. It has done so using a free-to-download carbon calculator developed by the Institution of Structural Engineers (IStructE).

The consultant worked with architects Studio Gang and master planned communities developer Howard Hughes Corporation on the mixed-use project. They harnessed the power of the carbon calculation tool to bring several different collaborators together so they could understand the effort to reduce embodied carbon.

Thornton Tomasetti structural engineering principal Tanya de Hoog says that engineers often wait until certain ideas have been set in stone before they offer solutions for carbon reduction. But she says that having the data from the calculator at an early stage allowed the project team to communicate possibilities for reducing carbon sooner with a greater resulting impact.

Thornton Tomasetti sustainability associate director Duncan Cox agrees: “It gets that engagement from all parties very early, which is one of the biggest battles we have. It sort of demystifies the process of doing embodied carbon studies. It’s not a full life cycle assessment but it gives enough information to make decisions.”

The fact that all stakeholders could access the tool ensured that everyone was on the same page on the effort to reduce the project’s embodied carbon.

“Having a tool that was accessible and easy to use by anybody is one of the key things that helped to visually communicate to the whole design team and client teams with varied levels of embodied carbon understanding what the possibilities might be,” de Hoog says. “We knew that it might not be realistic to get to net zero for this project without carbon offsets, but with the tool we could home in on materials and design efficiency studies to show what’s probable.”

Developing the tool

The IStructE tool was developed after the institution published a guide called How to Calculate Embodied Carbon in 2020. While feedback was positive, there was immediate demand for a digital tool that did the calculations automatically.

The institution was approached by several of its members offering their own carbon calculation tools for adaptation. IStructE head of climate action Will Arnold looked through them and found that the one closest to what he envisioned was created by civil and structural engineering consultant ElliottWood.

The tool enabled us to have a conversation with the architect and client team using real data

ElliottWood and the IStructE collaborated to adapt the tool over several months using IStructE parameters and Arnold’s vision of how to make it accessible.

“I wanted it to be simple enough that a complete novice could pick it up and use it to very quickly work out the embodied carbon footprint of a project,” he says. “Then I wanted it to be customisable so a more advanced user could take it to bits and do other things with it, such as [adding] different carbon factors.”

Once complete, the Structural Carbon Tool was made freely available to download from the IStructE website.

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