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Advancing Zero Carbon Design in structures through parametric scripting

Zero Carbon Design By Dominic Beer, Engineer – 25 May 2022

Screenshot of parametric script that calculates embodied carbon quantities for structural elements

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Dominic wearing white shirt standing in front of green wall

Dominic Beer

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With the world facing a climate emergency, the construction industry needs to rapidly decarbonise. Building structures have tended to be incredibly carbon intensive, particularly due to the choice of building materials. For example, emissions associated with concrete and steel production. As structural engineers, we hold a responsibility to minimise the carbon footprint of the structures we design. For the best chance of achieving this we should be considering and assessing embodied carbon at all stages in the design process, from the earliest concept to the finished building.

I have a passion for parametric design, a methodology that I think will be key to design net zero carbon structures. What is it? Parametric design is the practice of generating design data, for example a BIM model, using automated computer scripts, rather than creating it directly. To use an analogy, rather than cooking a meal ourselves, we give the computer the recipe and it cooks the meal pretty much instantaneously. My team and I use a visual programming tool called Grasshopper, along with traditional programming languages such as Python, to create scripts for generating our designs. Typically, we are generating structural/BIM models made up of beams, slabs, columns, and walls, utilising various 3rd party tools. There are numerous benefits to doing this. We can change the inputs of a script, for example a column spacing, and instantly produce a new output. This gives us the power to rapidly assess many iterations on a design very quickly. For standard/typical operations, we can reuse sections of script. We also have access and control over the data we produce, meaning we can organise and analyse it as required, helping us gain additional insights.

I am developing a suite of tools within Grasshopper to allow us to easily calculate embodied carbon data in these parametric scripts, with minimal additional work required. This is a thorough calculation, considering not only the carbon emitted when producing a material, but also the carbon associated with transporting it to site and the additional emissions attributed to wastage of material. The power of generating this data parametrically means that we could test many variations of a design, allowing us to quantify the environmental impact of certain design decisions. The tools are designed to be flexible and able to deal with data from various sources, whether it is a BIM model, some 3D geometry, or tables of data from Excel. Also, since the tools have been created in Grasshopper, they are able to be tweaked and adapted to more novel situations if projects require it.

There has been an encouraging deal of interest at Cundall, and we are now starting to integrate the tool into some current projects. I have also built the functionality for the toolset to be able to perform a carbon assessment of completed projects’ Revit models. Through analysing these we can identify how our previous designs performed and how they could have been improved, learning lessons we can then apply to future designs.

I am currently working hard to continue to develop these tools, and most importantly spreading their use across the business. Through combining a thorough assessment of a structure’s embodied carbon with the power, adaptability and control over data that come with a parametric workflow, we are in the best position for producing the sustainable solutions that are required to achieve a net zero carbon building.

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