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How do we build sustainable best practice into our day-to-day work? Our RIBA-mapping exercise

Sustainability By David Rivers, Associate Director, London Structures – 23 October 2023

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David Rivers

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Seif Fahmy

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Ben Murphy

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The concept of zero carbon design is a bit of a perplexing one for structural engineers. Almost by definition, any active contribution we make on a project will add embodied carbon, be it the design of a multi-storey concrete frame from scratch or addition of new some new trimming steelwork to form a new whole in an existing floor plate.

Instead, for us, net zero primarily means minimising embodied carbon, at least at this stage in the journey. The less embodied carbon that is included in the project, the smaller the degree of offsets needed to cancel out.

This represents a bit of a departure from typical design practices in the traditional sense, where the main drivers would typically be cost, buildability and (often) minimising the number of columns to suit architectural aspirations and maximise usable space. The carbon agenda actually empowers us as engineers to push back on some of these historic limitations and drive for more efficient structural forms with less embodied carbon.

And there is a smorgasbord of really helpful information available to help us do this, such as the IStructE resource map and all of the linked documents, numerous guidance notes, calculation procedures and publications from the likes of the IStructE, RICS and LETI amongst others, practical efficiencies via contractor supply chains such as cement replacement, EAF steelwork and direct reuse of members and an ever growing list of exiting new products undergoing testing and gradually making their way to the market. Within Cundall, we have also developed tools of our own, allowing us to do things like undertake hundreds of scheme design permutations to determine the most efficient from an embodied carbon perspective in the same time it used to take to run through a handful manually, and use our Revit models to generate SCORS ratings and track their development through the life of a project.

Which is all fantastic. But also risks being quite daunting. The sheer quantity of information, and its application across various different stages of the design process, can make it a challenge to know where to start, and even with the best of intentions it is quite easy to feel a bit lost.

So we had a think about what we could do to help with this problem. Inspired by the work of the IStructE, who carried out a very useful exercise in mapping the typical stages of structural design to the RIBA stages that we all know and regularly use (the Structural Plan of Work), we decided to adopt a similar approach to sustainable interventions. Our logic was that if we could condense the available information down into more manageable chunks, and align them to the standard stages of design that everyone is already familiar with, they could be reviewed in a more manageable way, at the point of maximum possible impact, and over time become a standard part of the process; “business as usual”, rather than a well-intentioned afterthought.

First, we did our best to collate the information that is currently available and assign it to the different design stages. This was no easy task, complicated further by the fact that new information appears almost daily, but we managed to come up with something we considered sensible.

We then had a think about format. The beauty of the IStructE document is that it condenses a lot of information into a single page, and we wanted to achieve a similar “reference” page approach whilst also allowing for some more in-depth detail as well. We decided on a simplified headline page, mapping the RIBA stages and identifying the key interventions by sub-heading, providing a useful reference point that can be used as a summary in reports and project planning/reviews, but that also doubles as a contents page for the remainder of the document. This takes each sub-heading in turn and provides additional detail on things that can be done, with references out to available industry guidance where available.

The final step was to share this around for further comment and input, which is where we currently are, and we would welcome any thoughts or suggestions on how the document could be improved or expanded. The nature of such a document means it will always be out of date the second it is published given the rate of publication in this field, and we plan to continually update if over time, but initially we want to understand if the general format and aspiration of the document has been a success. There are so many easy wins we can take as an industry on the embodied carbon front simply by being aware and thinking about the right thing at the right time, and our hope is that this document will be a helpful step in embedding this thought process as best practice.

If you do have any thoughts, comments or ideas, please email them to and they will be gratefully received.