A structured path to lower-carbon design: why sustainability is a process, not a product
This viewpoint is taken from the ‘Conversations in Momentum’ podcast, with Eidos’s Mark Boyle and Alex Edmonds. Listen to the full podcast here.
The built environment is responsible for around 40% of global carbon emissions, and roughly one-third of that comes from construction. As structural engineers, we play a significant role in shaping those numbers – and a significant role in reducing them. But achieving genuinely lower-carbon outcomes isn’t about chasing the latest material. It requires a disciplined, sequenced design process.
Too often, the industry jumps straight to specifying the “greenest” product available. But if we’ve already locked in an inefficient concept, changing the material is little more than a sticking plaster. For us at Eidos, sustainability starts at the beginning.
The first question is simple: what already exists on the site? Can we reuse a structure, retain a basement, or keep facades and foundations intact? On several recent projects, retaining basements avoided both demolition and temporary works – meaning lower embodied carbon before we even began detailed design.
Once we understand what can be reused, the next step is getting the concept right. That means considering materiality, structural form and constructability together, and doing it early. The further you progress through design, the harder it becomes to unwind decisions that require unnecessary temporary works or excess material.
Only after those stages do we move into element optimisation, where digital tools can help remove additional waste. Over the last decade, we’ve seen an explosion in optimisation technologies – but they must be used responsibly, with validation and engineering judgment, rather than as a shortcut.
It’s at this point – not the start – that material specification comes into play. Low-carbon steel, cement replacements and emerging products all have potential. But availability and cost pressures are real. If one project hoards the supply of green steel, the industry makes no net progress. We need a collective, not competitive, mindset.
New technologies are exciting, but we must adopt them sensibly. Early-stage products often struggle to reach viable scale; many disappear before wider uptake. As engineers, we can help bridge that gap by trialing materials in low-risk applications, proving performance and supporting growth rather than expecting instant perfection.
There are challenges – commercial, regulatory, cultural – but none are insurmountable. Meaningful carbon reduction is possible when we combine engineering rigour with honest conversations, bringing clients with us and making informed choices, not symbolic ones.
Sustainability isn’t a single decision. It’s the accumulation of better decisions, made in the right order.
