One of the more persistent misconceptions surrounding embodied carbon is that calculations should wait until material quantities are fully defined.
In reality, the opposite is often true.
During concept design, engineers have the greatest influence over a building's carbon footprint because they are still evaluating structural systems, spans and material strategies. Once those decisions have been finalised, opportunities for significant reductions diminish rapidly, while the cost of redesign increases. The presentation illustrates this relationship clearly, showing that the ability to influence carbon falls as a project progresses, even as estimating accuracy improves.
That does not mean early-stage calculations need to be perfect. They simply need to be robust enough to compare options and steer design in the right direction. Preliminary quantities, benchmark data and engineering judgement are often sufficient to identify whether one structural approach is likely to deliver a lower carbon outcome than another.
