The circular economy applied to building is based on a simple idea: the material with the least footprint is the one that already exists and should not be manufactured again. Conserving and adapting existing structures, instead of demolishing and rebuilding, avoids a very important part of the embodied carbon, because it is precisely the structure and the foundation that are the elements with the greatest impact on a building.

Leading international projects have shown that reuse is technically viable and commercially competitive: renovations that have preserved most of the structure and the original core, even recovering entire facades, with savings of thousands of tons of CO₂. The technical key is to rigorously evaluate the capacity and condition of existing elements to certify their reuse with guarantees.

For engineering, this opens up a specific field of work: the audit and diagnosis of existing structures, the quantification of avoided carbon and the technical justification of reuse. For construction companies, it is a way of differentiating themselves in a market that is beginning to reward conservation over systematic demolition.