Brogan MacDonald is Head of Sustainability in Building Structures at Ramboll UK, a Chartered Civil Engineer and Chartered Environmentalist. Where others see aging urban stock, she sees an inventory of value — treating existing buildings as material banks — an approach she calls inventory-constrained design. This month, she was named the Royal Academy of Engineering's overall Young Engineer of the Year. With London Climate Action Week on the agenda, we share our interview with her, focused on the English capital and its value for reuse and urban mining.

You live and work in a city that never stops building. If someone asks you what sustainable construction looks like in London, where do you begin?

London is dense and deeply layered, so the most sustainable thing we can do is keep using the buildings and assets we already have. Seeing the standing city as a resource is where sustainable construction in London genuinely starts.

Public consciousness has caught up with the environmental damage caused by aviation and fast fashion. Why has the built environment stayed below the radar?

That is the fascinating gap. People understand the environmental costs of a flight and of fast fashion; the built environment deserves the same shared awareness. Making that story accessible is something I care about deeply, because once it lands, the logic of reuse becomes irresistible. A structure that has outgrown its use as a commercial office can make a wonderful hotel, student housing, or shopping center. The building stays; the use evolves. That is a hopeful message, and it deserves a wider audience.

For everyone working in city-making, where does the real opportunity lie?

The opportunity is in the materials and building types we already have. The shift is to see existing buildings as material banks — as urban mines — and to design from an inventory: a fixed kit of parts, almost like being handed a catalog and asked to build something wonderful from exactly what it contains.

Writing after London Climate Action Week, the Holcim Foundation's Executive Director reflects on emerging ideas for planning and funding better urban development that includes the reuse of existing resources.

Housing came up in conversation after conversation across London Climate Action Weeek. At the Barbican — itself a 1970s modernist model of dense, mixed-use living that has aged into one of London's most coherent neighborhoods — the Holcim Foundation supported C40 Cities to host a panel on housing and urban regeneration.

The session drew the full value chain into one room. Two points from the conversation stayed with me. Delivery at scale needs city halls to bring in people who speak the language of investment — public servants fluent enough to structure deals and draw private capital toward public goals. And regeneration makes sound financial sense: reusing land a city has already serviced puts its existing roads, schools, and hospitals back to work, sparing the new infrastructure that greenfield housing always demands.

CityMakers Live launched in Bucharest this month with “Deeper than Density,” an evening on how a fast-growing city can evolve sustainably. The panel event was held at Grivița 53, a community-built theater recognized by the Holcim Foundation Awards in 2017. From a an inspiring conversation between architects, economists, developers, and engineers, we’ve pulled out three compelling quotes related to building better cities.