Urban mining: buildings as material storage

February 24, 2025

Real estate as warehouses, cities as quarries. The example of the Patrick Henry Village in Heidelberg shows that when different players cooperate wisely, it pays off in the long term — on several levels.

Construction waste accounts for around half of all waste worldwide... Landfill capacities are reaching their limits... The construction and real estate sector causes 40 percent of the greenhouse gases released globally... Raw materials such as sand, gravel and ores are not available indefinitely... The problems are well known, the call for change is loud. The message is: Anyone who wants to be sustainable as part of the construction sector must become recyclable — because it is ecologically correct and economically necessary.

The change has already begun. Using urban mining as a strategy to use resources more productively. Here, real estate is raw material warehouses and cities are quarries of the future. The principle behind this is ancient. People from earlier centuries used stones from old castles to build new settlements; for the Rubble Women, the buildings destroyed in the Second World War were urban mines. Urban mining today is approaching the Cradle to Cradle ideal of a world without waste. A world in which our entire life is organized in such a way that materials circulate in biological or technical cycles — inspired by nature, in which the old is the nutrient for the new.

In the case of real estate, this means, for example: Once built in, concrete can be reused again and again — without loss of quality or value. The raw materials used are not lost. They are stored; the buildings are their storage. Prerequisite: the recyclable materials are chemically harmless, easy to dismantle and can be separated by type. The RAG building in Essen, the town hall in Venlo, the Dutch town hall and the wooden hybrid building “The Cradle” in Düsseldorf show how new properties can be created using the Cradle to Cradle design principle. They all have a material passport with all information about their recyclability. Experts from EPEA GmbH — Part of Drees & Sommer, an international innovation partner for environmentally friendly industrial products and buildings, have developed this Circularity Passport — Buildings in cooperation with BIM colleagues. It serves as a documentation tool and as an optimization tool in planning.

There is almost always a lack of data on the material composition of buildings. But that is not an insurmountable obstacle. Information can be obtained through research, analyses — or estimates. EPEA's Urban Mining Screener calculates them without complex inspections purely on the basis of the construction site, year of construction, building volume and building type at the push of a button — and delivers pleasantly realistic results, as detailed studies show.

One project that used the Urban Mining Screener is Patrick Henry Village in Heidelberg, a 110-hectare former residential development for members of the US Army, which creates apartments for 10,000 people and space for around 5,000 jobs. The Patrick Henry Village is part of the “Circular City Heidelberg” pilot project, in which the municipality creates a digital material register in the sense of urban mining. On board are — in addition to EPEA responsible for the design — Heidelberg Materials, one of the largest building materials companies in the world, and the Madaster platform, which, among other things, stores material values and determines residual raw material values. According to Urban Mining Screener, the 325 buildings that must be renovated or demolished for the new settlement are a gigantic raw materials warehouse with around 465,884 tons of material. Around half of it is concrete, a fifth of bricks and a good five percent of it is metal.

The truth is that it is currently often still cheaper to build a new one than to apply the re-use principle. It is not smarter per se, certainly not in the long term. The future belongs to urban mining, especially as it will soon be enshrined in regulatory terms. Buildings based on the Cradle to Cradle design principle are positive for the climate and people, conserve resources and retain their value in the long term. This must be even more popular in the construction and real estate sector.

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