On the one hand, there is a demolition ready for demolition in the 1950s, which is difficult to repurpose, and on the other hand, there is Heidelberg's ambitious strategy: to become a Circular City. On the huge site of the old barracks, it makes sense to show what is currently possible in terms of circular economy: to draw materials from existing buildings that do not end up in waste, but are reused locally or circulated in a high-quality manner. The principle is called urban mining. Urban exploration. Use existing houses and roads as raw materials storage. It is currently one of the most important concepts in the construction industry for transitioning into a resource transition in the long term

More than 300 buildings are to be demolished, renovated or converted and reused in the best possible way in Patrick Henry Village, a district with future apartments for 10,000 people and space for 5,000 jobs. But what exactly can you actually use for a new building? A question that the so-called digital building material register can answer. The cadastre provides information on which materials, in which quantity and quality, are to be expected in the event of a building demolition or a comprehensive renovation. The two pillars: Urban Mining Screener from EPEA and Madaster Building Database.

Urban Mining Screener is a program that can estimate their material composition at the push of a button based on building data such as construction location, year of construction, building volume or building type. EPEA analyses the existing components and building materials used and presents the data in a Building Circularity Passport, where they are assessed according to their recyclability. The collected data is then uploaded to the Madaster building database, so that a variety of helpful building data is then available for project development and regional material flow management.

Urban mining in existing buildings and circular construction is not only interesting from a climate perspective. In an economic sense, circular buildings are real gold mines for investors. For example, costs for future dismantling, conversion and landfilling are saved and the asset value increases by taking into account the residual material value, there is potential for value security and long-term value retention through circular building design and sustainable buildings, the image is improved and much more.

A lot has already happened in the former military town. The buildings were analysed according to age, size and construction method and provided data on the materials used. In this way, options can be shown even before dismantling as to whether and which treatment options and recycling routes exist for the individual material flows and what can be needed for new projects, what makes sense for the project, which saves costs, raw materials and CO2.

For Heidelberg, the project represents a further expansion of its pioneering role in the areas of circular construction, reuse of materials from existing buildings, and management of building materials and secondary raw materials. Patrick Henry Village (PHP) could become a lighthouse project within the city's Circular City Strategy, lay the foundation for sustainable building material recycling and construction, and be a blueprint for many other projects in other cities.

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Photo: Patrick Henry Village pilot project, Heidelberg © Matthias Heinrich, EPEA

Author: Matthias Heinrich