Modern cities emerged as the main accumulator for primary and waste materials. Recovery of both types from buildings after demolition/disassembly creates a secondary material stream that could relieve pressure from primary resources. Urban mining represents this circular approach, and its application depends on redefining current construction practice. Through the life cycle assessment (LCA) methodology and assuming primary resources as step zero of urban mining, this study estimates the impacts and benefits of conventional versus a circular construction practice applied to various buildings with different parameters and the country-level environmental potential savings that could be achieved through this switch in construction practice—using the increase of the residential building stock in Switzerland between 2012 and 2016 as a case study and key values from the experimental unit “Urban Mining and Recycling”, designed by Werner Sobek with Dirk E. Hebel and Felix Heisel and installed inside the NEST (Next Evolution in Sustainable Building Technologies) research building on the Empa campus in Switzerland. The results exhibit lower total impacts (at least 16% in each examined impact category) at building level and resulting benefits (i.e., 68–117 kt CO₂-Eq) at country level over five years, which can be further reduced/increased respectively by using existing or recycled components, instead of virgin materials.

The article at hand follows the understanding that future cities cannot be built the same way as existing ones, inducing a radical paradigm shift in how we produce and use materials for the construction of our habitat in the 21st century. In search of a methodology for an integrated, holistic, and interdisciplinary development of such new materials and construction technologies, the chair of Sustainable Construction at KIT Karlsruhe proposes the concept of “prototypological” research. Coined through joining the terms “prototype” and “typology”, prototypology represents a full-scale application, that is an experiment and proof in itself to effectively and holistically discover all connected aspects and address unknowns of a specific question, yet at the same time is part of a bigger and systematic test series of such different typologies with similar characteristics, yet varying parameters. The second part of the article applies this method to the research on mycelium-bound building materials, and specifically to the four prototypologies MycoTree, UMAR, Rumah Tambah, and Futurium. The conclusion aims to place the results into the bigger research context, calling for a new type of architectural research.

Circular construction is a design task that requires new datasets and computational tools for matching supply and demand within an urban circular system. Material passports (MPs) contain detailed inventories of materials and products, as well as their specifications, location, and connection details. Circularity indicators (CIs) allow an assessment of a design’s environmental impacts with respect to circularity: the degree to which solutions minimise extraction and waste in favour of reusable, renewable, or recyclable resources both in construction and at end-of-use. Often implemented as an extension to detailed BIM models, MPs and CIs are presently applied in the permit and documentation phases. However, these metrics also establish parameters in early design phases, where circular design thinking and evaluation are most impactful. Circular construction consequently calls for a new suite of design tools that can be integrated into existing workflows, are applicable within the uncertain context of the early design phase, and ideally offer immediate feedback related to formal deliberations, structural considerations, material selection, and detailing. This chapter describes the importance of CIs as design parameters across phases with a special focus on recent early design developments such as the software application RhinoCircular.