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.

In 2016, Empa inaugurated NEST ("Next Evolution in Sustainable Building Technologies"), a new type of building that expedites the innovation process by providing a platform where new developments in the built environment can be tested, verified and demonstrated under realistic conditions. One of the units within is the "Urban Mining and Recycling" (UMAR) unit by Werner Sobek with Dirk E. Hebel and Felix Heisel-a unit that demonstrates how a responsible approach of dealing with natural resources can go hand in hand with an appealing architectural design. The unit is underpinned by the proposition that all the resources required to construct the building must be fully reusable, recyclable or compostable and are therefore part of a circular economy; propositions that can be tested here in a kind of "real-life" laboratory. Empa's Technology & Society Laboratory (TSL) established-in parallel to the integration of this unit into the NEST building-an ecological evaluation of this unit, using the tool of "life cycle assessment" (LCA). Compared to a hypothetical reference unit in same size and standard constructed out of common building materials such as concrete, the UMAR unit shows over its entire life cycle a reduction of the environmental impacts of 18% (for grey energy) to more than 40% (global warming potential).