To this day, many techniques, tools and approaches have been developed and tested either on a lab scale or in pilot buildings around Europe. These demonstrations have served as great showcases for circular built environments, but they are yet to be demonstrated at higher level. Copenhagen, Hamburg, Helsinki region (City of Vantaa) and Greater London have teamed up with partners from the entire built environment value chain. The results will have a direct uptake in the value chain and enable cities to initiate circular transition. CIRCuIT will demonstrate three innovative solutions in the four cities: dismantle buildings to reuse materials; transformation and refurbishment; and design for disassembly and flexible construction. CIRCuIT will develop urban planning instruments to support cities in implementing circular construction solutions and initiate changes at system level; implement a Circularity Hub, a data platform to evaluate progress of circular economy and regenerative capacity; and set up a knowledge sharing structure, the CIRCuIT Academy, to promote upscaling of solutions. London, Hamburg, Helsinki region and Copenhagen have the ambition to bridge the implementation gap from individual pilots to the actual circular and regenerative city, by demonstrating the application of current and future developed tools and instruments for circular built environment at a city level in 36 demonstration projects. It is the intention to boost the regenerative capacity of the three cities and Helsinki region, and finalise the development of an advanced set of indicators for impact measurement in an effective and cross-European monitoring programme. The aim is to increase the regenerative capacity in the four cities, and to reduce the yearly consumption of virgin raw material by 20% in new built environments, and to show cost savings of 15%.

Mineral wool within construction and demolition waste (CDW) is considered largely unrecyclable. It is formed at a rate of 2.5 Mt/year and although it is only 0.2 % of total CDW, it requires disproportionally large space due to low density. The WOOL2LOOP project aims to close this material loop by introducing novel technology and value chain to CDW sorting, pretreatment, and processing. The quality of sorted mineral wool is upgraded by comparing and combining the following approaches: pre-demolition audit, robotized demolition and sorting, novel on-site analysis with time-gated Raman spectroscopy, and smart demolition practices. Pre-treatment involves logistical considerations and milling of the mineral wool waste to sufficiently small particles. Processing utilizes alkali-activation (i.e., geopolymerization) technology to convert reactive silica and alumina of the mineral wool into new building material products. Alkali-activation in this context is a completely new approach and it enables to diversely adjust the resulting material properties. Therefore, a broad selection of products were selected for WOOL2LOOP, ranging from relatively low to high value products: hollow core and pavement slabs, facade elements, acoustic panels, dry concrete, floor screed and 3D-printing equipment, for instance. All the required technologies and product manufacturing cases will be demonstrated in large-scale pilots with a wide geographic coverage within the EU. The consortium includes several leading large construction material enterprises and innovative SMEs to cover the whole value chain. Safety, health, environmental, and economic aspects are considered throughout the project. According to the preliminary calculations, there is a strong business potential in the WOOL2LOOP concept. Finally, the constantly increasing landfilling costs (approx. 250 M€ for mineral wool in the EU) create a clear economic driver for the project.