Greenhouse gas (GHG) emissions need to be reduced to limit global warming. Plastic production requires carbon raw materials and energy that are associated today with predominantly fossil raw materials and fossil GHG emissions. Worldwide, the plastic demand is increasing annually by 4%. Recycling technologies can help save or reduce GHG emissions, but they require comparative assessment. Thus, we assess mechanical recycling, chemical recycling by means of pyrolysis and a consecutive, complementary combination of both concerning Global Warming Potential (GWP) [CO2e], Cumulative Energy Demand (CED) [MJ/kg], carbon efficiency [%], and product costs [€] in a process‐oriented approach and within defined system boundaries. The developed techno‐economic and environmental assessment approach is demonstrated in a case study on recycling of separately collected mixed lightweight packaging (LWP) waste in Germany. In the recycling paths, the bulk materials polypropylene (PP), polyethylene (PE), polyvinylchloride (PVC), and polystyrene (PS) are assessed. The combined mechanical and chemical recycling (pyrolysis) of LWP waste shows considerable saving potentials in GWP (0.48 kg CO2e/kg input), CED (13.32 MJ/kg input), and cost (0.14 €/kg input) and a 16% higher carbon efficiency compared to the baseline scenario with state‐of‐the‐art mechanical recycling in Germany. This leads to a combined recycling potential between 2.5 and 2.8 million metric tons/year that could keep between 0.8 and 2 million metric tons/year additionally in the (circular) economy instead of incinerating them. This would be sufficient to reach both EU and German recycling rate targets (EC 2018). This article met the requirements for a gold‐silver JIE data openness badge described at http://jie.click/badges.

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Autoclaved aerated concrete (AAC) is used as masonry blocks and prefabricated reinforced elements preferably in residential buildings. Due to its porous structure and mineral composition, it combines low thermal conductivity and fire resistance properties. Consequently, the popularity of AAC increases. However, due to significant AAC production volumes in many European countries since the 1960s and 1970s and given building lifetimes, strongly increasing post-demolition AAC waste volumes can be expected in the following decades. Recycling these post-demolition AAC wastes could protect primary resources and landfill capacities and reduce greenhouse gas emissions. But, recycling of post-demolition AAC is not yet established. The majority of the waste is landfilled even though landfill capacities have decreased and the legal framework conditions in Europe regarding a circular economy are becoming stricter. Therefore, new recycling options are needed. Current research approaches propose different open-loop recycling routes for post-demolition AAC, e.g. lightweight aggregate concrete, lightweight mortar, no-fines concrete, floor screed, animal bedding, oil- and chemical binders, and insulating fills for voids and interstitial spaces. Additionally, closed-loop recycling is possible and under research. Finely ground post-demolition AAC powder can be directly used in AAC production or can be chemically converted to belite (C2S) clinker to substitute primary cement in AAC production. These promising recycling options are compared regarding environmental and economic aspects. We find that the resource consumption is lower in all recycling options since post-demolition AAC helps to save primary resources. Furthermore, greenhouse gas emissions associated with the substituted primary resources are saved - especially when substituting primary cement in closed-loop recycling. In economic terms, increasing landfill costs could be avoided, which leaves a considerable margin for the cost of pre-processing, transport and recycling. The results can help decision-makers to implement circular management for AAC by fostering post-demolition AAC recycling and reducing its landfilling.

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Porenbeton ist aufgrund seiner hervorragenden Dämmeigenschaften ein häufig verwendetes Baumaterial für Mauersteine sowie vorgefertigte bewehrte Bauteile und Mineraldämmplatten – mit wachsender Beliebtheit. Altporenbeton aus dem Abbruch und Rückbau von Gebäuden wird derzeit hauptsächlich deponiert. Deponiekapazitäten nehmen jedoch ab und der rechtliche Rahmen verlangt feste Recyclingquoten. Um ein hochwertiges Recyclingnetzwerk von Altporenbeton zu etablieren, werden Informationen über rezyklierbare Mengen, ihr zeitliches Aufkommen und ihre regionale Verteilung benötigt. Da diese bislang nicht vorhanden sind, wurde ein neues Modell zur Quantifizierung von Altporenbeton unter Nutzung historischer Porenbetonproduktion, Bautätigkeit, regionaler Marktanteile von Porenbeton und Gebäudelebensdauern entwickelt. Das Modell wurde für Deutschland im Zeitraum 1950–2050 (jahresgenau) mit geografischer Unterteilung in 401 Regionen angewendet. In den nächsten Jahrzehnten ist den Ergebnissen zufolge mit stark steigenden Altporenbetonaufkommen zu rechnen. Das Aufkommen in Deutschland könnte von 160.000 m3 (2000) über 1.200.000 m3 (2020) auf mehr als 4.000.000m3 (2050) ansteigen. Es werden signifikante Mengen v. a. in großen deutschen Städten wie Berlin, Hamburg, München, Bremen, Hannover, Köln, Frankfurt und Stuttgart erwartet. Diese Ergebnisse bieten eine Entscheidungshilfe für die Kreislaufführung von Altporenbeton in Bezug auf Standort‐ und Kapazitätsplanung sowie Logistik.