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Die Kreislaufwirtschaft zielt unter anderem darauf ab, Abfall als Rohstoff für neue Produkte zu nutzen. Bei Ökobilanzen von Produkten stellt sich diesbezüglich die Frage, wie sich im offenen Kreislauf rezyklierter oder thermisch verwerteter Abfall bewerten lässt. Für die Bewertung von Produktsystemen sind zwei Allokationsmethoden üblich: Die Cut-Off Methode, welche den Einsatz von Recyclingmaterialien begünstigt und die Avoided Burden Methode, welche die Abgabe von recyclingfähigem Material begünstigt. Wir diskutieren diese beiden Methoden hinsichtlich ihrer Eignung zur Bewertung einer Kreislaufwirtschaft, gemessen an der europäischen Abfallhierarchie. Als Fallbeispiel dienen verschiedene End-of-Life-Szenarien für Glas und den Kunststoff Polypropylen, die wir mit Hilfe der Umweltindikatoren Material Footprint und Carbon Footprint bewertet haben. Als Ergebnis zeigt sich, dass die Anwendung von Avoided Burden im Fall einer thermischen Verwertung in einer Müllverbrennungsanlage problematisch ist. Zum einen ergibt sich in diesem Fall ein negativer Material Footprint, falls dadurch ein Steinkohlekraftwerk substituiert wird, zum anderen wird die Abfallhierarchie teilweise übergangen, da die thermische Verwertung günstiger erscheint als Recycling. Des Weiteren wurde herausgestellt, dass die oberste Priorität in der Abfallhierarchie, die Vermeidung, durch den Cut-Off Ansatz höher begünstigt wird, als durch die Avoided Burden Methode.
Die Umweltauswirkungen von Teil-, Miet- oder Tauschangeboten aus dem Bereich der Sharing Economy werden zumeist aus einer Nachhaltigkeitsperspektive betrachtet und dementsprechend mit einer Verminderung des Ressourcenverbrauchs sowie einer gesteigerten Ressourceneffizienz verbunden. Handelt es sich bei Sharing Economy tatsächlich um eine ressourcenschonende, energieeffiziente und für den "Massenmarkt" geeignete Konsumalternative oder haben wir es vielmehr mit einer kurzzeitigen Nischeninnovation einzelner Lifestyle-Communities zu tun?
In the face of growing popularity of eco-feedback innovations, recent studies draw attention to the relevance of the human factor for a more effective design of eco-feedback. This paper explores these challenges more deeply by employing a mixed methods approach. We provide in-situ insights from a Living Lab experiment on the effect of smart home systems and traffic light feedback on heating energy consumption in private households. Our results from an interrupted time series analysis of logged data on indoor room temperature, CO2 concentration and consumption of natural gas show that the interventions do not affect heating as expected, neither for automating behaviour via high-tech smart home systems nor via low-tech traffic light feedback. Smart home systems do not promise a significant reduction of heating energy consumption and a traffic light feedback on indoor air quality does not lead to a reaction of indoor CO2 concentrations, but may reduce heating energy consumption. Qualitative interviews on heating practices of participants suggests that comfort temperatures, lack of competences and inert heating systems do override expected effects of the feedback interventions. We propose that high-tech smart home systems should carefully consider the handling competences of users. Low-tech feedback products on the other hand should by design stronger address user experience factors like comfort temperatures.
Transformative Forschung hat einen klaren normativen Transformationsanspruch, jedoch ist dieser oftmals weder einfach umzusetzen noch zu evaluieren. Denn auch in der Forschung muss die Komplexität der Transformation berücksichtigt werden. In der Nachwuchsgruppe UrbanUp wurden im Reallabor Wuppertal gemeinsam mit der Praxis Interventionen durchgeführt, die hier exemplarisch beschrieben werden und in denen Wissen über die Verstetigung von Nachhaltigkeitsnischen generiert werden sollte. Dabei wurden verschiedene Frei- und Lernräume geschaffen, die den Transformationsanspruch der Nachwuchsgruppe bilden.
To date, the circular economy has fallen short of its promise to reduce our resource demand and transform our production and consumption system. One key problem is the lack of understanding that highly promising strategies such as refuse, rethink, and reduce can be properly addressed using research on sufficiency. This article argues that a shift in focus is required in research and policy development from consumers who buy and handle circularly designed products to consumption patterns that follow the logic of sufficiency and explain how sufficiency-oriented concepts can be incorporated into existing social practices. The authors show that sufficiency is not necessarily as radical and unattractive as is often claimed, making it a suitable yet underrated strategy for sustainability and the transition to an effective circular economy. The case of urban gardening shows that small interventions can have far-reaching effects and transform consumption patterns as the logic of availability is contested by newly developed concepts of "enoughness" and opposition to "über-availability." The authors propose utilizing comprehensive state-of-the-art theories of consumption and human action when developing strategies and policies to make the circular economy sustainable while being more critical of utilitarian approaches. Using social practice theories that have proven to be beneficial allows human actions to be comprehensively analyzed by recognizing their embeddedness in social and material frameworks; addressing the meaning, competences, and materials of routinized human behavior; and examining indirect effects.
Quantitative environmental assessments are crucial in working effectively towards sustainable production and consumption patterns. Over the last decades, life cycle assessments (LCA) have been established as a viable means of measuring the environmental impacts of products along the supply chain. In regard to user and consumption patterns, however, methodological weaknesses have been reported and, several attempts have been made to improve LCA accordingly, for example, by including higher order effects and behavioural science support. In a discussion of such approaches, we show that there has been no explicit attention to the concepts of consumption, often leading to product-centred assessments. We introduce social practice theories in order to make consumption patterns accessible to LCA. Social practices are routinised actions comprising interconnected elements (materials, competences, and meanings), which make them conceivable as one entity (e.g. cooking). Because most social practices include some sort of consumption (materials, energy, air), we were able to develop a framework which links social practices to the life cycle inventory of LCA. The proposed framework provides a new perspective of quantitative environmental assessments by switching the focus from products or users to social practices. Accordingly, we see the opportunity in overcoming the reductionist view that people are just users of products, and instead we see them as practitioners in social practises. This change could enable new methods of interdisciplinary research on consumption, integrating intend-oriented social sciences and impact-oriented assessments. However, the framework requires further revision and, especially, empirical validation.
At the heart of transition research lies the question of how to "scale up" sustainable alternatives from a protected niche to the creation of mainstream practices. While upscaling processes are often seen as an essential element that contributes to societal transformation, upscaling itself remains a fuzzy concept. We argue that some fundamental dilemmas of upscaling can be identified, for example, the different understanding of the concept by researchers and practitioners. The dilemmas should be addressed in a more reflexive way by those from the worlds of science and practice who are involved in collaborative research settings.
Nowadays, the main impetus to apply additive manufacturing (AM) of metals is the high geometric flexibility of the processes and its ability to produce pilot or small batch series. In contrast, resource and energy intensities are often not considered as constraints, even though the turnout of additive manufacturing is high, at least compared to chip removing processes.
The study at hand analyses the material characteristics and environmental impacts of a hose nozzle as an example of a commercial product of simple geometry. The production routes turning (conventional manufacturing) and laser beam melting (additive manufacturing) are compared to each other in terms of natural resource use, climate change potential and primary energy demand. It is found, that the product shows a lower demand for natural resources when produced via AM, but higher carbon emissions and energy demand when using a steel, that is mainly (80%) produced from high-alloyed steel scrap. However, different case studies during the sensitivity analyses showed that a number of factors highly influence the results: the steel source as well as the source of electricity play a major role in determining the environmental performance of the production routes. The authors also found that other production processes (here cold forging of tubes) might be an eco-friendly alternative to both routes, if feasible from an economic point of view.
In regard to the material characteristics, experimental testing revealed that the material advantages of AM produced hose nozzles (in particular higher yield strength) are reduced after a solution heat treatment is applied to the as-produced material, in order to increase corrosion resistance. However, products that do not require this production step might benefit from the higher yield strength, as a lower wall thickness could be realised.