Although Industrial Ecology (IE) aims to optimise resource use, reduce environmental impacts, and promote sustainable systems, many of its methods and proposed solutions rely on normative decisions that often remain implicit. This thesis explores the foundational role of ethics in IE by examining how explicit and implicit moral assumptions influence its research and applications. Drawing on examples such as the Circular Economy, green growth and degrowth, Life Cycle Assessment, and anthropogenic impacts on nonhuman animals, this research shows how unresolved ethical tensions can shape both the direction and effectiveness of IE and sustainability research more broadly. In response, this study develops a systematic tool to help researchers identify, evaluate, and communicate the moral assumptions underpinning their work.
To explore how ethics is explicitly applied, a targeted literature review of 32 IE-related papers was conducted. Each paper was assessed for its use of ethical theories, its moral assumptions, and the role these play in guiding research outcomes. While a wide variety of ethical theories are referenced in the literature, no single one dominates the field. Nonetheless, outcome-based reasoning, focused on how people or animals would be affected, is consistently used to justify normative choices. The analysed papers also pay special attention to the perspectives of underrepresented groups, such as informal workers, nonhuman animals, and future generations.
To analyse implicit ethical views, two case studies covering 53 papers were conducted: one on green growth versus degrowth, and one on anthropogenic impacts on nonhuman animals. The results suggest that moral disagreements are often rooted in differences in reasoning and available information, rather than in fundamentally opposing and irreconcilable views. Across both case studies, normative arguments again tended to rely on the anticipated impacts on affected groups, reinforcing earlier findings. These results were presented in a Delphi study with a panel of academic experts, who discussed them from multiple perspectives. Despite some differences in interpretation, participants broadly supported the need for moral pluralism, transparency, and experience-based ethical reasoning, while cautioning against rigid, prescriptive frameworks.
Building on these insights, this thesis proposes a non-prescriptive framework for evaluating moral assumptions in sustainability research: the Descriptive Holistic Moral Framework (DHMF). Grounded in four key premises that emerged from this research, the DHMF centres on the lived experiences of all sentient beings affected by sustainability-related decisions. It forms the foundation for the Holistic Moral Evaluation (HoME) Profile, which is a one-page overview designed to help researchers summarise their scientific contribution, core recommendation, moral assumptions, and anticipated experiential impacts. By making ethical reasoning more visible and accessible, the HoME Profile supports clearer communication, critical reflection, and broader engagement with stakeholders, even those without a scientific background.
Ultimately, this thesis argues that ethical reflection must become a core part of sustainability research. The DHMF and HoME Profile do not replace existing ethical theories but complement them by promoting transparency, inclusivity, and shared responsibility in addressing the urgent and complex sustainability challenges of the 21st century.

The number of pollinator species in the Netherlands is declining, critically pressuring systems depending on their pollination function in the ecosystem. This includes ensuring the pollination of most of the grown crops for food supply to human populations. Additionally, society faces the threat of bee diversity loss in the Netherlands, and worldwide. This research entails the spatial quantification of pollen and nectar in the Netherlands over the months in 2022. It encompasses different methods of quantification, from measuring an attractiveness proxy based on predicted presence (SDMs) to attributing production values based on the plant communities present in different land uses and the classification of urban areas into different land uses. It yields into monthly distributions and a yearly average nectar production map which was compared to bee diversity distribution. This allowed to identify areas imbalanced in food supply and demand that require extra attention. These results can then be handed to decision makers for development of better management practices regarding social, technical, or governmental implementations. It could ensure an increase in the amounts of pollen and nectar and further help the conservation of critical species. The findings are that the natural areas are the only ones with a matching high bee diversity and high nectar production. The production in itself is evenly distributed geographically. Over the months, the production of both pollen and nectar reaches a peak in spring while nectar production has a second peak in autumn. On average, the methods yield into different peaks of production for nectar, either May or September. This study lays as a foundation for future research through the identification of missing information in literature. It creates a methodological pathway and highlights what could be obtained from a similar research with more data available.

Reducing meat consumption is considered a crucial and urgent element in terms of reaching climate targets, public health and the protection of animal welfare. Especially in industrialised countries, it is considered the most important recommendation in the field of sustainable food consumption. The transition is difficult to realise, as meat consumption is a complex area involving numerous institutions and stakeholders with conflicting interests and consumers with very different opinions and behaviour. Meat consumption is the result of diverse individual factors, while being rooted in culture and social norms. It is thus considered challenging for policymakers to set this transition in motion, as intervening in the system comes with uncertainties, a lack of understanding, and possibly resistance on both the stakeholder and consumer side. Simulation models can be supportive in such a case, as they can support an increased understanding of the system, while being able to deal with the transition and all its complexity. Specifically agent-based models can be a suitable tool to support policymakers in making sense of this transition, as this type of modelling can deal with heterogeneity of consumers and is able to provide insight on how various policy interventions affect the individual and overall system behaviour.

The process of developing a simulation model for policy support using a technique that is not widely understood and accepted yet, can be challenging. Participatory modelling is a method in which stakeholders are involved throughout the modelling process to promote social learning and achieve model improvement. In this thesis, a participatory modelling process was designed to identify the potential use of agent-based modelling in reducing meat consumption in the Netherlands. The study focused on including elements of behaviour in the ex-ante evaluation of policy with the use of an agent-based model.

An agent-based model representing meat consumption behaviour of Dutch young adults was evaluated and improved together with a group of participants. Knowledge elicitation with the stakeholders working in the field of policymaking, research, and academia occurred through interviews, workshops, and mind mapping. The key findings of these sessions were that the participants desire to gain understanding on the socio-cultural factors influencing meat consumption and how these can be targeted with interventions. To respond to this lack of knowledge, the agent-based model was adjusted to capture meat consumption behaviour according to the COM-B wheel. This is a theoretical framework in which behaviour is categorised into physical and psychological capability, reflective and automatic motivation, and physical and social opportunity. In the agent-based model, consumers select and consume meals from a supermarket, take-away, or restaurant. Dietary preferences are based on knowledge and skills, environmental and animal welfare concerns, income, desired meat consumption, and social norms. The consumers are able to adapt their dietary preferences through reflection processes. The individual profiles were empirically grounded with input data from a cross-sectional questionnaire.

The agent-based model was used to study the effectiveness of various policy pathways that were formulated in consultation with involved participants. The policy pathways included in this study were various meat price increases, an increase of the vegetarian representation in the food environment, a social marketing campaign targeted at social norms, and combinations of the three. Of these interventions, meat price increases showed to be most effective in reducing the overall meat consumption. Increasing the vegetarian representation in the choice was effective, but to a lesser extent. The social marketing campaign on social norms showed no direct effect on the amount of meat consumed. When interventions were combined, even higher reductions were observed.

This study sheds a light on how the field of policy and science can together work on a gained understanding of this complex transition, with the use of agent-based modelling.