This thesis addresses the question of how to incorporate sustainability aspects into the make-or-buy decision process. In addition, there is a lack of support in the execution of these decisions in the operative work, as it is time-consuming and error-prone (Venkatesan, 1992; Welch & Nayak, 1992). For this reason, this thesis delimits the make-or-buy decision and focusses primarily on the operational outsourcing decision and its support. Consequently, this research not only explores the integration of sustainability in make-or-buy decisions, but also introduces the innovative approach of ontology-based meta-modelling for improved decision making and representation.

Firstly, the thesis analyses the make-or-buy decision-making process in order to identify the relevant aspects as representation requirements. Secondly, various modelling languages are considered and compared to assess whether they are suitable for the requirements identified. For this purpose, a design science research approach was applied, consisting of four qualitative interviews and a variety of literature.

As a result, an ontology-based meta-model has been designed and presented in AOAME, which consists of the identified main aspects to be considered in the decision, such as cost, supplier, item and sustainability. The deliverables were then evaluated by a focus group in order to verify the usability and comprehensibility of the model. Among other benefits, it could be proven that the model is designed to better capture the complexity of the decision-making process of outsourcing decisions, while considering environmental concerns. However, the outcomes of this research not only resolve the identified challenges and research gaps but also contribute insights into the strategic alignment of businesses with sustainability goals. By incorporating ontology-based meta-modelling, organizations can navigate the complex outsourcing decisions, ensuring a holistic representation that considers both traditional and ecological aspects. In addition, the results could raise awareness about the impact of make-or-buy decisions on sustainability, such as carbon emissions, and might encourage the choice of more sustainable production methods.