A Comparative Analysis of Multi-Criteria Decision-Making Methods and Normalization Techniques in Holistic Sustainability Assessment for Engineering Applications

The sustainability evaluation of engineering processes and structures is a multifaceted challenge, requiring the integration of diverse and often conflicting criteria. A comprehensive Sustainability Index (SI) has been developed to address this complexity, utilizing Multi-Criteria Decision-Making (MCDM), to provide balanced and effective solutions. The SI incorporates key metrics across performance, environmental impact, economic factors, social dimensions, and circular economy principles. Selecting the most appropriate MCDM tool for problems involving multiple criteria is a pivotal challenge in holistic sustainability assessments. Among the numerous methods documented in the literature, the Weighted Sum Method, Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), modified TOPSIS, COPRAS and VIKOR are frequently employed for ranking alternatives. The calculation of SI is based on the normalized data, with the selection of both the MCDM tool and the normalization method playing a crucial role in determining the robustness and reliability of the results. This study investigates the impact of various MCDM tools on the decision-making process and examines how prominent normalization methods, including min-max normalization, vector normalization, z-score normalization, robust normalization and sum normalization, affect the final outcomes. Using a dataset from the aviation sector, a typical aircraft component serves as a case study for a holistic sustainability assessment. A detailed sensitivity analysis investigates the influence of MCDM tools, normalization methods, and weight variations on the holistic SI. This study highlights the importance of selecting appropriate MCDM tools and normalization methods to enhance the interpretability, robustness, reliability, and consistency of sustainability assessments in engineering applications.