The issue of sustainability has received substantial attention internationally. It is spreading widely through policy, industry, commerce, research, academia, and other arenas. However, most previous studies on product sustainability were conducted based on a consideration of environmental protection, economic prosperity, and social wellbeing criteria, but there was less representation of specific social wellbeing criteria. The main objective of this study was to formulate well-defined ergonomics-based criteria for product sustainability evaluation and to validate the importance of the identified factors using a fuzzy Delphi method. In this paper, ergonomics-based product sustainability factors are organized by sustainability categories and grouped into employee wellbeing, the economy, and the environment. In the context of manufacturing, evaluating product sustainability from an ergonomics perspective provides more comprehensive social dimension criteria by addressing human characteristics, behavior, performance, human interaction with a product, workplace, working environment, and the product across its life cycle. In addition, a Delphi questionnaire, designed with a nine-point scale, was applied to obtain expert opinions on the importance of each factor; the opinions were combined for each factor by considering the degree of importance assigned to the experts, and the similarities and differences between expert opinions. Finally, high-priority factors were screened from the sustainability categories based on their respective threshold value. Knowing these high-priority factors will help manufacturing industries allocate their resources accordingly for sustainability improvement.

Production process sustainability refers to a manufacturing system in which manufacturing industries produce products in a sustainable way. In recent years, sustainability has become a major concern and challenge for manufacturing systems because of growing consciousness of the effects of their activities on the environment, society, and economy. Different organizational reports and the academic literature have proposed indicators of sustainable manufacturing that help to measure product and process sustainability. However, little of the previous research is related to employee-activity based indicators for production process sustainability. To bridge the gap, this study identified a set of indicators of production process sustainability based on direct and indirect impacts of manufacturing activities on employees, who are key resources in the entire production process, for efficiently applying a sustainability perspective. In addition, the paper provides an evaluation model for selecting relatively important indicators based on expert opinions. A fuzzy Delphi method was applied for the screening process of the decision makers (experts). A Delphi questionnaire prepared with a nine-point linguistic scale corresponding to respective linguistic variables was utilized to assess expert opinions on the importance of each indicator. These expert opinions were aggregated for each indicator by using an adopted algorithm that considers the degree of importance allocated to the decision makers, and the similarity and distance among decision maker opinions. Lastly, the key employee-activity based indicators were chosen based on the threshold value set.