Can TRIZ (Theory of Inventive Problem Solving) strategies improve material substitution in eco-design?

The material substitution (MS) is a very effective eco-design strategy for reducing the environmental impacts in a product, albeit its application can be hindered because of the other product requirements, e.g. mechanical strengths, aesthetics, etc. However, approaches that explicitly support a strategic MS in problem-solving are missing in the literature. This paper compares the reduction of the environmental impacts in 153 case studies of comparative life cycle assessment (LCA), extracted from 113 scientific articles, associated with generic MS or strategic MS according to TRIZ (Russian acronym for “Theory of Inventive Problem Solving”) strategies. The association was manually performed by following a structured and step-divided procedure, where the case studies are reformulated and compared to the TRIZ strategies, by exploiting the analogy of some common ontological terms between TRIZ and design. The obtained results showed how TRIZ can be used to perform a more rational and strategic MS to meet both environmental sustainability and other product requirements, better than generic MS. The impact reduction is instead greater in all impact categories (+21% on average), whether the introduced materials are synthetic (+19% on average), natural (+13% on average), and recycled materials (+18% on average). Furthermore, the associations between the solutions that guarantee the greatest reductions in environmental impacts and the revised TRIZ strategies for MS have been determined in relation with application fields, types of products and materials. Compared to other contributions in the literature, the main novelties of this study are: the intersection between TRIZ and MS and its environmental evaluation, quantitative and enlarged to different standard categories and based on a wider and heterogeneous set of case studies. In conclusions, this study associated more quantitative environmental advantages to the provided set of revised TRIZ strategies for material substitution than generic material substitution on the basis of analogies with historical cases that inspired their formulation.