Metrics-based dynamic product sustainability performance evaluation for advancing the circular economy

Creating products that support the circular economy (CE) requires evaluating product sustainability performance (PSP) and planning the production process during the design stage. Evaluating PSP disregarding demand and production variations over the time a product is produced can lead to significant calculation errors, and therefore, misinformed design decisions. This has severe consequences in the CE-focused closed-loop productions. However, current literature on product sustainability and circularity evaluation methods is largely design-specific and explicitly or implicitly assumes a steady-state production. Thus, there exists a gap in the literature concerning PSP forecasting over multi-period productions with closed-loop flows. Therefore, this paper proposes a metrics-based framework that quantifies, simulates, and forecasts the PSP, considering the dynamic variations in demand forecast, closed-loop resource constraints, and end-of-use resource allocations. Accordingly, based on the literature on PSP evaluation as well as production planning, and input from industry experts, a new methodology was formulated to synthesize and develop this framework. A numerical application demonstrates that the PSP significantly varies with the demand curve profile (up to 25% change in certain metrics), even when the product design is constant. Most importantly, this paper introduces the concept of PSP as a "dynamic" measure over the temporal dimension, providing a framework to evaluate it comprehensively and with greater accuracy. Thereupon, this concept transforms how sustainability and circularity are viewed conventionally. When adopted, the concept will offer the designers greater insights that significantly improve the product design and planning process to advance the CE.