Product Eco-Design in the Era of the Circular Economy

1. Introduction

The design and development of products for daily use is rapidly changing due to the new constraints derived by the paradigms of sustainability and the circular economy (CE) [1,2]. The transition towards the CE is key to achieving global sustainability, as it promotes a restorative and regenerative system that minimizes waste, optimizes resource use, and enhances product lifecycles. Currently, the global economy consumes approximately 100 billion tons of materials annually, yet only 8.6% is cycled back into use [3]. This material inefficiency contributes to resource depletion, environmental degradation, and greenhouse gas emissions [4].

The issuing of new legislations/directive/action plans at national and international levels (e.g., the EU’s Circular Economy Action Plan and the EU’s Ecodesign Directive) and the increased consciousness of final users, especially in specific markets such as Northern Europe or Japan, are pushing companies to consider such themes in their product development processes [5,6]. The only effective way to face this new challenge consists of rethinking the way products are conceived [7]. Engineering design plays a central role in addressing these challenges by enabling the creation of products and systems that align with CE principles, such as recyclability, durability, and modularity [8]. As a consequence, designers and engineers are called to adopt eco-design methods and tools based on life cycle engineering approaches and to anticipate end-of-life issues in the early phase of design where the degrees of freedom to change the product features are higher and the impacts most effective [9]. Thus, environmental performance has become an additional important aspect of design to be considered together with other classical design drivers, such as quality, safety, functionality, and ergonomics [10,11]. This means that eco-design methodologies need to be effectively integrated in daily engineering practices, fostering the development and implementation of circular business models based on product life cycle extension and the accurate management of closed-loop end-of-life strategies (i.e., product reuse, product re-manufacturing, and material recycling) [12].

This Special Issue, ‘Product Eco-Design in the Era of the Circular Economy’, was proposed with the aim to collect relevant studies on novel eco-design methodologies strongly oriented to CE and life cycle engineering, as well as case studies that focus on the new paradigm of the CE or its measurement by means of circular indicators (i.e., disassembly, resource demand, life cycle assessment, and social engagement). In addition, this Special Issue is also open to review papers focused on particularly relevant designs for CE and end-of-life management themes.

After a rigorous peer review procedure, only the highest-quality papers have been selected for publication in this Special Issue. Among the ten published papers, three are literature reviews, while the other seven are research articles presenting new methods and/or discussing successful use cases. The total number of authors contributing to this Special Issue are thirty-four, and they are from the following seven EU countries: Denmark, France, Italy, Romania, Spain, Sweden, and the Netherlands.

2. Overview of the Published Articles

The work by Foschi et al. (2020) focused on the plastic packaging sector to demonstrate how the combined use of eco-design and life cycle assessment (LCA) methodologies has the potential to support the decision-making process to rethink the design of food packaging. On the basis of a careful analysis of the policies related to plastic prevention and packaging reduction, as well as eco-design applications in the context of packaging with special attention being paid to food packaging, the authors developed a case study in the frozen food industry in which packaging is crucial for several aspects: containment, protection, preservation, and promotion of the product. The use of eco-design strategies allowed the authors to redesign the standard packaging, eliminating the plastic cap and substituting it with a press-and-tear tab made of the same food-grade cardboard as the box, reaching a mono-material packaging design. In addition, the optimized shape of the innovative packaging allowed for an improved palletization during transport phases. The LCA comparison among the initial and optimized packaging solution showed a reduction in all the considered ILCD 2011+ impact categories, paving the way for a future environmental labeling, which is important also from a marketing perspective to communicate the efforts small–medium frozen food industries take towards sustainability.

The work by Martínez Leal et al. (2020) presented a circular eco-design approach, based on strict synergies between product designers and recycling-chains stakeholders, to favor the implementation of CE scenarios. The authors stated that both the design and end-of-life phases of the product life cycle must be connected to ensure the circularity of components and materials. This means that designers must design for and from an end-of-life perspective, while stakeholders in the product’s end-of-life simultaneously must work from and for the design. Firstly, a structured design for a recycling approach was developed to support designers in finding recycling hot-spots (i.e., the product characteristics that are the least efficient from a recycling perspective), as well as to define proposal-relevant guidelines to improve them. Then, a design for a recycling methodology was proposed to provide designers a way of selecting potential recycled materials to be used and evaluated through technical, economic, and environmental indicators for their convenience, feasibility, and appropriateness for new products. The Fairphone 2^® case study showed that the application of the proposed design of a recycling approach allowed the authors to understand that the most important criticalities are related to the numerosity and heterogeneity of the materials used in the product that strongly penalize material compatibility. With the subsequent application of the design of a recycling approach, the use of recycled polycarbonate (PC), derived from the recycling chain of electric and electronic equipment (WEEE) waste, was analyzed to discover that only from the environmental perspective was a clear benefit observable, while for both the technical and economic aspects, the virgin PC remained more convenient.

The work by van Dam et al. (2020) reviewed the state of the art to investigate how industrial design advancements have so far contributed to increasing knowledge in regard to the CE. A systematic literature review, conducted by following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol, selected 63 relevant papers, most of them published in the last 5 years. The major thematic areas investigated in the literature are as follows: design for circular production processes, design for circular consumption, design to support policy towards the CE, and design education for the CE. Among them the biggest thematic area is certainly the design for circular production processes, with papers mainly focused on distributed manufacturing, open design, and design for value recovery. In the field of circular consumption, the understanding of consumers’ routines and visual/communication design are the two principal aspects that can leverage the adoption of the CE. Papers related to policies, instead, are mainly focused on how design processes and methods can support the engagement of stakeholders for the purpose of policymaking, as well as on how policymakers can support the adoption of CE models. Regarding education, the reviewed papers mainly investigate how the current school/university curricula should be modified to include key CE approaches. The authors concluded that, even if a high number of papers exist, there is still the need to develop further research in the field of industrial design, and, in particular, eco-design, with a multidisciplinary and participatory approach to increase the impact of design research for the CE.

The work by Willskytt (2021) provided a literature review to investigate the extent to which existing design guidelines for resource-efficient products are applicable to consumables. Both general product design guidelines and product type-specific design guidelines are considered in the analysis. Scopus, Google Scholar, and Google were used databases to find the most relevant research works, which were then filtered by means of different criteria to reach the final sample of 32 papers, categorized in the two abovementioned groups using a life cycle criterion (production, use, transportation, and post-use). Analyzing the general product design guidelines, the author stated that they are more correlated to eco-design than to CE, since the papers belonging to the latter are more focused on more general strategies for circular products than on suggestions for designers. Such general guidelines are less significant in cases of dissipative consumables, while they can be considered relevant in cases of disposable products turned into reusable products. General product design guidelines can also be considered useful for educational purposes or as sources of inspiration. Product type-specific guidelines, on the one hand, limit innovation potentialities, since they confine the designer to a specific technology. On the other hand, they are essential in cases of products with very specific requirements (e.g., food products). In summary, general and product type-specific guidelines are complementary to each other, and further research is needed in the context of guidelines related to the use phase and concerning the transferability of product type-specific guidelines in other industrial sectors.

The work by Boix Rodríguez et al. (2021) aimed at defining a dedicated engineering design process to support the product development of new face masks, considering the specific context of the COVID-19 pandemic in Italy. The proposed methodology begins with an initial phase dedicated to environmental and circularity assessment using LCA and the Material Circularity Index (MCI) to analyze the most common existing products (i.e., surgical masks, FFP2 masks, reusable masks realized by 3D printing, and washable masks) and identify the strengths/weaknesses of each solution. These latter are then used to create a knowledge-based system for an eco-design of face masks, based on a set of eco-design guidelines aimed at minimizing their negative impacts on the environment. Finally, by following a systematic approach to design (requirements list, functional scheme, modularization, and technological implementation) integrated with the previously defined specific eco-design guidelines, a new mask design, with the same functionalities and performance of the existing one but with an improved environmental profile, was developed. The results confirm that a preventive approach is crucial to obtain environmental benefits also in emergency contexts, such as pandemics, when a very high demand of fossil-based products/materials is required.

The work by Torcătoru et al. (2022) had the purpose of investigating the current state of learning and management of the application of CE concepts for the development of industrial products, with special attention being paid to the COVID-19 pandemic period. A scientometric analysis in the Web of Science database, together with the application of the PRISMA filtering methodology, resulted in a body of knowledge consisting of 48 studies. Three main research directions were identified in the study: (i) management, which includes all of the concepts related to the organization of a company; (ii) packing, which includes all of the aspects related to the packaging of industrial products; and (iii) learning, which includes the aspects correlated to both learning and applying the methods and techniques for optimizing the CE. The authors concluded that the level of eco-design knowledge and expertise is currently scarce; thus, training on such themes should be strongly promoted among students already partaking in design studies at engineering faculties and also should become an ongoing process. However, without the implementation of effective management tools, the adoption of CE practices, such as the reduction in plastic packaging waste, does not seem possible on a large scale.

The work by Joustra et al. (2022) proposed a circular design method for products containing composite materials that generally have a long lifetime but are very hard to manage at the end-of-life stage. The proposed sequential design procedure is composed of six main steps: (i) definition of the intention to redesign composite products for circularity; (ii) exploration of a product’s life cycle considering the potential recovery loops together with the involved stakeholders; (iii) connection of recovery strategies with design aspects; (iv) selection of the most relevant design aspects to be considered in the implementation of each recovery strategy; (v) concept, embodiment, and detail design using the selected recovery strategies and design aspects; and (vi) proposal of the final solution for a circular composite product. The whole method was experimented in the context of five products belonging to the construction (one product), furniture (one product), and automotive (three products) sectors. Case studies allowed the authors to validate the proposed method in terms of effectiveness (i.e., if and how the method allows for the exploration of circular strategies), accessibility (i.e., the need for past knowledge to apply the method), and usability (i.e., the method’s applicability to design cases, as well as its use). As a conclusion, the authors highlighted the need to have a dedicated eco-design method available to exploit the potentiality of composite materials and products in the context of the CE.

The work by Boorsma et al. (2022) developed a comprehensive circularity indicator method specifically aimed at designers, aiming at overcoming the limitations of existing indicators in terms of depth and completeness, with consideration of semantic aspects. A six-step method development process based on the Design Science Research approach was used to finally define the Circular Product Readiness method. This latter method is based on an aggregated score calculated by using twenty indicators belonging to six main themes: (i) strategy and planning; (ii) hardware and software design; (iii) customer experience and care; (iv) product support service; (v) recirculation service; and (vi) recoverability. Two large companies experimented with the method to derive levels of readiness, strengths, and areas for improvement, product design semantics, life cycle focus, ease of application in industry, reliability, construct validity, content validity, comprehensibility, operationability, and transversality. The proposed method allowed them to assess in depth and integrate all aspects of the design to build a wider circular design approach which can help companies move towards circular ways of designing products and services.

The work by Tola et al. (2023) aimed to thoroughly review the state of the art on end-of-life management and demolition activities for ships and propose a conceptual framework for the effective recirculation of components and raw materials in this sector. Ship recycling originated during the first industrial revolution and for many years was mainly based on developed countries (such as the United States, the United Kingdom, and Germany), while currently the main ship recycling destinations are in South Asia. However, a systematic literature review presented by the authors, based on the in-depth analysis of seventy-eight relevant recent journal papers grouped in five clusters (economic, environmental, social, technological, and regulatory), highlighted the potential to implement a CE model and achieve a secondary raw materials market for the ship demolition sector in Europe, even if some barriers exist currently. Improving dialog and communication between all involved parties, adopting financial incentives and disincentives, training workers, using specific indicators to measure the sustainability and circularity of ships along the whole life cycle, and increasing the adoption of design for recycling and the cradle-to-cradle method are essential features to implement a CE-based framework in the context of ship dismantling. The authors concluded that these benefits can be realized if, and only if, both public and private actors work together.

The work by Camañes et al. (2024) presents an eco-design methodology, based on the adaptation of the LCA method to the changing design environments, the customization of environmental databases to the product of the company, and the development of a software tool for its application during early design phases. Firstly, the LCA methodology has been adapted to make it easier to be applied during the design process, when limited data are available (e.g., product structure, partial weight, materials, and tentative processes), and generally when no advanced knowledge on LCA is possessed by designers. Secondly, the databases were customized to only include datasets related to the products of the company that implement the proposed method (e.g., specific materials used by the company, or manufacturing processes usable with the selected materials). Thirdly, a dedicated software tool that integrates a data input module, the customized databases, and a results module was developed to favor the implementation of the proposed method in real industrial contexts. The case study, which focused on a manufacturer of LED weatherproof luminaires in Spain, allowed the authors to demonstrate the effectiveness of the proposed methodology in supporting LCA implementation during the early stages of design.

3. Conclusions

The works collected in this Special Issue, ‘Product Eco-Design in the Era of the Circular Economy’, provide a comprehensive exploration of the challenges and opportunities in designing sustainable products that align with CE principles. Through diverse methodologies and case studies, the contributions highlight several key themes central to advancing eco-design and identify gaps where further research and innovation are needed.

A prominent theme emerging across the papers is the importance of education in eco-design and CE practices. As the principles of CE require a paradigm shift in how products are conceived, designed, and managed throughout their lifecycle, education is recognized as a fundamental enabler. Several studies emphasize the need to incorporate CE concepts into engineering and design curricula at universities and professional training programs within industries. By embedding eco-design principles, lifecycle thinking, and circular strategies into early education, future designers and engineers will be better equipped to address sustainability challenges. Additionally, lifelong learning opportunities for professionals are crucial to ensure that they remain adept at applying the latest tools, guidelines, and methodologies.

Another emerging theme is the need for structured eco-knowledge collection and management within companies. Several papers underscore the value of knowledge-based systems that systematically collect, manage, and disseminate knowledge related to eco-design and CE implementation. For instance, design guidelines tailored to specific industries or products can provide practical frameworks for addressing sustainability goals. Knowledge-based tools and decision-support systems are highlighted as powerful mechanisms for fostering collaboration between product designers, material engineers, and recycling stakeholders. Such knowledge-based systems not only enhance the efficiency of design processes, but also ensure that circularity considerations are embedded at every stage of the product lifecycle, from material selection to end-of-life management.

A recurring topic across this Special Issue is the importance in developing and applying dedicated tools for eco-design. The integration of tools, such as LCA methodologies, circularity indicators, and software for design optimization, are seen as enablers in bridging the gap between theoretical eco-design principles and their practical implementation in industrial settings. These tools support designers in evaluating environmental impacts and circularity performance early in the design process, even when limited data are available. Several case studies illustrate the effectiveness of such tools in sectors ranging from packaging, consumer electronics, and facial masks to ship recycling and LED luminaire manufacturing. By providing actionable insights, these tools support designers in making informed decisions that align with both functional requirements and sustainability goals.

These findings are also aligned with the recent topics investigated by the two editors of this Special Issue [13,14,15].

The findings from this Special Issue also shed light on significant barriers and opportunities for further research and innovation. The application of CE principles often requires interdisciplinary collaboration to address technical, economic, and social challenges comprehensively. For instance, the design of recyclable composite materials, explored in one of the articles, highlights the need for harmonized efforts across material science, industrial design, and recycling infrastructure. Similarly, the integration of CE principles into complex systems, such as ship recycling, reveals the necessity for standardized metrics, policy incentives, and cooperative frameworks between public and private stakeholders.

Future research directions and interesting topics are identified in this Special Issue. Firstly, there is a need to refine and expand eco-design methodologies to encompass a wider variety of product categories and industrial contexts. This includes developing circularity strategies for dissipative and consumable products, which currently pose significant challenges due to their inherent material losses during use. Secondly, improving the usability and accessibility of eco-design tools is essential for their broader adoption. Simplified tools and methodologies that require minimal prior knowledge can help small- and medium-sized enterprises (SMEs) overcome resource constraints and adopt sustainable practices. Moreover, there is a pressing need for research that addresses the social dimensions of the CE. Consumer education, behavioral insights, and community engagement are all vital for the success of circular business models. Studies on how design can influence consumer behavior, foster sustainable consumption patterns, and build trust in recycled or refurbished products are particularly relevant.