This thesis applies the Safe and Circular by Design (SCbD) methodology and the MAPSSS (Mapping Assessment for Product Substance Safety and Sustainability) tool to B2B office task chairs, demonstrating how material safety can be integrated into the design process from early stages. The research was motivated by a gap in current practice: substances of concern in products are addressed almost exclusively through regulatory compliance, while the product design perspective remains largely absent.

The study follows the four steps of the MAPSSS tool.
Step 0 mapped the full lifecycle of a median office task chair, constructed from physical teardown evidence and material composition data from the Declare Living Future database.
Step 1 identified TCPP (tris(1-chloro-2-propyl) phosphate) in polyurethane foam as the priority substance of concern, with the use phase carrying the highest concern scores across both human health and environmental pathways, and end of life carrying the second highest.
Step 2 developed three design concepts, each corresponding to one of the SCbD strategies:
The Avoid concept removes TCPP and foam entirely through an SLS-printed nylon construction,
The Reduce concept retains the standard foam architecture but intercepts TCPP migration through an integrated active carbon filter system
The Control concept removes foam from components where it is not functionally necessary, substitutes aramid textile, and combines this with controlled off-gassing during manufacture and biophilic-supported filtration during use.
Step 3 assessed the three concepts against the reference chair, showing that each strategy shifts the hazard profile across the lifecycle rather than removing it, and that each depends on conditions outside the product itself to deliver its intended reduction.

The research draws on twenty expert interviews conducted across the full office chair value chain, a physical teardown of two second-hand chairs, and a feedback session with NPK Design. The findings show that chemical safety and circularity are structurally deprioritised across the industry, that the MAPSSS methodology adds a complementary substance-of-concern lens to existing sustainability practice, and that the methodology’s principal barriers to adoption are the absence of accessible component-level material data, the chemistry knowledge required in Step 1, and the lack of built-in validation mechanisms across the steps.

The thesis contributes a real-industry application of the SCbD methodology and MAPSSS tool, a set of concrete recommendations for the further development of both, and three resolved design concepts that illustrate the range of design responses available when applying the SCbD framework to a product containing a substance of concern. ... Read more

This thesis investigates how additive manufacturing (AM) can be meaningfully integrated into the Philips Personal Health (PH) spare parts ecosystem, with the aim of enabling more repair, supporting circulari-ty ambitions, and preparing for future service and fulfilment models. At the core of the project are three deliverables: a strategic future vision roadmap for AM integration, a part selection framework, and a redesign framework supported by a prototype display. Together, these provide a structured un-derstanding of what is feasible now, what could be feasible next, and what Philips could do to scale AM as a credible complementary spare parts route. The future vision roadmap outlines four horizons, from today’s consumer home printing model through Philips Fixables to long term hybrid fulfilment systems, and identifies the technological, regulatory, market and business model developments required along the way. Findings show that consumer FDM (Fused Deposition Modelling) printing can support only a limited subset of grooming and beauty parts, and that meaningful expansion will depend on the emer-gence of professional printing environments with certified materials and predictable quality. Ultimately, AM could enable Philips to offer “spare parts on demand”, supporting repair and refurbishment far be-yond the lifespan of traditional sourcing. A part selection framework was developed and applied to the full PH consumer replaceable parts (CRP) portfolio. Out of 492 parts, 133 were considered eligible for AM, from which 104 as suitable for consumer FDM printing. Eligibility was strongly constrained by regu-latory classification and material limitations, confirming that near term AM opportunities lie primarily within the grooming and beauty category. The analysis also highlighted organisational gaps in data consolidation, reinforcing the need for Philips to streamline part data to scale AM decision making. To enable scalable redesign capability, a redesign framework and prototype display were created based on the insights from the succesful redesign of four parts from the grooming and beauty portfolio. These tools help designers structure early stage AM decision making and promote a shared way of thinking. User testing showed that the content is clear and valuable for onboarding less experienced designers, though further refinement and broader stakeholder testing are needed. The project concludes that AM is not a replacement for injection moulding but a complementary capability that excels in low volume, on demand, long tail spare parts, especially when traditional sourcing is costly, slow or unavailable. AM’s value lies in enabling repairs that would otherwise not occur and, in the longer term, supporting refurbishment and extended product lifetimes. For Philips, the key implications include clarifying future user groups, consolidating relevant part data, reconsidering the structure of the spare parts portfolio, and deciding how AM redesign responsibilities should be organised. Overall, this project provides Philips with a strategic direction, practical tools and concrete insights needed to position AM as a scalable and service oriented spare parts solution for the future. ... Read more

This study investigates the premature failure of mid-drive e-bike motors and develops a solution to make them more durable. The research direction was motivated by surveys conducted by van Dam (2025) and Wertgarantie (2024), which highlighted that 24.2% of e-bike technical failures involve the motor. When an out-of-warranty e-bike motor fails, the whole bike often gets discarded because the high replacement cost of the motor (over €1,000) makes consumers purchase a new e-bike.

To understand the causes of these failures and address the hypothesis that environmental and thermodynamic factors play a role, a mixed-methods approach was utilized. Qualitative data was gathered through 11 interviews with local repair mechanics and 4 interviews with specialized remanufacturers. Additionally, physical product teardowns were conducted on 9 different mid-drive e-bike motors to analyze their internal architectures and component failure points.

The findings showed that the thermodynamic "breathing cycle" is a cause of e-bike motor durability. As the motor cools, pressure differentials draw ambient humidity past the seals, causing internal condensation that leads to the failure of bearings and electronic components. Recognizing that standard hermetic seals cannot stop this cycle, the design vision shifted from passive water sealing to active internal humidity management. As a result, a modular Desiccant Cartridge filled with indicating silica gel has been developed to absorb internal moisture and prevent condensation on components. The cartridge is filled with 10 grams of silica gel and has to be replaced every 2 years with heavy use.

We conclude that the Desiccant Cartridge concept works theoretically to avoid condensation, but it has not yet been physically tested in practice. Important limitations of this study include the lack of detailed OEM data regarding component failure rates, which necessitated a reliance on qualitative field reports and third-party surveys. A suggestion for further research is to conduct user experience testing to investigate the willingness and confidence of e-bike owners to perform DIY repair and maintenance using these cartridges. ... Read more

The increasing adoption of e-bikes has resulted in a growing number of electric motors being produced, used, and eventually discarded. These motors are high-value components, yet they are often poorly repairable. When a motor fails, it is usually replaced rather than repaired, even though more than half of the failures are caused by mechanical components that are theoretically repairable. It is not viable for bike mechanics to open or repair motors themselves, but they play an important role in monitoring and diagnosing problems. At the same time, their ability to assess the internal condition of e-bike motors is limited by closed systems, software-based diagnostics, and a lack of mechanical insight.

This project explores how bike mechanics could be better supported in the transition towards a more circular e-bike motor system. The research combines expert interviews, system analysis, technical teardowns, disassembly mapping, and exploratory testing to understand current barriers to repairability and identify opportunities for improvement. The findings show that mechanical failures, particularly in bearings and gears, occur frequently and are often technically repairable. However, limited ability to detect and diagnose the right signals means that motors are often not, or only at a late stage, referred to revision specialists.

Based on these insights, a non-invasive, vibration-based diagnostic concept was developed. The proposed tool enables bike mechanics to measure vibration signals from the outside of the motor and compare them with baseline data from healthy motors. In doing so, it supports mechanical diagnosis and helps mechanics make more informed decisions about follow-up actions. Prototyping and testing demonstrated a proof of principle that vibration analysis can be used to distinguish between healthy and defective motors.

The project also highlights important limitations of the proposed concept. It depends on the availability of reliable baseline data, a well-developed revision infrastructure, and clear responsibility for software and data management. Rather than presenting a final solution, this project provides a research direction, a technical proof of principle, and a system-level perspective on the role of diagnosis in improving e-bike motor repairability. It offers a foundation for further research and development towards a more circular e-bike motor system. ... Read more

This dissertation examines how bio-based design practices can contribute to a post-growth societal transformation by rethinking the material, social, and cultural dimensions of technological production. It begins from the recognition that escalating environmental crises expose the limitations of sustainable design: while sustainability-oriented innovation has led to many advances, these remain largely embedded within economies organized around perpetual growth, whose expanding material and energy throughput is incompatible with finite planetary boundaries. Addressing this tension requires a dual transformation: transitioning from fossil-carbon based infrastructures to regenerative, bio-based ones, while simultaneously reorienting society toward modes of living that prioritize wellbeing within ecological limits.

To explore the implications of post-growth thinking for design, I analyze three layers of society – infrastructure, social structure, and superstructure – combining theoretical investigation with practice-based experiments. At the infrastructure level, I consider the political dimensions of material production, and propose convivial materialization as an alternative to the industrial monopoly over how things get made, instead emphasizing localized, regenerative, and autonomy-enhancing modes of production. At the level of social structure, I explore the Commons an economic model to organize technology according to post-growth values. Focusing on carbon sequestration as a critical climate mitigation strategy, I propose the concept of a Carbon Commons, to reframe sequestration as a social process through which communal objectives can be integrated with technical ones. When treated as a commons, carbon sequestration can be designed to simultaneously regenerate ecosystems, meet collective needs and aspirations, while providing the basis for social relations based on reciprocity, shared responsibility, and mutual care. At the superstructure (cultural) level, I challenge the dominant temporal assumptions in design and argue for engaging more-than-human temporalities through two capacities – noticing and care – to embed design practice within ecological contexts and work towards long-term regeneration. Synthesizing these insights, the dissertation positions regenerative design as a practical means of operationalizing post-growth principles in a reinforcing manner.

Together, this dissertation presents a cohesive argument: design can play a transformative role in advancing post-growth futures, but only when it critically confronts the structural drivers of ecological crisis and reorients its material practices toward regenerative, convivial, commons-based, and care-centered modes of world-making. ... Read more

Today, products are purchased, used, and discarded when they become obsolete, damaged, or no longer desirable. This pattern continues to tie economic growth to environmental losses, leading to increased waste, resource scarcity, and other environmental and societal impacts. Transitioning to a circular economy could in- stead support the preservation of the value of resources and products, eliminating waste and pollution. Achieving this transition requires products to be intention- ally designed to fulfill these requirements. For instance, by extending the useful life to maintain the value of products and materials, by making them suitable for reuse, repair, refurbishment, or recycling. While numerous ongoing efforts focus on achieving this, a significant challenge in circular product design has received limited attention: safety.
By overlooking safety in circular transitions, we risk encountering aggravated or unforeseen risks and limitations when implementing circular strategies. Safety should be explicitly addressed in circular product design throughout all stages of the product lifecycle, enabling materials, products, and their components to be safely cycled. However, awareness, information, and methods for designers to address safety in circular product design are currently limited and absent from the literature. This dissertation addresses this gap by developing methods to support designers in developing products that can safely cycle in a circular economy.
This work is a first exploration of safety aspects in the circular economy from a product design perspective. It examines two angles: first, how product design can influence risks associated with product lifetime extension; and second, how it can influence risks arising throughout the product’s lifecycle from the materi- als it contains. We explored these angles through research on designing for safe non-professional repairs and on mitigating the risks posed by Substances of Con- cern (SoC) throughout product lifecycles. We studied non-professional repairs be- cause safety is often cited as the reason for restricting this group from performing them, thereby limiting the potential of this circular strategy. We studied SoC risks across product lifecycles, as SoC can harm human health and the environment, prevent materials from cycling if contaminated, and, if recirculated, reintroduce contaminants, amplifying existing risks. Both topics take the product as the unit of analysis, but the SoC topic also applies a broader lifecycle perspective. Together, they provide complementary perspectives on safety in circular product design.
This dissertation presents five studies that 1) examine how design influences the safety of circular products and 2) present the development of methods to support designers in addressing safety in circular product design. Chapter 2 focuses on design for safe repairs, while Chapters 3 to 6 are dedicated to SoC risks. At the start of this PhD research, the topic of SoC risks in products was largely unexplored. In contrast, safe repairs had been investigated in two previous projects within our research group, which provided a foundation for this work. For this reason, four chapters focus on SoC, and one addresses safe repair... ... Read more

In a predominantly linear economy, premature replacement of consumer electronics accelerates CO₂ emissions, resource scarcity, e-waste, and pollution. Focusing on vacuum cleaners as high-volume small appliances, this project uses consumer behaviour factors as a leverage point to design digital interventions that motivate consumers to repair.

The project, commissioned by Techniek Nederland, operates at the intersection of industry networks and academic research, serving as a bridge between several nationwide initiatives.

Activties were guided by the main research question (RQ): How can a repair platform address consumer needs, integrate stakeholder roles, and improve diagnostics in electronics repair to motivate repair practices?

Five sub-questions further explore category-specific repair challenges, critical consumer behavioural factors, diagnostics journeys, stakeholder dynamics, and intervention prioritisation.

To answer these questions, a mixed-method design approach was employed, combining literature review, expert interviews, product analysis, consumer research, and benchmarking of existing platforms. Insights from these activities were translated into a design vision, objectives and criteria. These informed further ideation workshops, concept development, and platform interventions, which were iteratively refined against the evaluation criteria.
The main outcomes of the project are twofold:
- A research-grounded set of design criteria for professional repair platforms, serving as a reference to inform digital interventions in the repair domain.
- A final platform concept spanning two horizons: a near-term Repair Prompt Studio enabling consumers to build diagnostic prompts and use for external AI tools, and a longer-term RepAIr Platform centralising repair data, adapting diagnostic pathways, and integrating solutions.

The design was evaluated through a user testing and consolidated into a strategic roadmap, outlining actionable steps toward the project’s overarching vision of creating a cultural shift towards repair willingness.

This thesis connects theoretical insights from consumer behaviour research with tangible digital interventions, providing industry stakeholders with actionable tools to enhance current repair practices. ... Read more

This project aims to explore the balance in maintaining durability while redesigning a highly durable, potted electronic product for repair and recycling. The case study analyzes and redesigns both the product journeys and the product architecture of an agricultural antenna.

Stakeholder and field research revealed that the farmer is largely in control of the end of life of the antenna. However, they are often unaware or unmotivated to properly dispose of it. Stakeholders have an opportunity to better inform, guide, and motivate the farmers towards initiating the best-case end-of-life of their antenna.

The repairability analysis first identified the electronic components, namely the PCB and copper wire, as priority parts because of their value and functional importance. The bonding attribute of the potting material completely prevents any access to those priority parts for repair. A shredding experiment further exposed the harmful effects of the potting material in the recycling of the product, as it prevents almost any liberation of the copper components during recycling. Additionally, discussions with recyclers and existing recyclability guidelines helped assess the theoretical and practical recyclability, as well as the liberation during recycling, of the other materials in the antenna.

To explore the tensions between the repairability, recyclability, and durability requirements found during the analysis, the redesign section presents alternatives for improving the circularity of the product’s architecture. A hardware subscription model and recycling additions to an already existing software interface are presented to address the farmers’ lack of recycling knowledge. Finally, a prototype combining alternatives in the product architecture categories is shown and evaluated against the old prototype and the new durability, repairability, and recyclability requirements. ... Read more

The goal of this thesis was to provide designers guidance in designing their yet-to-be designed products that contain injection moulded parts in a way that allows for interchangeable, functionally equivalent spare parts produced with additive manufacturing in the future. The project was scoped to stereolithography as the additive manufacturing technology, focusing on geometrical and mechanical aspects of product design. The result of the thesis is a newly developed guide, referred to as the ‘form factor optimisation guide’. This guide was developed by analysing literature and conducting various case studies.

Two newly developed approaches are part of the form factor optimisation guide, referred to as the ‘geometry-based part coupling approach' and the ‘form factor definition approach’. A designer can compose a product architecture map using the geometry-based part coupling approach to map the relationships of coupled parts. Parts are considered coupled when they influence each other’s geometry. The product architecture map, along with the list of requirements, is used to define the ‘form factor’ of a part. This form factor is the design space and non-design space for the part's geometry. Using the form factor, the designer can optimise the part for production with injection moulding and stereolithography. It may occur that the form factor does not allow the designer to cope with the limitations of each manufacturing technology. In this case, ‘reciprocity’ is applied. Reciprocity is the term that is used to describe the process of going back and forth between the designs of coupled parts and their requirements. Reciprocity is applied until the form factor allows for interchangeable, functionally equivalent parts produced with injection moulding and stereolithography. ... Read more

Noise pollution is a growing concern in homes and workplaces, making acoustic solutions more important than ever. This project explores the potential of corn cobs (an agricultural by-product) to create sustainable acoustic panels. The goal is to offer an alternative to conventional soundproofing materials that is both eco-friendly and practical for real-world use.

Traditional acoustic panels are often made from synthetic materials like mineral wool, foam, or fiberglass. While effective, these materials come with environmental downsides, including high carbon footprints, waste generation, and, in some cases, the release of volatile organic compounds (VOCs) that can affect indoor air quality. This project takes a different approach by repurposing agricultural waste into a functional and circular product.

To test the concept, a prototype panel was developed. It measures 260 cm long, 30 cm wide, and 3 cm thick, designed to fit into U-profiles that attach to a floor-to-ceiling frame. The sound absorption coefficient was measured at approximately 0.35, meaning it provides some noise reduction but still has room for improvement. Mechanical tests revealed that the panel’s bending and tensile strength are lower than standard requirements, highlighting the need for a stronger or more suitable binder.

Despite these technical challenges, the project has promising advantages. Corn cobs are widely available and inexpensive, making them a cost-effective raw material. The panels support a strong sustainability narrative, helping brands improve their eco-friendly positioning. They also do not emit VOCs, making them safer for indoor use. Aesthetically, they have a neutral, modern appearance that can suit various interior styles, and their customizability allows for different design possibilities.

However, there are still some limitations. The natural inconsistencies of the material, along with its sensitivity to moisture, could affect long-term durability. Some users might also question its strength, especially compared to established alternatives. The texture of the panels may not appeal to everyone, and while the production process is scalable using hydraulic pressing, setting up large-scale manufacturing could be costlier than expected. Additionally, competing with well-known brands will require strong market positioning.

To make the product commercially viable, key aspects such as cost, regulations, and consumer demand need further evaluation. The main target audience includes first-time homebuyers and renovators who prioritize sustainability, but the panels could also be applied in commercial spaces. The next steps will focus on improving strength and moisture resistance while maintaining environmental benefits.

This project demonstrates how agricultural waste can be transformed into useful, sustainable materials. While further refinements are needed, corn cob acoustic panels have the potential to become a real alternative to conventional options. By balancing sustainability, function, and design, they could contribute to a more circular and environmentally responsible construction industry. ... Read more

This thesis presents the design process of a novel noise barrier design made from horizontally arranged, decommissioned wind turbine blade material.

To address climate change challenges worldwide, wind power is increasingly being adopted. The wind turbine blades (WTBs) used for them are decommissioned after 20-25 years, at which point a problem emerges: the complex material composition makes that current end-of-life options result in the loss of material value without regaining significant economic value. The aim is therefore to structurally reuse WTB material in applications that preserve material integrity and prolong its lifetime. Scalable and long-lasting noise barriers are consequently identified as a fitting opportunity. This thesis focuses on horizontal arrangements of WTB material for use in a noise barrier as this is underexplored and will more closely resemble conventional building materials.

However, due to the variable curved shapes of WTBs, seamless assembly in noise barriers becomes challenging. Especially since gaps compromise the noise attenuation of a noise barrier. The proposed design is a solution to that challenge. It configures WTB panels in modular cassette-panel-cassette sections that allow for tackling alignment issues and can be easily (dis)assembled on frame structures. It attenuates noise by reflecting sound waves into the sky off of tilted, continuous front panels. A second column of panels further reduces sound transmission behind the barrier. Continuity and aesthetic harmony of the barrier in its surroundings is aimed for by use of climbing plants and a green colour palette.

The design follows from a process based on research. Led by a vision on durability, modularity and feasibility, ideas are developed into two concepts that are evaluated with input from experts. Subsequently, one integrated concept is further developed through (CAD) modelling, prototyping, testing, simulating, and a survey.

Three research questions are answered throughout this process. To ensure seamless fitting, a parametric model is developed to inform segmentation strategies. It filters out excessively curving parts to retrieve suitable panels. Alternating the orientation of cladded panels and avoiding seams in the road-side surface of the assembly further tackle alignment issues. Analysis of existing noise barriers reveals that mounting and assembly are facilitated by use of modular cassette-based systems. Cassettes can accommodate the WTB panels that contain variable curvature. A prototype is developed to test fastening options, resulting in an adjustable and reversible clamp design that allows for acoustic sealing. The resulting cassette-panel-cassette modules can be pre-fabricated off-location to reduce time spent on-location. Maintaining opportunities for next material lifecycles is found to largely depend on resizing activities. Large panels are prioritized as they can be more broadly reused than smaller ones. Additionally, protecting exposed core materials of sandwich structures (balsa wood and foam) against weathering is important. An explorative test with epoxy coatings provides starting insights to this end.

Overall, the valuable insights in this thesis culminate in a functional, feasible and desirable noise barrier made of WTB material, and highlights areas for further industry research. ... Read more

Achieving sustainability is an important challenge that requires new approaches to the design and production of materials and products. Bio-based plastics offer a promising opportunity in the search for sustainable materials. Derived from renewable feedstocks such as plants and agricultural waste, they offer an alternative to traditional fossil-based plastics. Yet, despite their potential, bio-based plastics are mainly used in packaging and other short-lived products, and the opportunities of using bio-based plastics in durable products remain largely underexplored.

This dissertation explores how bio-based plastics can be incorporated into the development of durable products for a circular economy. It examines the opportunities, challenges, and decision points faced by product developers when working with bio-based plastics, moving beyond simple material substitution to rethinking product design and development. The dissertation provides practical guidance to support product developers in making informed, sustainable choices when developing durable, circular products with bio-based plastics. ... Read more

This dissertation sets out to strengthen the role of repair within the circular economy by filling critical knowledge gaps in the design and assessment of consumer electronic products. Its overarching aim is to develop design guidelines and evaluation methods that improve fault diagnosis, disassembly assessment and repairability scoring, thereby enabling longer product lifetimes and supporting right to repair policies.

To fulfill this aim, this dissertation combines three complementary research activities. First, an in-depth observational study followed 24 participants, with and without prior repair experience, while they diagnosed faults in four common appliances and verbalized their reasoning. This qualitative data was supported by video analysis and post-task interviews. Second, more than ten thousand timed repair actions carried out by professional technicians on fifty-two appliances fed a quantitative model that links specific disassembly and reassembly operations to realistic proxy times, yielding the DaRT model (Disassembly and Reassembly Timing). Third, two successive studies compared six widely used repairability scoring systems against state-of-the-art design literature and then tested three of them empirically on sixteen products, comparing proxy-time and step-count approaches and probing best- and worst-case interpretations for each scoring systems.

Findings show that product architecture shapes user success in fault diagnosis more strongly than prior repair expertise. Clear visual or auditory feedback, component visibility, and unobstructed access prompt a direct or “pinpointed” search strategy, whereas hidden fasteners and recessed modules push users toward trial-and-error and early abandonment. Disassembly difficulty emerged as one of the main barriers that makes most people give up the diagnostic task. These insights were translated into a set of design guidelines that extend conventional principles of modularity and accessibility with new emphases on facilitating testing and providing component-level fault cues.

The DaRT model was able to predict real disassembly times for vacuum cleaners, washing machines and televisions with high accuracy while remaining easier to apply than complex methods such as eDiM. By explicitly including reassembly, DaRT provides a fuller picture of ease of a complete repair cycle. Validation against independent product assessment confirms accuracy.

Analysis of existing scoring systems revealed that most scoring systems weigh ease of disassembly appropriately but treat other decisive criteria such as spare-part price, diagnostic information and safety too sparsely or with ambiguous wording. In scenarios where repair is deemed infeasible or too expensive, the research demonstrated that the current scoring systems do not accurately represent the actual repairability of products. To address this issue, the study proposed the implementation of a limiting factor approach for criteria that determine the feasibility of repair. Proxy-time metrics like DaRT correlated more closely with measured effort than simple step counts, recommending a shift toward time-based assessment in future scoring systems with more weight on physical repairability of products.

This dissertation advances scientific understanding of repairability by emphasizing the critical yet underexplored role of fault diagnosis within product design and user interaction, presenting a holistic perspective that bridges technical elements with user cognition and behavior. It refines existing repairability assessment frameworks by highlighting gaps such as inadequate coverage of diagnostic aids and inconsistent weighting criteria, proposing improvements that enhance assessment validity and reliability. Moreover, this research introduces the DaRT proxy time model as a practical, accurate alternative to complex existing metrics, beneficial across diverse product categories. Societally and environmentally, this work supports the right to repair movement by empowering users to confidently diagnose and repair devices, thereby reducing electronic waste, informing purchasing decisions, and enabling manufacturers and policymakers to create genuinely repairable, sustainable products aligned with broader climate and circular economy goals.
... Read more

Throughout its evolution, our industrial economy has hardly moved beyond the linear consumption model of ‘take-make-use-waste’. Alternative systems, such as the circular economy, are suggested to overcome the challenges of the linear economy. It proposes a restorative way of consumption where materials, products and parts are kept longer in use and no waste is generated. Repair helps to slow down the resource loops, with the added benefit that the required investments are lower than for other recovery options. However, spare parts may not be available when the production of the products ceases as it is difficult to predict how many spare parts are needed and storing them in warehouses can be costly. To make spare parts more generally available, they could be produced with additive manufacturing. Printed spare parts can be stored online instead of in a physical inventory, reducing delivery time, costs, emissions, and material waste. However, to fully optimise printed spare parts, a better understanding is needed of the design considerations that are involved.

In this dissertation, we explore how additive manufacturing can be used to produce plastic spare parts for the repair of consumer products. By reviewing the repairs of consumer products in repair café’s, we estimate that around 8-29% of plastic spare parts are currently suitable for additive manufacturing. As most parts are currently unsuitable for additive manufacturing, the design of these printed spare parts needs to be aligned with the capabilities of the technology. This requires a better understanding of the specific design considerations. We need to find what design aspects are suitable for the use of additive
manufacturing and which are more difficult. This will help us to determine the design complexity and what the biggest design challenges will be. Also, we investigate how to design parts that facilitate the use of additive manufacturing. Since parts can be designed by either the consumer or the manufacturer, it is important to distinguish between design in consumer self-repair and in manufacturer-enabled professional repair. These design perspectives are explicitly included in this dissertation.... ... Read more

This graduation project focuses on enhancing the sustainability of the Laerdal suction canister by developing a new reusable canister design for the LCSU, with a design emphasis on personal use. The design report comprises eight chapters, detailing the design research, iteration, and final proposed design. ... Read more

This thesis investigates how electronic products can be designed for effective recycling, which can reduce the demand for critical raw materials and mitigate environmental and human health risks through the safe removal of hazardous substances. In collaboration with an electronics recycling facility, this study provides practical insights into e-waste recycling through a shredding experiment. By conducting a shredding experiment with four brands of smart TVs the influence of product and part characteristics on the liberation and separation of materials are studied. The insights of this experiment, with a specific focus on connections and materials, are incorporated into Design for Recycling (DfR) guidelines and introduces a novel method to assess the tensions between repairability and recyclability, called: Recyclability Maps.

Key findings include the identification of connections that influence the separation of materials, such as the high liberation degree of snap-fits and the complex behaviour of screws and adhesives. This study demonstrates the critical role of product design in enhancing the recyclability of products and reducing its environmental impact. The developed DfR guidelines offer practical guidance for designers, integrating theoretical insights with empirical data from the recycling experiment. The Recyclability Map method provides a structured approach to evaluate how design choices affect the repairability and recyclability of a product. With this method the smart TVs were analysed on the tensions between these two circular design strategies.

The thesis concludes that effective integration of circular design strategies requires careful selection of connections and materials during the design phase, emphasizing the importance of informed design decisions to promote sustainability. ... Read more

The study discusses the challenges posed by substances of concern (SoCs) in products, emphasizing the need to address them within the framework of a circular economy (CE). It introduces the Safe and Circular Design (SCD) method as a potential solution but notes its lack of practical testing. The study focuses on implementing the SCD method in addressing indium tin oxide (ITO) within a liquid crystal display (LCD) monitor, highlighting difficulties due to limited data on SoCs and strategies for their management. An ex-ante life cycle assessment (LCA) compares ITO and an alternative, revealing environmental impacts and challenges in evaluating toxic trade-offs. The application of the SCD method to the LCD case identifies insights and challenges, emphasizing the importance of data availability and multidisciplinary collaboration for safer and sustainable product development. The study recommends refining the SCD method and conducting further case studies to assess its effectiveness across different scenarios. It underscores the need for enhanced data transparency and collaboration among stakeholders to advance safe and sustainable product design. ... Read more

This graduation project presented the development of a new Photovoltaic-Thermal panel (PVT) module design, aimed at addressing sustainability challenges in conventional solar panels. The research focused on improving repairability and recyclability by replacing the standard ethylene-vinyl acetate (EVA) laminate with a liquid encapsulant. This transformation enhanced the module's thermal stability and light transmittance and innovatively converted the panel into a pioneering photovoltaic-thermal (PVT) system. Experimental prototypes, conducted at the Photovoltaic Materials and Devices - TU Delft, demonstrated the feasibility of this concept. The outcome of this graduation project, conducted for Biosphere Solar, laid a robust foundation for future developments in sustainable solar energy solutions. ... Read more

Plastics have become indispensable in modern life due to their versatility and affordability. However, their widespread use has resulted in far-reaching environmental damage, including the accumulation of plastic waste, fossil fuel depletion, and significant greenhouse gas emissions. Bio-based plastics have been proposed as a sustainable, circular solution to the environmental issues associated with plastics. However, bio-based plastics are not implicitly sustainable or circular. These aspects are influenced by how a plastic is produced and how it is recovered at end-of-life, implying that careful attention needs to be paid to material development and product design. This thesis explores the sustainability and circularity of bio-based plastics by looking at: how they are perceived by value chain actors, potential recovery pathways in a circular economy, and environmental impact.


Although bio-based plastics have the potential to be sustainable, the emissions associated with producing them depend heavily on the biomass sourcing. At the same time, bio-based plastics are not de-facto biodegradable and thus efficient recovery at end-of-life needs to be guaranteed. Circular product design with bio-based plastics requires careful consideration of biomass sourcing and recovery. Although much information regarding these aspects is still missing, the research presented in this dissertation provides some guidelines for circular product design with bio-based plastics. In order to reduce environmental impacts, bio-based plastics should be produced with agricultural by-products or with biomass types with a high conversion efficiency. Biomass for bio-based plastics should be cultivated with minimal use of land, water, chemicals and fossil fuels. Environmental impacts can be reduced further by using renewable energy in the production process. Product designers should also consider what recovery pathway they want to target at end-of-life of a product. The plastic composition and product architecture need to reflect the targeted recovery pathway. ... Read more

Thermoplastic composite materials are increasingly used in aircraft construction due to their high-mechanical properties, toughness, rapid processing rates and reprocessing possibilities at their end-of-life. In the production thermoplastic composite parts, 10-40% of the material remains unused, so-called production waste. Despite being a high-performance material that can be re-processed, real-world applications of the material into structures or products are lacking. This research explores how the thermoplastic composite production waste material can be utilised by designers and engineers, by demonstrating its use in a design process of new applications. This exploration resulted in the design of a structural member, that can be tailored to a specific function, and a design of a pedestrian bridge, which aims to stimulate the creative use of the material. By evaluating the design process, a framework is proposed which engineers and designers can utilise to design new applications from composite waste material. ... Read more