S. Dangal
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1
Advancing Repairability in Consumer Electronics
Design Guidelines and Evaluation Methods
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.
...
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.
...
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.
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.
Journal article
(2025)
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Sagar Dangal, Sonia Sandez, Julieta Bolaños Arriola, Jeremy Faludi, Ruud Balkenende
The validity and reliability of four prevalent reparability scoring systems has been investigated by comparing scores of ten smart phones and six vacuum cleaners versus empirically measured repair times, as well as comparing hypothetical ideal and problematic scenarios. Ease of disassembly methods was also assessed for five smart TVs, four washing machines and six vacuum cleaners. The scoring systems studied were the French Reparability Index (FRI), Joint Research Centre Scoring System (RSS/JRC), iFixit, and ONR19202. Overall scores of products across scoring systems were relatively well correlated, indicating a fair amount of overall reliability. However, the variability in scores for the best and worst case of the same product was often larger than the differences between products. Validity was good for products that are easily repairable, but scorecards often failed to score low when repair is infeasible or too expensive. Repair scores greatly depend on disassembly; since some scorecards count numbers of disassembly steps and other scorecards use proxy times, these two methods were compared against empirical disassembly times for five vacuum cleaners, five televisions, and four washing machines. The proxy time method was found to be highly accurate for all three product categories; the steps method was less so. It indicated the relative ease of disassembly well for washing machines, but not for televisions or vacuum cleaners. Finally, this study proposes improvements to scoring methods, including a limiting factor approach and the development of clearer protocols, to ensure the scoring systems are robust, reliable, and can effectively guide sustainable product design.
...
The validity and reliability of four prevalent reparability scoring systems has been investigated by comparing scores of ten smart phones and six vacuum cleaners versus empirically measured repair times, as well as comparing hypothetical ideal and problematic scenarios. Ease of disassembly methods was also assessed for five smart TVs, four washing machines and six vacuum cleaners. The scoring systems studied were the French Reparability Index (FRI), Joint Research Centre Scoring System (RSS/JRC), iFixit, and ONR19202. Overall scores of products across scoring systems were relatively well correlated, indicating a fair amount of overall reliability. However, the variability in scores for the best and worst case of the same product was often larger than the differences between products. Validity was good for products that are easily repairable, but scorecards often failed to score low when repair is infeasible or too expensive. Repair scores greatly depend on disassembly; since some scorecards count numbers of disassembly steps and other scorecards use proxy times, these two methods were compared against empirical disassembly times for five vacuum cleaners, five televisions, and four washing machines. The proxy time method was found to be highly accurate for all three product categories; the steps method was less so. It indicated the relative ease of disassembly well for washing machines, but not for televisions or vacuum cleaners. Finally, this study proposes improvements to scoring methods, including a limiting factor approach and the development of clearer protocols, to ensure the scoring systems are robust, reliable, and can effectively guide sustainable product design.
Design Aspects in Repairability Scoring Systems
Comparing Their Objectivity and Completeness
The Circular Economy Action Plan adopted by the European Commission aims to keep value in products as long as possible through developing product-specific requirements for durability and repairability. In this context, various scoring systems have been developed for scoring product repairability. This study assessed the objectivity and completeness of six major repair scoring systems, to see what further development may be required to make them policy instruments for testing product repairability. Completeness of the scoring systems was assessed by comparing them to the latest literature on what design features and principles drive product repairability. Objectivity was determined by assessing whether the scoring levels in each criterion were clearly defined with a quantifiable and operator-independent testing method. Results showed that most of the criteria in the scoring systems were acceptably objective and complete. However, improvements are recommended: The health and safety criterion lacked objectivity and has not yet been fully addressed. Further research is required to expand the eDiM database, and to identify whether the additional accuracy provided by eDiM compared to disassembly step compensates for the increased difficulty in testing. Finally, assessment of reassembly and diagnosis should be expanded. Addressing these gaps will lead to the development of a scoring system that could be better used in policymaking, and for assessment by consumer organizations, market surveillance authorities, and other interested stakeholders, to promote the repairability of products.
...
The Circular Economy Action Plan adopted by the European Commission aims to keep value in products as long as possible through developing product-specific requirements for durability and repairability. In this context, various scoring systems have been developed for scoring product repairability. This study assessed the objectivity and completeness of six major repair scoring systems, to see what further development may be required to make them policy instruments for testing product repairability. Completeness of the scoring systems was assessed by comparing them to the latest literature on what design features and principles drive product repairability. Objectivity was determined by assessing whether the scoring levels in each criterion were clearly defined with a quantifiable and operator-independent testing method. Results showed that most of the criteria in the scoring systems were acceptably objective and complete. However, improvements are recommended: The health and safety criterion lacked objectivity and has not yet been fully addressed. Further research is required to expand the eDiM database, and to identify whether the additional accuracy provided by eDiM compared to disassembly step compensates for the increased difficulty in testing. Finally, assessment of reassembly and diagnosis should be expanded. Addressing these gaps will lead to the development of a scoring system that could be better used in policymaking, and for assessment by consumer organizations, market surveillance authorities, and other interested stakeholders, to promote the repairability of products.
This paper investigates whether spring-foam technology in an aircraft seat-pan can reduce weight and at the same time provide equal or better comfort. Firstly, through literature studies and using an iterative design process a prototype seat-pan was designed and developed using spring-foam technology. The (dis)comfort of this seat was compared with a standard aircraft seat-pan. Twenty two participants were asked to sit in each seat for 90 min, completing a questionnaire every 15 min. At the end of each seating session pressure map recordings were made of the seat-pans. The results showed that the prototype seat-pan has on average a significantly higher comfort for the first 30 min and at a 60 min recording than the standard seat-pan. The discomfort and long term comfort were not significantly influenced. The pressure distribution on the prototype seat-pan was significantly closer to an ideal pressure distribution than a conventional seat-pan. In addition, the prototype seat-pan had a significantly larger contact area and lower average pressure. The seat-cushion weighs 20% less than the conventional seat-cushion. The study indicates that a seat-pan design using spring-foam technology can be lighter and more comfortable than conventional foam cushion materials. It is recommended to optimize the prototype seat further and conduct long term (dis)comfort studies with a broader variation in subjects’ age.
...
This paper investigates whether spring-foam technology in an aircraft seat-pan can reduce weight and at the same time provide equal or better comfort. Firstly, through literature studies and using an iterative design process a prototype seat-pan was designed and developed using spring-foam technology. The (dis)comfort of this seat was compared with a standard aircraft seat-pan. Twenty two participants were asked to sit in each seat for 90 min, completing a questionnaire every 15 min. At the end of each seating session pressure map recordings were made of the seat-pans. The results showed that the prototype seat-pan has on average a significantly higher comfort for the first 30 min and at a 60 min recording than the standard seat-pan. The discomfort and long term comfort were not significantly influenced. The pressure distribution on the prototype seat-pan was significantly closer to an ideal pressure distribution than a conventional seat-pan. In addition, the prototype seat-pan had a significantly larger contact area and lower average pressure. The seat-cushion weighs 20% less than the conventional seat-cushion. The study indicates that a seat-pan design using spring-foam technology can be lighter and more comfortable than conventional foam cushion materials. It is recommended to optimize the prototype seat further and conduct long term (dis)comfort studies with a broader variation in subjects’ age.
The process of fault diagnosis is an essential first step when repairing a product: it determines the condition of the parts and identifies the origin of failure. We report on how product users go through the process of fault diagnosis in consumer products and the influence of design features on this process. Two groups of 12 participants were asked to determine the fault in a defective product we supplied; the groups differed in their self-reported repair expertise. Four types of products were used for the study: a vacuum cleaner, kitchen blender, radio CD player, and coffee maker. During the experiment, the participants were asked to think aloud to explain their actions and understandings. Afterwards, they were interviewed regarding their experience. The results from the verbal and video analysis provided input for an updated framework of the diagnosis process, describing user actions at each
diagnosis stage. Furthermore, we show that the way a product is designed and constructed (the positioning, accessibility, and visibility of relevant product components) has a significant influence on the success of the fault
diagnosis. An important factor is user experience: product use facilitates signal recognition, while repair expertise facilitates disassembly. However, user experience is still less influential than the product’s design. Based on these findings, we propose a set of design guidelines to facilitate the process of fault diagnosis in consumer products ...
diagnosis stage. Furthermore, we show that the way a product is designed and constructed (the positioning, accessibility, and visibility of relevant product components) has a significant influence on the success of the fault
diagnosis. An important factor is user experience: product use facilitates signal recognition, while repair expertise facilitates disassembly. However, user experience is still less influential than the product’s design. Based on these findings, we propose a set of design guidelines to facilitate the process of fault diagnosis in consumer products ...
The process of fault diagnosis is an essential first step when repairing a product: it determines the condition of the parts and identifies the origin of failure. We report on how product users go through the process of fault diagnosis in consumer products and the influence of design features on this process. Two groups of 12 participants were asked to determine the fault in a defective product we supplied; the groups differed in their self-reported repair expertise. Four types of products were used for the study: a vacuum cleaner, kitchen blender, radio CD player, and coffee maker. During the experiment, the participants were asked to think aloud to explain their actions and understandings. Afterwards, they were interviewed regarding their experience. The results from the verbal and video analysis provided input for an updated framework of the diagnosis process, describing user actions at each
diagnosis stage. Furthermore, we show that the way a product is designed and constructed (the positioning, accessibility, and visibility of relevant product components) has a significant influence on the success of the fault
diagnosis. An important factor is user experience: product use facilitates signal recognition, while repair expertise facilitates disassembly. However, user experience is still less influential than the product’s design. Based on these findings, we propose a set of design guidelines to facilitate the process of fault diagnosis in consumer products
diagnosis stage. Furthermore, we show that the way a product is designed and constructed (the positioning, accessibility, and visibility of relevant product components) has a significant influence on the success of the fault
diagnosis. An important factor is user experience: product use facilitates signal recognition, while repair expertise facilitates disassembly. However, user experience is still less influential than the product’s design. Based on these findings, we propose a set of design guidelines to facilitate the process of fault diagnosis in consumer products
Conference paper
(2020)
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Francesco De Fazio, Juleta Bolanos Arriola, Sagar Dangal, Bas Flipsen, Ruud Balkenende
The Disassembly Map is a modelling method which allows to visually represent the architecture of a product, describing disassembly precedence and dependencies of components and operations necessary for their complete non-destructive removal. It introduced new standard visual elements to communicate the influence of specific design features on disassembly tools, sequences and time. A first iteration of this method was created during a study focused on a single product group, vacuum cleaners [1]. This paper presents a further development, meant to improve its versatility for application in diverse product groups. This was developed and tested by analysing four products (pressurized steam generator, coffee maker, child car seat and washing machine). This study shows the versatility of the Disassembly Map and introduces a new coding of action blocks, that allows the representation of a more extensive range of disassembly actions.
...
The Disassembly Map is a modelling method which allows to visually represent the architecture of a product, describing disassembly precedence and dependencies of components and operations necessary for their complete non-destructive removal. It introduced new standard visual elements to communicate the influence of specific design features on disassembly tools, sequences and time. A first iteration of this method was created during a study focused on a single product group, vacuum cleaners [1]. This paper presents a further development, meant to improve its versatility for application in diverse product groups. This was developed and tested by analysing four products (pressurized steam generator, coffee maker, child car seat and washing machine). This study shows the versatility of the Disassembly Map and introduces a new coding of action blocks, that allows the representation of a more extensive range of disassembly actions.