The sharing economy offers an alternative to traditional ownership, but most peer-to-peer platforms struggle with the same problem: users try them once and do not come back. Peerby, a Dutch platform for borrowing and renting items locally, is a clear example. Despite sufficient supply on the lender side, the platform keeps losing borrowers after their first experience. This thesis, conducted in collaboration with Peerby, investigates why that happens and proposes a design intervention.

This project follows the double diamond method (Design Council, 2019). The research phase examines the retention problem through four complementary lenses: a 5C analysis, a literature review on behavioural drivers in the sharing economy, semi-structured interviews with eight borrowers, and an online survey (n=82). Together, these lenses converge on a single finding: the primary barrier to retention is not physical effort, sustainability indifference, or social awkwardness. It is mental effort. The uncertainty of not knowing whether an item is available, whether someone will respond, and how to coordinate a pickup creates a cost that outweighs the benefit of cheap access. This dynamic is framed as the value-effort imbalance.

A co-creation session and a strategic alignment meeting with Peerby's CEO confirmed the design direction: operational predictability. This meant moving away from Peerby's original neighbourly chat model towards a more structured system, which is a significant shift for a platform built on informal community exchange. The goal is to make borrowing feel as reliable as buying from a webshop, without losing the human character of peer-to-peer exchange entirely. Three lender interviews during the design phase validated concept feasibility, as any change to the booking flow inevitably affects both sides.

The resulting concept, Peerby Direct, replaces the current chat-based coordination model with a structured booking flow. Borrowers select time slots, the system contacts lenders with a countdown timer, and if no one responds in time, the request automatically moves to a backup lender. A flexibility bar shows borrowers how their input affects their chances of a match. Lenders participate on their own terms through optional response commitments, and faster responders are rewarded with higher visibility through a Perks system. A secondary concept, Peerby Pouch, addresses the handover moment through a lockable bag that enables fully asynchronous exchange.

Peerby Direct was validated through prototype walkthroughs with nine participants and an online survey (n=68). 76.5% of survey respondents preferred the new system over the current chat-based model, and 70.1% indicated they would be more likely to return to a sharing platform that works this way. Backup willingness reached 88.2%. The walkthroughs confirmed that all participants could complete the booking flow independently, though several mechanisms require further refinement to become fully self-explanatory.

The thesis concludes with a phased implementation roadmap. Peerby Direct forms the foundation, followed by the Peerby Pouch for asynchronous handover, a centralised Rentmeester Hub, and a delivery option. Together, these form a four-horizon strategy for reducing coordination effort across the entire borrowing experience.
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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 Dutch energy system is in transition. As the share of solar energy increases and net metering stops in 2027, households are being called upon to play a more active role in managing their own energy. Yet most current solutions are built around technology, not the people using them.

This thesis explores how design can help bridge that gap by guiding households in using their home battery more intelligently, aligning personal goals with system needs.

Conducted in collaboration with Vattenfall, this graduation project investigated how a behavioural, user-centred approach could transform the home battery from a technical product into an adaptive energy system.

Through extensive research across system, household, and user levels, the main barriers in the home battery journey were identified. The project then zoomed in on the use phase. Four key barriers emerged: the energy system does not speak the user’s language, fails to become part of daily routines, offers unactionable information, and treats all users the same. These four barriers shaped the core design challenge.

To address this, the concept is grounded in behavioural design. The Fogg Behaviour Model, the Transtheoretical Model of Behaviour Change (TTM), and the HOOK model were used to structure a strategic approach to behaviour change. Central to this is the behaviour loop; a cycle of trigger, action, feedback, and reinforcement, which served as both the lens and backbone for concept development.

Through interviews, behavioural mapping, and system-level analysis, the central opportunity was identified: to create a smart, adaptive digital layer around the battery that supports more conscious energy behaviour over time.

The outcome is Loop: a household-centred energy system that learns from the family, adapts to their situation, and motivates smart energy action through personalised feedback and stimulation. Two core system components were developed in detail:
1. The onboarding and learning system, which helps Loop tailor its guidance to each household
2. The motivation system, which reinforces helpful behaviour through feedback and stimulation.

The concept was refined through iterative sessions with Dutch families, internal Vattenfall stakeholders, and behavioural scientist Dr. BJ Fogg. The resulting system balances personalisation with clarity and aims to lower the threshold for smart energy assets in the home both now and in the future.

Loop is designed not only as a proposition for today’s battery users, but as a scalable logic for smart energy behaviour across different user segments, assets, and contract types.
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Small household appliances (SHA) are a major part of e-waste, yet many repairable devices still get discarded. This study looks at why consumers—especially 18-34-year-olds with higher education—aren’t repairing their stuff. Using Social Practice Theory (SPT), it breaks repair down into three parts: images (social norms and emotions), stuff (tools, product design, and spare parts), and skills (repair know-how).

Research shows that while many people are willing to repair, they see it as too hard, time-consuming, or simply not worth it. They lack the right tools, struggle with fault diagnosis, and don’t know where to start. Manufacturers set consumers at a disadvantage, making repairs harder with proprietary parts and poor access to manuals.

To address these issues, a design intervention was developed that seeks to lower psychological and practical barriers to repair. This intervention includes a service model that provides structured fault diagnosis strategies, essential tools, and guidance to consumers. The goal is to make repair more accessible, engaging, and socially accepted within the target demographic. The proposed solution was evaluated based on feasibility, user acceptance, and potential impact on repair behavior. Results suggest that interventions combining practical support with social reinforcement can significantly increase repair engagement.

This research contributes to the broader discussion on sustainable consumer behavior and circular economy principles by demonstrating how design strategies can influence repair propensity. Future studies could further explore policy implications, industry cooperation, and scalable interventions to enhance consumer participation in repair practices. ... Read more

This thesis focuses on developing a centralized dishwashing service with the goal of reducing the amount of disposable tableware waste generated at Avinor Oslo Airport. Moreover, the project aims to help Avinor Oslo Airport achieve its objective of becoming a zero-waste airport by 2030.

The research process followed the Triple-diamond model, facilitating a structured approach through mainly three phases: Understand, Ideate, and Develop. The ‘Understand’ involves the study of the literature review, analysis of existing practices, field research, and stakeholder interviews to gain an understanding of the context. During the ‘Ideate’ phase three concepts were developed and evaluated through iterative testing and feedback. Finally, at the ‘Develop’ phase, the final concept, Green Circles, is developed. Green Circles is a centralised dishwashing service for reusable takeaway containers, that allows passengers to drop the containers at drop-off machines at the boarding gates and airport exists.

The implementation of Green Circles is expected to significantly reduce single-use tableware waste at Avinor Oslo Airport. The study highlights the importance of stakeholder engagement, convenient passenger experience, and efficient operational integration. Broader implications suggest that similar services could be adopted in other airports, contributing to the aviation industry’s sustainability efforts, such as those proposed by TULIPS. ... Read more

This research project explores opportunities for EcoWorld to expand their product portfolio beyond mere recycling. The initial goal was to investigate potential products that could improve the living conditions of local communities in Watamu, Kenya, using collected plastic waste. EcoWorld, a local non-profit organization, aims to ignite the plastic recycling economy in Watamu by creating dynamic value waste streams and empowering women and youth as drivers of this economy. However, they face challenges in moving from recycling to circular design practices and in identifying suitable products for the local communities.

The research begins by defining the local context and identifying key stakeholders. It reveals a significant plastic waste problem in Watamu and inadequate living conditions for the local communities. While there is a growing understanding of the potential of collecting and recycling plastic waste, a knowledge gap hinders progress towards more circular practices. The research clarifies what circular practices mean in the local context, centering on creating products from plastic waste that offer enhanced social benefits to end-users while managing the entire lifecycle of these products. It explores EcoWorld’s potential to build a business around this approach and develops a framework for integrating circular practices into local product production. Integrating local end-users into the design process emerged as a key opportunity to create value, understanding, and awareness, ensuring proper waste management and slowing down the resource loop.
A four-week field research in Watamu engaged these various stakeholders in the design process. Observations and interviews with EcoWorld employees highlighted the potential for new technologies to move beyond recycling and the openness to raising community awareness. Creative sessions with local communities provided insights into their perspectives on plastic pollution and their needs for improving their living conditions. While there was interest in using plastic waste materials, trust in these materials for structural improvements, like bricks for houses, was lacking. However, there was significant interest in improving household cleanliness through storage solutions.

Based on these insights, a cabinet design was developed during the design phase together with the local end users. The design focuses on practicality and simplicity to fit the local market, emphasizing functionality and ease of use. The production process was kept simple with minimal tool requirements to ensure feasibility for local production at EcoWorld. The design aligns with the established circular framework, ensuring proper handling of the product at its end-of-life, thereby slowing down the resource loop.

Finally, a transition model was created for EcoWorld’s future growth. An implementation plan for the current product includes the necessary tools and machines for successful production. The transition model is based on building trust among end-users as they become familiar with using plastic waste materials for products and actively participate in the emerging economy. This involvement will enable EcoWorld to expand their product portfolio further and focus on proper waste management in the future, creating jobs and income for women and youth in Watamu, igniting the local plastic recycling economy.
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This Design for Interaction master thesis is focussed on the development of a design intervention to encourage consumer behaviour towards DIY repair and upgrading of furniture. The project was carried out in collaboration with the Behaviour Insights Team of the Ministry of Infrastructure and Water Management and Het Groene Brein.

Problem background:
Furniture is a product category which causes a large environmental impact due to the materials they contain and consumers’ current replacement behaviour. In the Netherlands, over half of the large amount of disposed furniture pieces have not reaching the end of their lifespan (Koch & Vringer, 2023). Increasing repair and upgrading behaviour can extend the life of damaged or undesired furniture pieces and thereby reduce environmental impact.

Research & design goal:
Literature research, generative sessions, a survey and expert interviews were used to determine how a design intervention can most effectively contribute to the desired behaviour change. It was concluded that the design should support 18-35 aged, high income, high education consumers, living in the big cities, to ...

1. … make a plan with a desired outcome for ...
2. … together perform ...

... DIY repair and/or upgrade activities for furniture from the low/medium priced segment made from wood and/or textile and foam in 2024.


Design proposal:
The outcome of this master thesis is a design intervention named ‘Opknappers,’ a proposal for Intergamma (the umbrella organization of Karwei and Gamma). The proposal includes DIY cards and an exposition showcasing and explaining repair/upgrade possibilities in the physical shops. Additionally, a concept for the Opknappers app has been developed, which allows consumers to visualise upgrade options for their own furniture. Finally, a plan was made for using Intergamma’s websites and social media to support consumers in the DIY process. The final design was evaluated with customers and employees of Intergamma, and final improvements and recommendations were made.
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This report delves into the intricacies of sustainable consumer behavior, in the context of Schiphol airport. Schiphol airport is a large airport with large numbers of passengers. These passengers also create waste, which is discarded of. Schiphol has the aim to be zero-waste by 2030.
PET bottles and cans could be seen as a big contributor in the waste streams of Schiphol. This was concluded from research that was executed by TULIPS.
An opportunity for this project was found, as PET bottles and cans are a great option for recycling. This means that ideally these beverage containers should have their separate waste stream. Drawing upon Fogg’s behavior model (2009) as a foundational framework, design opportunities could be found. The model proposes that behaviour is a combination of three key factors: motivation, ability and triggers. In this context, motivation is explored in terms of environmental concerns, while capability is divided into
components such as time, money and physical effort, among others. Triggers, on the other hand, are categorised as sparks, facilitators and signals, each playing a different role in influencing behaviour. The research further delves into practical applications, with a focus on Schiphol and the challenges of PET bottle and can collection. Through a series of brainstorming sessions and idea generation exercises, participants created visual ideas and potential solutions. A final design is proposed which consists of an add-on at the current waste bins at Schiphol, and a campaign proposal. The report concludes with a series of recommendations and insights into what the final design could offer Schiphol as it moves towards a more sustainable future. ... Read more

95 % of all the buildings in the Netherlands rely on natural gas for heat. But in just 30 years, all of these 7 million homes must have said goodbye to gas forever. A complex project, since the alternative to gas, is not a one size fits all solution. There are several options and their feasibility is highly dependent on the neighborhood context. Therefore, municipalities became responsible for the Dutch energy transition. In the earlier energy transition from coal to gas in the 1980s, there were clear economic benefits for residents. Now, despite the record-breaking gas prices, the long-term returns on investments are uncertain while there are many short-term inconveniences.

The technical side of the energy transition tends to overshadow the social dimension. The technical challenges are clear and the path to work on the viable solution is familiar since the municipalities have been in charge of similar infrastructure projects. The social transition, however, is highly dependent on the local situation and requires time. The municipalities have to become the spider that holds the web of stakeholders together to make this complex process work. To help municipalities stay in charge of the energy transition, Stroomversnelling developed Wijkkompas: a process management tool that guides municipalities from ‘Transitie Visie Warmte’ to ‘Wijk Uitvoerings Plan’. Wijkkompas helps municipalities balance the social and technical side of the transition.

On the social side of the transition, participation is a well-known factor that municipalities already take into account. The goal of participation is to make informed decisions together with residents through representation. However, through participation alone municipalities will not be able to reach all seven million households. Therefore the goal of this thesis is to effectively apply the social contagion method to the Wijkkompas tool since social contagion is a process in which the network in the neighborhood will take on the task of activating residents themselves.

Social contagion theory teaches us both information and behavior can be transmitted in a network. Each has its optimal way of traveling through the network and thus has an optimal seeding strategy. For the energy transition, the transmitting behavior with the snowball strategy can be very valuable. Holistically it would be best to separate the participation from the social contagion approach and run a parallel process. However, for the social transition, we rely on volunteers who are busy and scarce. Therefore we propose a six-step model that adequately combines both techniques for a successful neighborhood transition.

The biggest impact can be made when municipalities find the courage to try out this new activation method. The Lopend vuurtje box, designed in this project, uses the principles of social contagion to spread the method through the inter-municipal network. The box invites its receivers to try out the method for themselves through personal assignment, a small experiment, an educational flyer, and by becoming part of the Lopend vuurtje network by sending the box further along its journey through the Dutch municipal network. ... Read more

The Dutch government wants to be circular in 2050. The industry of kitchens and kitchen appliances needs new innovative models of practice to reduce its environmental footprint. As kitchen appliance manufacturer, ATAG Benelux is investing in innovation to create more sustainable and circular business propositions. In a circular economy products and materials have to ‘loop’ back into the system after they lost value, but ATAG’s current system is linear, bringing the appliances to the customer and not returning them. The aim of this thesis is to explore how ATAG can use design to contribute to a circular economy. It is a collaboration between ATAG Benelux and Delft University of Technology. This thesis focuses on the user, their behavior, and their attitudes towards Product Service Systems (PSS's) and Refurbishment as they play a big role in business models. As a case study, the combi-steam oven is used to explore PSS's. The user’s attitude towards refurbishment and circular PSS’s is explored through in-depth interviews. The results reveal several challenges in acceptance for different types of ownership of ovens and show that for the target group of ATAG a system of buy-back is most suitable. The context of retaining value for refurbishment was researched through literature, interviews, and creative sessions. This shows different directions for design to benefit the refurbishment process. The recommended circular business proposition is for ATAG to take back appliances after a use cycle. ATAG Benelux can refurbish its products to save materials and resources. For refurbishment it is important that products retain their value as long as possible. The final design consists of return incentives for users and the Care Assistant. This human centered design stimulates product care, which is a type of sustainable use and handling. The design will influence the user’s behavior in a sustainable way to retain more value, enable efficient refurbishment and a second life cycle. The product care is needed to have a longer product life, or to take back an appliance that is in a better state (than it would be if product care had not been stimulated). With a buy-back system, users are stimulated to return the appliances, rather than let the appliance end up in recycling or worse. ... Read more