This thesis looks at the role that Circular Business Models (CBM) play in the development of a Circular Economy (CE) strategy in the aerospace sector. Currently, a transition from a traditional, linear economy to a CE is promoted by the EU and national governments. This thesis contributes to solving the many managerial issues or barriers when making that transition. Using literature review and semi-structured interviews, this case study on Airbus Netherlands discovered that the term CE is badly defined. This causes confusion and misunderstandings when discussing the concept of a CE. Therefore, properly defining a CE should be the foundation of developing a CE strategy. When analyzing the current CBM frameworks, the most well-known are the ReSOLVE and loops framework. The results further indicate that important barriers regarding the implementation of CBMs are technological and monetary challenges. On the other hand, implementing CBMs can have a positive effect on the reputation of the company and increase the chance of sustaining a supply chain. The best CBM strategies involve both a short- and long-term plan that focuses on where the aerospace sector, and Airbus Netherlands specifically can make the most changes like changing designs, swapping materials for less environmentally damaging ones and increase the recyclability of components. The interviews confirm issues found in the literature regarding the definitions and the barriers to implementing CBMs. In conclusion, it is evident that only by the combination of factors like regulations, proper definitions, internal motivation, financial feasibilities and technological developments, CBMs will be able to play a successful role in the developing of a CE strategy for the aerospace sector.

This research explores the intersection between circular economy strategies, critical raw materials (CRMs) and the defence sector, especially focusing on Neodymium-Iron-Boron (NdFeB) magnets. The significance of CRMs in modern defence applications and the associated risks of geopolitical and supply chain disruptions underscore the necessity for a secure supply. Circular strategies are crucial not only for securing a stable supply of CRMs but also for their potential to significantly reduce environmental impacts. This study aims to determine the effectiveness of various circular strategies in securing a stable supply of CRMs, thereby enhancing national security and promoting environmental sustainability. To address the research question, a mixed-methods approach was employed. Secondary data collection involved a review of scientific and grey literature, while primary data was obtained through interviews with experts. The conceptual framework was based on the 9R framework of circular strategies, chosen for its comprehensive coverage of all value retention options, from smarter product use and manufacturing, and lifespan-extending practices to the useful application of materials. This framework was adapted to the context of CRMs. The analysis was conducted using the backcasting method to develop strategic pathways for implementation. From the results, it is clear that NdFeB magnets are crucial to the defence sector due to their exceptional magnetic properties. This makes them indispensable in various defence applications, such as in motors, sensors, and communication devices. The reliance on CRMs like neodymium and dysprosium for the production of NdFeB magnets poses a significant risk due to their limited supply and geopolitical concentration. The study identified effective circular strategies on all 10 levels of value retention. This includes modular design, which facilitates easier disassembly and reuse, and advanced recycling techniques like hydrogen decrepitation, which efficiently reclaims materials. These strategies are already being implemented in the civil sector and can be adapted for defence applications to enhance sustainability and resource efficiency. To implement the circular strategies in the defence sector, barriers and enablers are highlighted on four levels: cultural, regulatory, market and technological challenges. Culturally, the defence sector has a somewhat conservative approach in which operational effectiveness is considered most important. Awareness about sustainability and CRMs can be created through programs, training and role modelling. Secondly, the defence sector is heavily regulated with stringent standards for performance and safety. Therefore, policies are important to ensure that circular practices comply with existing standards and incentives should be created. On the market level, commercial considerations are said to be the hardest challenges which should be taken care of in procurement processes. Lastly, adopting circular strategies involves technological innovations for which investments and development are crucial. Collaboration among various stakeholders is essential to the implementation. A detailed implementation plan is provided including measures to overcome the barriers alongside an indication of time. The research concludes that implementing circular strategies on NdFeB magnets within the defence should be improved as many more benefits can be gained from further implementation especially with regards to lowering dependence on CRMs. By adopting these strategies, the defence sector can not only secure a more reliable supply of critical materials but also contribute to broader sustainability goals. The circular strategies could be tailored to fit specifically into the defence sector by addressing unique challenges and leveraging opportunities.

Components of novel propulsion systems in electric aviation contain materials defined as critical by the European Union: electric motors contain Rare Earth Elements neodymium and dysprosium, and state-of-the-art batteries materials like lithium and cobalt. Such critical raw materials have high supply risks but are crucial for the economy. The demand of all these materials is forecasted to increase drastically in the coming years, which means that the rate of supply might no longer suffice to fill the demand. Circular economy principles have been suggested as a solution. Materials recovered from end-of-life components can secure supplies and reduce the environmental impact of products.

In this research, the implementation of circular economy approaches to address critical raw material demand in electric aviation is studied. According to the developed models, the material demand is negligible in comparison to other industries until 2050. However, as the electric aircraft technologies are still in development, there is a lot of uncertainty around the demand.

Beyond 2050, components will start reaching their end-of-life stage. In this case, a circular strategy considered feasible for electric motors is remanufacturing. After the Rare Earth Element magnets in the motors become obsolete, they can be recycled to recover the critical raw materials. Both hydrogen decrepitation and a combination of hydro- and pyrometallurgical processes can be used to regain materials for magnets in aviation or other applications.

Although circular economy strategies will not be able to significantly reduce the primary material demand in electric aviation by 2050, these can still lower the environmental impacts from production. Additionally, well-established circular practices could address the material demand more substantially in the future, after 2050, if electric technologies are more widely adopted then.

European climate goals to limit global warming to 1.5 degrees Celcius are unachievable in their current form because current green energy technologies needed for the energy transition rely too much on critical raw materials (CRMs). This thesis sought to design something that reduces the negative impact living has on the climate while making living less reliant on critical raw materials. Literature research showed that in the context of buildings, space heating and water heating are the biggest uses of energy in Europe. CRMs are found in many different products in homes, but primarily in electronics. This includes energy generation technologies such as solar panels, energy storage technologies such as batteries, entertainment technologies such as computers, but also other technologies such as boilers, pumps, ventilators and sensors. My research found that the link between human needs and current technologies in homes is a diverse and complicated one. To reduce our energy and CRM use in the built environment, a shift in the consumer’s mindset and a redesign of our technologies are needed. Tiny houses are a great inspiration and show that we can live comfortably with less energy and materials. This thesis looked at tiny houses as a springboard and example of how we can live more consciously and from a mindset of scarcity and balance instead of abundance. As a result, I designed and recorded a podcast that can discuss the complexity of the climate crisis while addressing the complicated human needs behind current CRM-dependent technologies. This podcast hopes to contribute to shifting the mindset and lifestyle of the listener to a more sustainable one.

The mitigation of climate change and the transition to a more sustainable and circular use of resources are two of the largest challenges of our time. To this end, the European Commission proposed the Net Zero Industry Act (NZIA) and Critical Raw Materials Act (CRMA) in March 2023 as further pillars to its Green Deal. While the NZIA focuses on establishing supply chains for net-zero technologies, the CRMA aims to maintain access to the necessary materials. However, these so-called Critical Raw Materials (CRMs), are not only required for net-zero technologies but also for numerous other applications. To ensure their growing demand can be met more sustainably, the European Commission CRMA proposal states that 15% of total CRM consumption in the EU must be satisfied through recycled materials by 2030. In response to the Commission’s proposal and as part of the legislative process, the European Council proposed a more ambitious target of 20% of demand to be satisfied through secondary materials. The European Parliament’s proposal takes a slightly different approach in that it suggests a 45% target for recycling all waste streams, rather than focusing on a set share of consumption.
Given the current dynamic nature of the legislative process, no publicly available literature exploring the extent to which the three proposals can contribute to meeting CRM demand more sustainably could be identified. Hence, the objective of this thesis is to quantify and analyze the implications of each recycling target, leading to the following research question: “How do the Critical Raw Materials Act recycling targets proposed by the European Commission, Council and Parliament compare in their contribution to meeting future demand more sustainably?”. To address this question, a case study on closed-loop neodymium recycling of NdFeB magnets in onshore and offshore wind turbines in Germany between 1989 and 2045 is performed. To map past and expected future neodymium stocks and flows, a dynamic material flow analysis (dMFA) is used. Building on a business-as-usual model without any recycling, explorative scenarios are developed reflecting each of the three CRMA proposals for recycling.
The results reveal that under the expected flow dynamics, the achievement and effectiveness of the targets depends on the time period considered. Because neodymium demand is expected to increase significantly over the upcoming decade, the Parliament’s targets are the most realistic until 2030, given that they are defined relative to actual waste streams. In contrast, achieving the Commission’s and Council’s consumption-based targets is comparably unrealistic, due to the fact that not enough waste streams will be available to satisfy 15 or even 20% of the rapidly growing demand. Extrapolating the targets of the Commission and Council beyond 2030, shows that they are achievable from around mid-2030 onwards. Regardless of the scenario, recycling rates need to increase significantly and rapidly. To meet the Commission’s and Council’s targets in particular, recycling rates of up to 100% until 2035 must be realized. Compared to current recycling rates of below 1%, this appears highly ambitious.
Policy makers are advised to establish targets beyond 2030 and to support relevant stakeholders in creating a recycling infrastructure, both financially and through favorable framework conditions. Future research should explore whether the specific trends observed in this case study also apply to other strategic applications and materials. Moreover, research on how product-life extensions could contribute to decreasing demand for primary materials in the short- to medium-run should be conducted.

Rapid urbanization and a growing world population has exerted unsustainable pressures on the environment, exacerbating climate change through unrestrained material usage and greenhouse gas (GHG) emissions. Since the turn of the century, transitioning to a circular economy (CE) has been seen by policy makers as a potential solution for resource scarcity and climate mitigation. Cities, which possess a high density of human activities, material stock, and waste production, are major contributors to emissions. This is especially true due to the concentration of construction activities in cities – the industry is responsible for 38% of CO2 emissions and 40% energy consumption globally. On the other hand, cities can also facilitate the implementation of circular strategies, thanks to increasing availability of data on space, people, and materials in cities. While the importance of cities for the circular transition is recognized in literature, earlier studies and policy documents on “circular cities” focus on urban governance strategies. Scholars have therefore called for a deeper understanding of the spatial aspects of CE since the late 2010s, engendering the recent integration of spatial disciplines, such as urban planning, regional economics, and geography, into the study of CE. Moreover, the increasing availability of spatial data, especially on the location of material stocks and flows, provides an unprecedented opportunity to develop a data-driven understanding of where, and how far, materials should travel in a CE. This research therefore asks the question, “what determines the locations and scales of closing material loops in a circular economy?” The question was answered in 5 chapters (chs. 3-7), using both quantitative and qualitative spatial analysis methods, as well as present- and future-oriented perspectives. The research scope moves from general to specific, with earlier chapters (chs. 3-6) analysing 10 material types for the whole country of the Netherlands, and later chapters (chs. 6-7) focusing on construction materials in the city of Amsterdam and its surrounding region. Two novel data sources were used throughout the research. Waste statistics from the Dutch National Waste Registry provided current locations of waste reuse; and a prediction dataset from the Dutch Environmental Assessment Agency provided locations for future supply for construction waste and future demand for construction materials. In chapter 3, a theoretical foundation for understanding locations and scales for closing material loops was constructed by identifying the drivers, barriers, and limitations of circular urban manufacturing - processes that produce goods using local secondary resources. By conducting a literature review and interviewing experts, it was found that there were several caveats to closing material loops at a local scale. Factors that determine the locations of circular urban manufacturers were identified from three perspectives: space, people, and flow. In chapter 4, the factors affecting locations of waste reuse in the Netherlands were identified using spatial correlation. The previously identified space, people, and flow factors were translated into quantitative spatial factors that could affect the location of waste reuse. Correlations were found for flow and space-related factors, but not for people-related factors, which suggests that actors within the waste-to-resource supply chain tend to attract each other and cluster together to form agglomerations, and that locations of waste reuse are not related to attributes of the local population, such as local income, skills, or education. In chapter 5, the location and scale of waste reuse clusters in the Netherlands were then identified using spatial statistical methods. This answered the main research question from a spatial econometric perspective, identifying industrial clusters for closing material loops. It was found that all the studied materials except for glass and textiles formed statistically significant spatial clusters. To determine the scale of spatial clustering, the grid cell sizes for data aggregation were varied, to find the cell size that had the strongest spatial clustering. The best fit cell size is ~7 km for materials associated with construction and agricultural industries, and ~20–25 km for plastic and metals. In chapter 6, to answer the question from a spatial planning perspective, spatial parameters were identified for circular construction hubs - facilities that close material loops by collecting, storing, and redistributing demolition waste as secondary construction materials. Using the Netherlands as a case study, spatial parameters were extracted from two sources: Dutch governmental policy documents, and interviews with companies operating circular hubs. Four types of circular construction hubs were identified: urban mining hubs, industry hubs, local material banks, and craft centers. The spatial requirements for the four hub types were translated into a list of spatial parameters and analysis methods required to identify future locations - site selection, spatial clustering, and facility location. Finally, in chapter 7, spatial optimization was used to identify the optimal scale and location for circular timber hubs in Amsterdam and its surrounding region, answering the main research question from the perspectives of industrial ecology and logistics. The optimal scale was defined as a scale that is most cost effective, minimizing costs and maximizing emissions reductions through timber reuse. The optimal number of hubs for the study area was 29, with an average service radius of 3 km. The cost effectiveness was affected mostly by transportation and storage costs, while emissions savings had minimal effect. As an overall conclusion, five tensions were identified for determining locations and scales for closing material loops, because of the diverse and sometimes misaligned spatial perspectives. The first three tensions are conceptual, addressing contrasting perspectives for defining closing material loops - as urban manufacturing or urban mining; for their locations - as clusters or hubs; and for the factors that affect locations and scales - as spaces, people, or materials. The final two tensions are methodological, addressing contrasting approaches to time - looking at the present or the future; and to methods - quantitative or qualitative.

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The EU has set out to reduce negative impacts from electricity generation on the environment, human health and towards our dependence on fossil fuels. As the fastest growing renewable source of electricity, photovoltaics plays an important role in the energy transition. The manufacturing of photovoltaic modules requires materials classified as critical, making them prone to supply disruptions. Although these materials are essential to the EU economy, they are not sufficiently recovered at the end of a photovoltaic module’s life. An alternative intermediate solution could be to extend the lifespan of existing modules, to slow down demand for these materials in the future.
The aim of this study was to analyse the theoretical options and practical examples of product life extension strategies for photovoltaics. The R-Ladder was used as a guiding framework, which provided examples of life extension strategies. These include Reuse, Repair, Refurbishment, Remanufacture and Repurpose. Aspects for each of these strategies were analysed to find potential benefits and challenges related to four aspects: economics, environment, energy, and materials.
The approach of this study includes a literature review to identify the life extension strategies discussed specifically for photovoltaics in the context of the circular economy. This was followed by a multi-case study on practical applications of Reuse, Repair and Repurposing of photovoltaic modules. Findings from literature and the case study were further supplemented with the insights from six experts. These experts had diverse backgrounds in research, manufacturing, and procurement to offer a variety of insights and perspectives on life extension strategies for photovoltaics. Finally, two scenarios were created for possible life extension pathways for used photovoltaic modules to illustrate the potential impacts compared to a commonplace premature replacement scenario.
Economics and module performance are key factors in decision-making and acquisition of a photovoltaic system. Reuse offers a compelling alternative to current recycling capabilities but offers no sufficient business case. Repair may extend a module’s lifespan to continue the generation of renewable electricity but is only possible in cases of minor damage for which replacement parts are available. Refurbishment could restore more severe damage but is limited by economies of scale and the technical difficulties resulting from current photovoltaic module design. Remanufacturing has the potential to restore a solar cell’s original performance or even upgrade it using newer processing methods but suffers from the same design limitations as Refurbishment. Repurposing used modules can offer a pathway to extract the remaining capacity if it is implemented in a context where generation density is of no concern. Combined, these strategies could buy time to address the resource challenges amplified by the energy transition.

Urban areas are becoming more densely populated. More than 50% of the global population is already located in them. The Netherlands is among the countries with the highest population density. In 2017, 80% of its population was living in urban areas. It is expected that by 2050 the Netherlands will need between 300’000 and 1.6 million new homes. Construction & demolition (C&D) is characterized as a rsource-intensive industry and among the largest consumer of ntural resources. Urban areas account for 80% of global greenhouse gas emissions (GHG) and their infrastructures generate 50% of the total waste produced on earth. Additionally, the increased demand for housing and infrastructure will lead to increased demand for virgin materials and resources, and in turn more waste. From this perspective, the C&D industry will provide a significant contribution to sustainability and will be an important industry for the transition towards a circular economy (CE). The Netherlands has set very ambitious circularity targets for this industry. Specifically, the Government’s Real Estate Agency and Rijkswaterstraat must become fully circular by 2030. Circularity principles address the entire life-cycle of goods and resources, including
waste management practices. The overarching objective is to keep resources within closed loops and at their highest level of utility without losing their technical and economic integrity. As of now, 88% of waste generated yearly by the Dutch C&D industry is currently down-cycled for road backfilling purposes, 1-3% is currently reused or up-cycled for high-value practices and the remaining is incinerated.

The objective of this study is to identify the challenges that are characterizing recovery and reuse practices in the C&D industry in Zuid-Holland and make a preliminary assessment on whether Blockchain (through DLT and Smart contracts technologies) can be a suitable solution for addressing them. The methods
employed for conducting this study blend desk research with qualitative research (in the form of semistructured interviews) and a decision-making framework to assess the use of Blockchain technology.

The results indicate that the materials and construction elements to be considered more interesting concerning reuse and recovery are bricks, steel profiles and window/door frames. The decision-making process driving their reuse and recovery is company-specific and differs significantly across firms. In general, the data required for assessing the feasibility of reuse and recovery for construction elements are the material composition of new and old buildings, supply-and-demand specific information (volume and timing), technical specification and quality-related data as well as market prices. Challenges characterizing reuse and recovery practices are several. First, construction and demolition activities and asset management practices are asynchronous and separated by large time gaps. Material procurement starts significantly earlier than demolition activities and the process needs to be accurate and based on
reliable data. Data management practices are inconsistent and not harmonized among companies. Digital asset management tools (such as BIM), are employed by large companies only and their use on a national scale is neither harmonized nor compulsory. These aspect limit the economic feasibility of reuse and
recovery practices as the accuracy and reliability of data for driving decision-making is poor or nonexisting. Intra-project and intra-firm data sharing are therefore not possible. A Blockchain system which integrates smart contracts and distributed-ledger-technology (DLT) can partly address and tackle these
issues. To address them fully, however, Blockchain technology must be combined with an asset management tool like BIM for making the solution consistent and scalable at an industry level which in turn requires the implementation of national and industry-wide data management protocols and standards that would harmonize the collection, management and distribution of data across the C&D industry. The Netherlands, unlike other EU member states, has, at this point, no government-driven digitalization strategy in place and is rather opting for a market-driven transition.

The Circular Economy (CE) has emerged as an economic paradigm that could provide a pathway to sustainable development. The transition to a CE is a complex process requiring wide multi-level and multi-stakeholder engagement, which can be facilitated by appropriate policy interventions. As value retention processes in the CE require additional labour, the transition from a linear to a circular economy can be viewed as a transition from a capital-based economy to a labour economy. Consequently, a ‘circular tax shift’, based on an introduction of environmental taxation paired with a reduction of labour taxation, could be a powerful lever for public policy.

The aim of this research was to assess the effect of this tax shift on the financial feasibility of circularity in the construction sector. The main research question is: ‘What is the effect of a circular tax shift on the financial feasibility of circular construction, in relation to linear construction?’

To answer this question, a micro-economic analysis has been applied on two circular construction case studies: the ‘The Voice of Urban Nature’ and ‘Circuloco’ pavilions that were built at the Floriade World Expo 2022. A linear and circular variant have been developed for both case studies, for which a life cycle costing analysis has been conducted. A life cycle assessment has been applied to determine the environmental impacts, on the basis of which environmental taxation was applied under the taxation scenarios, which reflected varying levels of the circular tax shift.

The results show that under the current taxation system, the total life cycle costs for the circular variants are 2,0 - 2,7% higher than for the linear variants, though environmental impacts are lower by 38,7 - 52,7%. The effect of the tax shift is that the cost differences between the linear and circular variants decrease, and in two of the high level tax shift scenarios, the circular variant of the Circuloco pavilion becomes more financially feasible than the linear variant. Although the external validity is low, the results of the research imply that the suggested circular tax shift could create incentives to use secondary and biobased materials in construction.

The tax circular shift also implies many other effects, which are outside the scope of this research, but have been suggested as subjects for follow-up research.

Digitalisation pressures the earth's resources, especially critical raw materials (CRMs). The CRMs, are functional materials that meet current challenges and future demands in information and communication technology (ICT). The extraction and processing of CRMs are highly concentrated, mainly outside the European Union (EU). The EU is dependent on import supply. Due to growing demand, an increase in primary CRM mining is expected shortly. Moreover, research showed that primary CRM mining significantly impacts human rights abuse. The increased CRM demand and supply can have an increased effect on human rights challenges. A greater focus is being placed in the EU on preventing and mitigating human rights violations in the global value chain. However, there is limited research in the telecommunication industry on managing human rights in the context of primary CRM supply. The growing demand in CRMs for telecommunication products and technologies highlights the importance of incorporating strategies to secure their business within the telecommunication sector. Therefore, this research aims to answer the following question: What strategies can telecommunication companies deploy in response to human rights challenges in primary critical raw materials supply? The methodology is mainly based on a qualitative approach. The research includes scientific and grey literature reviews, expert interviews, internal documents, and expert workshops. Research data is analysed using the framework on human rights in primary critical raw material supply development.

The research provides an overview of human rights in primary CRM supply. It shows the drivers and barriers for KPN in how to deal with this changing environment. The main focus is on human rights in the context of Conflict Mineral (CM) supply instead of the EU CRM list. Companies don’t have a fixed strategy in place to manage human rights challenges in primary CRM supply. Secondly, a case study is performed on cobalt extraction in the Democratic Republic of Congo (DRC). The general finding was that many human rights challenges occur in primary cobalt mining in the DRC. Various human rights challenges occur in artisanal small-scale mining (ASM) as well as in large-scale mining (LSM). Furthermore, among telecommunication companies, there are different levels of advancement in human rights due diligence practices in CRM supply. However KPN has an emergent strategy on the topic, the company is behind their peers in the level of advancement. At last, a strategy is developed for managing the human rights challenges in primary CRM supply. Experts validated the strategy.

The thesis concludes that becoming a responsible Mineral Initiative (RMI) member and implementing the OECD framework would be a decent start. The RMI provides tools and resources to advance on the topic. Having limited resources and capacity and dealing with complex mineral supply chains makes that a suitable option for KPN. In the medium term, KPN should explore additional actions, which should be the building blocks to advance on the topic and strengthen the company's position.

Further research could focus on exploring case studies CRMs in relation with human rights challenges, and understand the interaction of the system in depth. Moreover, develop schemes and guidelines for responsible supply of all minerals in LSM and ASM sector that are linked to human rights challenges. This is important in order to ensure that companies have a strategy in place. A strategy were human rights challenges are well managed and ensure responsible CRM supply.

Critical Raw Materials (CRMs), materials with high economic importance and supply risk, are the key components of strategic sectors, including Information and Communications Technology (ICT). With foreseeable growth in CRMs demand, principles such as Circular Economy (CE) strategies are gaining attention as means to mitigate risks associated with CRMs. This study examines the effect each CE strategy has on CRMs in servers, via a case study of a Dutch telecommunications company. The study was conducted by collecting industry insights from 16 industry experts and performing a literature review.

Results show that out of 47 types of CRMs, at least 20 CRMs are contained in 4 sub-assemblies and 2 extension tools of a rack server. Among the sub-assemblies, the motherboard is found to contain the most diverse types of CRMs, while the HDD contains the largest amount of CRMs.

CE strategies were investigated in two ways, first by studying current strategies implemented by the company and its value chain partners, and by investigating advanced practices and strategies discussed in the literature. Results indicate that each CE strategy impacts the CRMs in sub-assemblies in different ways, while also having varied limitations in their potential. The result also shows that the current implementation of CE strategies does not always lead to the enhanced circularity of CRMs, as indicated in most of the CRMs being lost in current recycling practices. The degree of effect also differs depending on the strategy and sub-assembly. In the case of the motherboard, substantial potential to improve circularity was identified in the substitution method and advanced recycling strategy, with more CE strategy in need for Ba and P containing components. For HDDs, significant potential was observed in the functional substitution by SSDs and advanced HDD recycling technology. In addition, the strategies’ potential in mitigating the supply risk and environmental impact associated with CRMs was explored. While each strategy is seen to have the potential in reducing risk, its effectiveness depends on multiple factors and further case studies will be necessary to quantify it.

The results imply that enhancing the circularity of CRMs is a complex challenge where diverse interest from actors in the value chain is involved. For this reason, the study stresses the need for active collaboration among value chain partners and system-level support, to be able to design each CE strategy tailored for intended improvement in CRMs circularity. For the advancement of the topic, further studies are recommended, including the four goals of inventing secure ways for CRMs data sharing across the value chain, design for lifetime extension and CRMs recycling via collaboration between suppliers and downstream partners, finding economically viable business models for CRMs circularity, and assessing each CE strategy’s risk mitigation potential via specific case studies.

Businesses are being increasingly pressured to start making the transition from their current polluting economy towards a circular economy (CE) to pursuit a sustainable industry. Indicators for CE play a key role in this transition, enabling the measurement and control of this development. However, the scattered landscape of micro level CE indicators, which varies in purpose and scope, and their ambiguity in measuring environmental and social impact, complicates this transition. Circular consultants are being faced with these challenges when advising the right CE indicator to companies.
This study aims to provide CE consultants the tools to find an indicator that measures CE holistically and that fit their client’s profile. A literature review and interviews with 5 different circular consultants shows that many CE indicators are focused on material efficiency, leaving out aspects that are key for measuring environmental impact such as emissions and pollution. Additionally, social aspects are often not included in CE indicators even though the social dimension of CE is crucial for reaching a sustainable industry. At last, the literature review shows that CE indicators differ in characteristics such as purpose (such as learning or decision-making), their maturity in CE (from beginner to advanced), and data requirements.
Insights from the literature review and from the five interviews with different circular consultants, have led to the development of three tools: a checklist of sub-indicators for CE indicators to analyse their contribution to measuring environmental impact, a checklist of social indicators that are relevant for CE, and a framework to categorize CE indicators on six categories: measurement level, purposes of measuring, company’s maturity in CE, life cycle focus, ease of application and data requirements. The checklist for environmental impact and the categorization framework are applied to five CE indicators chosen from literature. The checklist provides an overview of sub-indicators present and missing in the CE indicators of analysis. Additionally, the sub-indicators in the checklist is translated into a questionnaire for a hypothetical company, to check its practicality. The framework shows that there are notable differences between the five CE indicators: in their purpose, life cycle focus, data requirements and ease of application.
Further work is required to investigate the tension between the CE indicator checklist for environmental impact and the ability of organizations to pick and choose CE indicators – which can be financially driven. Secondly, future case studies could help validate the effectiveness of the indicator checklist for environmental impact and the framework in assisting circular consultants in choosing a suitable and holistic CE indicator for a manufacturing company.

The goal of this thesis is to understand the awareness for and the challenges of the EU conflict minerals regulation. In this thesis the following main question will be answered: How can companies and governance implement the European conflict minerals regulation 2017/821?

The research is focused on investigating regolith as a building material, while implementing the sustainable approach in terms of energy efficiency and material usage, during production process and construction. The context is located within the first manned missions to Mars, and the requirements, towards testing methods allowing for independence from Earth, are implemented.
The studied production process is using compression and thermal treatment as the main processes.The main final product of the research is a novel approach towards the fabrication of martian regolith. The composition of the material is changed in different ways in order to minimize the energy input and required payload for the production process. The compositions with an additional amount of minerals with lower melting point (plagioclase, ferric sulfate), the ones with smaller particle size distribution (amorphous phase elements) or with additional sulfur powder (which could be brought from Earth or extracted in situ in the future) were studied with mechanical tests and microscopic analysis.
The research proved that the change in composition can have a significant impact on the building material characteristics and could be used to optimize the production process. The compressive strength of the produced specimens was ranging between 0,45 – 4,00 MPa.
The structure built in situ was assumed to be external shell structure protecting inflatable, light habitable modules. The outer shell was analysed in terms of resistance towards wind load, gravity and micrometeorites impacts. The construction method and structure type proposed according to the results from experimental research on the material was based on adobe buildings on Earth. The compressive-only structures built with an interlocking system, which protect the crew against wind, radiation and micrometeorites impacts, were studied and designed.

In the context of western linear resource culture, this work represents a socio-technical approach to circularity in the built environment. Object-oriented programming is explored as design method for collaborative domestic environments, in particular to promote circular cooking adapted to local socio-cultural practices.

The Netherlands is vulnerable to supply restrictions because of the importance of materials for economic development: materials are at the basis of the society. The materials that are particularly vulnerable to supply disruptions and are of high importance to the economy are called critical raw materials. The Dutch government has adopted the goal of having an entirely circular economy by 2050 to reduce the vulnerability of the economy to critical materials problems. However, the literature indicates that adopting a new economic model is not sufficient and that a sustainability transformation is essential. According to literature, both a sustainability transformation and economic degrowth are essential to reach a situation of sustainable material use and therefore resilience to supply disruptions. Moreover, the literature emphasises that governance, and especially political leadership, is indispensable in achieving a successful transformation. This research shows how governance can bring about the desired sustainability transformation to reach a social and economic system that is resilient to situations of material constraint in the Netherlands. This study presents a theoretical framework that is tested using the case of governance on material constraint in Britain during the Second World War. The results are applied to the case of the Netherlands to provide insight into the way forward towards a society that is resilient to situations of material constraint.
The results show that a broad approach, including the entire social-ecological system, is essential and that the government can use selective pressures and windows of opportunity to steer and accelerate the transformation. The case study of policy on material constraint in Britain underlines the importance of planning besides the transformation. Additionally, the research has uncovered trust, and therefore the importance of equal and just distribution, as the foundation of resilience.
The Dutch government should take the responsibility of bringing about sustainable development and use its authority to define a sharp vision and specific goals for the sustainability transformation. If diversity and distribution are adequately addressed during the transformation process, the Netherlands is in the position to achieve a high level of resilience to critical materials problems. Resilience does not mean that situations of material constraint will not occur, or that they will not affect the society. It does mean that the Dutch social-ecological system will be flexible enough to change according to the new situation while maintaining its function and provide its society with the basic needs for living, even in times of severe material constraint. The new system is a system that is balanced and diverse, and, therefore, far less dependent on economic growth or material supplies.
Valuable research that could be done to build on this work would be to conduct a similar analysis using one or more different cases, such as the period of resource constraint during the 1970s. Additionally, further research could be done into the different phases of the framework, to provide more insight into specific actions that can be taken to transform a social-ecological system. In a practical sense, this theoretical framework that has been developed in this research can be used by government officials to test its usefulness in helping to develop a transition pathway for the government, including a timeline.

Indonesia is one of the 5 countries in the world that contribute to around 60% of all the ocean plastics in the world. This thesis project is based in the kampungs of Cigondewah, in Bandung, Indonesia. This project tries to deal with the local economies of waste recycling and the informal housing industry. The kampungs are situated next to a major textile factory PT Kahatex that provide jobs to most of the people in the Kampungs. The informal recycling industry also heavily depends on the waste produced from these factories. The idea is to create a decentral circular economy with a collaboration of the building and recycling industry, to develop building materials out of waste plastic. Wastes that are sourced locally can be upcycled into simple and long lasting elements that can provide for affordable and sustainable housing for the low-income population of the kampungs.

The energy transition plays an important role in the building industry. Energy efficient buildings with smart and renewable energy technologies are developments to realize a more sustainable built environment. Photovoltaics, energy efficient lightning and smart grids are examples of these active building components which are broadly implemented to optimize energy efficiency. However, crucial resources for these technologies are critical materials. The European Union outlines critical materials (CRMs) as materials which are highly important for our current economy while the risk of disruption of supply is high. This is not only depending on the limited availability in the earth’s crust, but also on the concentration of their mining areas which causes political interventions. To become less dependent on the import of these materials, more attention must be paid on the current stocks of the EU and an optimized use of critical materials. Hence, a circular use of these materials is required to retrieve the critical materials at the end of the life-time of a product. The extreme small quantities of critical materials within many different applications make them hard to trace. Hence, data on the exact location materials and their next opportunity is required. Data about the stocks and flows of critical materials is considered as highly important to the European Commission and new possibilities need to be developed to link information to datasets of dynamic economic models. These datasets should be standardized to easily compare and combine them.
A positive development in the built environment is the increasing use of Building Information Modelling (BIM). A BIM model makes it easy to collect data of the whole lifecycle of a building and share it amongst all involved stakeholders in the process. This data can be easily exported to other formats for further use.
The aim of this research is to test if BIM is compatible to facilitate knowledge of and solutions for critical materials in the built environment. Firstly, relevant information has been determined on critical materials and circular use of building products containing critical materials, to optimize their lifetime. Subsequently, BIM is tested as an approach to process this information into standardized datasets to make it easily accessible and comparable.
As a case study, a sensor has been analyzed to show a relevant example of the current use and composition of objects containing CRMs. Literature and empirical results shows the difficulty of circular use of critical materials. The extreme small components and amounts of critical material make it difficult and labour intensive to dismantle objects containing CRMs. Thereby the recycling rate of critical materials is low. More efficient use of the materials can be achieved through technical changes in designing for a longer lifetime, new business models and more responsibility for manufacturers and users. Documentation of all required information to lengthen the lifetime of CRMs in BIM appears to be an appropriate solution through the use of IFC files. Herein standardized datasets can be created and exported into many formats for further use. On the basis of specified information in IFC’s, objects in a BIM model can be find searching for instance for ‘critical materials’, ‘Gallium’ or ‘Ga’ and schemes can be exported outlining this information. Concluding a framework is created which provides information on critical materials, material selection processes, optimized used of the materials and finally converts this data into the so called ‘Property Sets’ suitable for IFC. A further challenge is the transparency of the supply chain to receive all the required information. To document all elements, full collaboration and transparency from the beginning of the supply chain is required.

This thesis explores the potential to use factories as sources of water and energy for peri-urban industrian contexts in developing countries. The project is situated in Bandung, Indonesia, on the border wall of a large textile factory surrounded by informal settlements. The project transforms the wall of the factory into a public facility that consists of a public toilet, food market, and factory worker housing. The facility produces energy in the form of biogas, and filters waste water from the toilet for it to be reused by the factory.

Currently the possibilities of sending humans to Mars are being developed. This ambitious and exciting goal demands a broad range of new technologies, innovations and a fresh view on current challenges we are facing on Earth. This also applies to the field of Architectural and Building Technology.

To start with, the need for building a sustainable habitat is established, where sustainability is defined as being as independent as possible from Earth. Therefore, being sustainable on Mars is vital. This aspect is leading to the research by focusing on using in-situ resources (ISRU).

Based on this insight, the research question was formulated: Which in situ materials and forming techniques are suitable to create an outer shell for a sustainable habitat on Mars which protects the crew from the harsh Martian environment? The Martian habitat will have to protect the crew from, among others, radiation and the extreme temperatures (ranging from 20 °C to -153 °C).

Literature study shows that ice provides an excellent shield against radiation. Moreover, ice is widely present on Mars. Hence, a number of experiments were performed to test the feasibility of using ice as a building material. The results for all three tests were the same: the addition of sand or plastic does not upgrade the building properties of the ice. However, adding salt does improve the building properties. The outcome of the experiments indicates that up to 15 ppt of NaCl increases the compressive strength from an average of 1 MPa to 4 MPa. A higher percentage of sodium chloride does not influence the compressive strength. The experiments also indicated that the colder the testing environment (up to -70°C), the higher the compressive strength of the NaCl ice is. The warmer the environment (up to +25°C), the more ductile the NaCl ice behaves.

A further challenge to building a habitat on Mars is that it has to be built semi-remotely. This thesis singles out the use of robotic technology, which can perform all tasks necessary to build the habitat, ranging from mining the ice to assembling the building. A short analysis indicates that the use of additive manufacturing has great potential for the assembling of the building. In this thesis, preliminary studies and experiments have been conducted on additive manufacturing techniques for sodium chloride ice. The main outcome is that the ice structure has a greater overall strength due to the freezing of the ice layer by layer. This technique also enables the possibility of repair during the building phase as the water fills the possible cracks, and then expands upon freezing, creating a stronger structure.

Finally, a habitat has been designed to assess if the technological findings are useful and comply with the overall habitat requirements. The “Ice Hab” uses two different techniques of building with ice; one almost completely independent from Earth materials and another one with Earth technology for redundancy. Overall, the habitat design complies well with the requirements.