This study aimed to define and evaluate the viability of post-use options for excavated concrete sewer pipes. The research was conducted with a combination of literature review and expert interviews with professionals from the Municipality of Rotterdam. The process involved several key steps. The goal was to create a conceptual framework that can evaluate the viability of post-use options for excavated concrete sewer pipes. Initially, the study identified two existing circular economy theories from which four circular strategies were adopted. The potential post-use options for the excavated sewer pipes, were developed based on those strategies such as reuse, repurpose, refurbish, and recycle. The potential post-use options were identified through literature review. Following this, viability criteria were developed from academic literature and expert interviews. These criteria were categorized into general criteria, which must be met by all post-use options, and specific criteria specified to each circular strategy.A conceptual framework was established using the identified viability criteria, designed to evaluate the practical feasibility of post-use options for concrete sewer pipes. This framework was then applied to a test case involving excavated concrete sewer pipes in Rotterdam, serving as a prototype application to test its practical applicability. Seven potential post-use options were evaluated using the framework. From those seven, only two options were considered viable for the test case of Rotterdam. These were, repurposing the pipes for breakwater construction and recycling them using a conservative breaking installation. Other options were rejected due to factors such as insufficient remaining lifetime, lack of structural integrity, and inefficiency. The study concluded by demonstrating the practical application of leading criteria to evaluate post-use options. It also provided insights into the limitations of the study and suggested areas for future research, particularly in improving data accuracy and expanding the applicability of the criteria. However, the study faced some limitations. Some academic criteria were too generalized and not directly applicable to the specific context of concrete sewer pipes. The study heavily relied on expert opinions from the Municipality of Rotterdam, which may introduce bias or limit the perspective to that specific locality

The Dutch Government has raised the offshore wind energy target from 11GW to 21GW by 2030, approximately 50GW by 2040, and approximately 70GW by 2050 (Agency, 2021). The trade-off between achieving sustainable energy sources and extracting raw materials for constructing these infrastructures gives rise to the efforts to transition towards a circular economy. This transition offers solutions to several societal challenges, one of which is resource security (PBL, 2023). Further, academic research emphasizes the necessity of a circular mindset from the beginning of life to achieve a high level of circularity and economic benefits at the end of life (Hall, Topham, & João, 2022; P. D. Jensen, Purnell, & Velenturf, 2020). However, reusing the components and materials of decommissioned wind turbines can act as a driving force for the future requirement of raw materials (Demuytere et al., 2024). In this regard, implementing circular strategies for the existing offshore wind turbines plays a significant role in the energy transition as well as the aim of having a fully circular economy by 2050.

However, circular strategies have limited applicability higher up the R-Ladder in the offshore wind industry due to various technical, economic, regulatory, and environmental challenges. The focus within science and industry has been either on developing circular strategies for the beginning of life or recycling materials to limit future ecological impacts (Hall et al., 2022; P. D. Jensen et al., 2020). The need to address end-of-life resource management for the existing offshore wind turbines is emerging but still needs a systematic approach for sustainable end-of-life decision-making (Delaney et al., 2021; Jadali, Ioannou, & Kolios, 2021; Vielen-Kallio, van Diest, Room, & Knol, 2021; Windemer & Cowell, 2021). Hence, to address the identified gap, the research developed a comprehensive circular decision-making framework that leverages a standardized data management system, specifically a Digital Product Passport. To achieve this research objective, the main research question is framed as follows:

“In what ways can a decision-making framework for a standardized data management system,
specifically tailored for the end-of-life phase of OWTs, contribute to enhancing circular practices by efficient resource management within the industry?”

Sustainability is increasingly important for homebuyers due to environmental awareness, legislation, and financial benefits like reduced energy costs and higher mortgage potential for energy-efficient properties. However, evaluating a home's sustainability is challenging as properties may be misrepresented by the seller. Further on, the bounded rationality of homebuyers can also affect property assessment. This thesis explores the legal obligations applicable to homebuyers in assessing sustainability before purchase, explores current market practices for assessing sustainability, and explores professional property evaluation. Thereby, this thesis aims to use insights retrieved from professional investors to guide homebuyers in making informed decisions on sustainability when buying a residence.

A mixed-methods approach, including a legal review, interviews with professional investors, and a survey among homeowners, was used. The legal review indicates that buyers must conduct thorough property investigations. Energy labels provide information but do not guarantee specific features and should be compared with the true state of the property and seller information. Annulment of a purchase based solely on an energy label is difficult without false disclosures.

Interviews reveal that unsustainable properties are losing value, partly due to legislation limiting the lease of such assets to tenants. Professional investors use various methods to assess sustainability, such as comparing assets with reference objects, seeking external advisory, assessing development potential, examining energy consumption data, evaluating climate risks, understanding energy labels, considering certifications like BREEAM, assessing embodied carbon, and evaluating asset installations and insulation.

The survey shows that sustainability is increasingly important to homeowners, primarily to reduce energy costs. Respondents are willing to pay more for higher energy labels but often fail to thoroughly investigate property sustainability, highlighting this study's relevance. Greenwashing was not a significant issue among respondents.

This study supports previous research on the importance of sustainability and the need for thorough property investigations. Limitations include the difficulty of generalizing legal rulings, the small survey sample, and potential interviewer bias. Evolving legislation, fluctuating energy prices, and the volatile housing market may quickly render results outdated.

Homebuyers are advised to consider the energy label, check its assessment date, and conduct additional research before purchasing. Homebuyers are advised to request previous energy consumption data and consider risks related to heat, flooding, and foundation damage. External advice is recommended, especially for homes built before the 2012 Building Decree. The state of installations can be assessed with further external certification. While solar panels can improve an energy label, proper insulation is more crucial. Limiting energy demand should be prioritized before focusing on green energy generation.

It is well known that construction is one of the most polluting sectors worldwide. The nitrogen crisis has led to the suspension of numerous projects on multiple occasions in the past. We are also increasingly faced with scarcity of materials and the effects of climate change. Therefore, it is time for change, a transition towards more sustainability in construction. This thesis specifically researched the offshore energy sector where the Dutch and German Transmission System Operator (TSO) is enabling the transition to a more sustainable future by employing partnerships.

This thesis contributes to the current debate on partnerships by researching how a partnership in the offshore energy sector should be set up to enable achieving sustainable objectives. First, a literature review is conducted followed by an empirical research using a single case study originating from the Dutch and German TSO TenneT called the 2GW program. Semi-structured interviews were conducted and followed by a thematic analysis. For the discussion, a form of discourse analysis was deployed, specifically the dialectical-relational approach.

The results indicate that the successful launch of partnerships to enable achieving sustainability goals within the offshore energy sector is currently hampered by several obstacles. The discourse analysis revealed three main obstacles: fear of the unknown, limited market competition, and challenges in implementing the partnership approach.

The conclusion offers a comprehensive roadmap that can be utilised by similar public clients in the offshore energy sector and with some adjustment in other sectors as well (where consideration of environmental factors is essential). The research recommends fostering market incentives to increase competition, promoting clear communication and education about sustainability goals, and encouraging a cultural shift within organisations to embed sustainability into their core values.

The rapid urbanization of cities has led to densely constructed environments that create significant challenges for municipalities in integrating urban greenery. The absence of urban greenery negatively impacts climate-related issues such as increased temperatures, poor air quality, and biodiversity loss, while also diminishing residents' quality of life. As urban greenery is essential for healthier and more sustainable cities, this thesis addresses the complex decision-making processes municipalities face in implementing urban greenery, focusing on small projects in densely developed urban areas. This leads to the following research question: “How can municipalities effectively overcome the challenges encountered in the decision-making process for implementing urban greenery?”

A qualitative research approach was conducted, consisting of a systematic literature review and semi-structured interviews. The literature review analyzed articles to identify theoretical barriers and enablers, while the interviews with employees from five Dutch cities (Amsterdam, Rotterdam, The Hague, Utrecht, and Eindhoven) provided practical insights into the real-world challenges municipalities encounter. A thematic analysis categorized 182 barriers into 36 types and 110 enablers into 44 types.

The key barriers identified in this research are ‘Fragmentation in coordination and responsibilities’, ‘Lack of funding’, and ‘Limited space allocation.’ The most identified enablers are ‘Community engagement’, ‘Raising awareness’, and ‘Car restraint policies.’ Findings indicate that the high interconnectedness among barriers and enablers complicates the development of clear mitigation strategies, emphasizing the need for municipalities to adopt flexible, context-specific approaches. The interconnectedness also makes it challenging for municipalities to decide where to start. To address this, the identification framework for barriers and enablers provides a structured approach that enhances awareness and guides more effective decision-making.

Key recommendations for future research include assessing the relevance of the findings in smaller or non-European cities, exploring urban greenery on private land through partnerships, and incorporating diverse stakeholder perspectives beyond municipal employees. Additionally, future studies could focus on strategies to address the barrier ‘Fragmentation in coordination and responsibilities’ or validate the effectiveness of the proposed identification framework.

In conclusion, municipalities face unique and complex challenges in urban greenery implementation, and there is no general solution. Tailored strategies, enhanced collaboration, increased awareness, and the use of an identification framework for barriers and enablers can help municipalities to implement successful and sustainable urban greenery projects, contributing to climate resilience and improving the quality of life in urban areas.

The Dutch infrastructure sector faces significant challenges in investment decisions
under uncertainty, particularly in large-scale projects with long lifespans and high sunk costs.
Traditional methods like Cost-Benefit Analysis (CBA) often fail to account for the value of
flexibility and strategic options, such as deferring, expanding, or abandoning projects in
response to changing conditions. This research examines the Real Options Approach (ROA) as
a complementary method to enhance decision-making in this context. Originating from
financial economics, ROA provides a framework for valuing and managing strategic
investments by recognizing the intrinsic value of flexibility in uncertain environments. The
study assesses the current use of ROA in the Dutch infrastructure sector, identifying barriers to
its adoption and potential enablers. Through literature review and empirical research, including
interviews with key stakeholders, the research highlights the practical challenges and
opportunities associated with implementing ROA. Findings suggest that while ROA is
theoretically appealing, its practical application in the Netherlands is limited due to entrenched
standardized decision-making processes and the significant influence of political
considerations that often prioritize short-term gains. Additionally, there is a widespread lack of
familiarity with ROA, and it is perceived as complex, requiring substantial time and financial
resources. To enhance ROA adoption, the research recommends effective communication to
raise awareness of its benefits, targeted training to build stakeholder competence, and the
simplification and standardization of ROA processes with clear documentation. Moreover,
fostering a cultural and organizational shift towards flexibility and adaptability, along with the
gradual integration of ROA into decision-making, is essential. These measures are crucial for
bridging the gap between ROA's theoretical potential and its practical application, leading to
more informed, flexible, and resilient investment decisions under uncertainty.

This thesis explores the factors that influence sustainable decision-making among construction contractors in Albania. The country has been a candidate for membership of the EU since 2014, and the construction sector is a pivotal part of the economy. However, it is also one of the industries that contributes the most to environmental degradation. This intensifies the urgency of adopting sustainable practices. Nevertheless, the construction sector faces several challenges to sustainable development, including limited access to sustainable materials, the lack of control by government, and financial constraints. Using a mixed-methods approach, this research combines a literature review, semi-structured interviews, and questionnaires conducted among Albanian contractors to identify the key determinants of sustainable decision-making. Results revealed that the main factors that influence contractors' decisions were cost, government regulation, material availability, client preferences, and the contractors' experiences. The lack of robust policies was identified as a major barrier, highlighting the necessity for government to establish regulatory frameworks to support sustainability. The conclusion recommends that Albanian policymakers should implement stricter sustainability regulations, allow greater availability of sustainable materials, and increase training and awareness programs for contractors following a EU standard.

Public clients in the Netherlands have committed to dramatically reduce CO2 emissions. To achieve that, Circular Economy is proposed and more specifically a tool that can lead to Circularity, called Product Service Systems (PSS). PSS is a business tool that is innovative for infrastructure, and public clients are investigating the transition towards service-oriented projects. Literature suggests that when public actors undergo transitions, their public values are also affected. It is yet not thoroughly studied how the public values are coupled with PSS. Aim of this research is to investigate how public values are affected when public actors that own infrastructure assets implement PSS. Firstly, a literature review concerning public values is conducting. Then, the PSS characteristics, barriers and benefits are theoretically studied. A framework that couples public values with PSS is designed. To analyze and enrich this framework, a real-life implementation is studied. The Province of North Holland (PNH) served as case study, and more specifically the guardrails pilot that PNH realized within the Circular Road Program. Interviews were conducted to collect the data. To analyse the interviews, thematic analysis was utilized. Two rounds of analysis were conducted, a deductive and a reflective round. The findings of the thematic analysis were validated and generalized by an expert panel consisting of three experts. As a result, the empirical findings of the results were found. An overview is designed and the theoretical and empirical results are presented and compared. The values that are mostly affected when PSS is implemented are Lawfulness, Accountability, Collaboration and Innovation. The overview is a useful input for public clients, because they can gain knowledge about how they can include the values perspective in their decision-making process.

Issue:The issue addressed in this research is that due to the transition from a linear to a circular real estate construction sector, the position of demolition contractors in the stakeholder network will change. This will change the relations of demolition contractors with other stakeholders. Research is required on how stakeholders in the circular real estate construction sector can engage with demolition contractors.

The global shift toward a circular economy, vital for tackling climate change and resource security, necessitates the integration of circular principles in the construction sector. Urban planning, significant in shaping the built environment, offers an opportunity for implementing these principles comprehensively. However, limited implementation in area development projects is observed due to ambiguity in design themes, timing of strategy definition, and lack of coordination in urban planning. This research addresses these gaps, focusing on integrating circularity in different urban area development phases. The methodology employed a qualitative case-based design study involving a literature review and comparative case study. It identified eleven crucial circular design themes through a systematic literature review. Furthermore barriers, accelerators, and lock-in moments in area development processes were identified through the comparative case stud. These findings have been combined, resulting in the development of eleven phase-wise guidelines for circular area development processes. These guidelines, validated through stakeholder input, encompass change management elements and recommendations for overcoming barriers, thereby optimizing the incorporation of circular design strategies. The guidelines, usable in all process stages, strike a balance between clarity and flexibility, enhancing stakeholder engagement and decision-making. However, further research is recommended to generalize findings, explore the practical application of evaluation sessions, and address technological barriers hindering the transition to a circular economy.

The application of vertical greening systems (VGS) onto building envelopes constitutes an innovative way to implement more green in the living environment. Especially in dense urban areas, where only limited space is available to integrate more horizontal greening at ground level, VGS have the potential to contribute towards creating a greener, healthier, more nature-inclusive and climate resilient urban environment. This by facilitating and contributing to natural ecosystem functioning, hence providing ecosystem services and through those, benefits for society. These benefits include among others an enhanced microclimate, biodiversity and aesthetic appeal, as well as improved physical and mental health, thermal performance, energy efficiency and air quality, and reduction of urban heat island effect and noise disturbance.

In order to substantiate the total set of costs and benefits associated with VGS implementation and enhance rational decision-making, in present research the development of a standardised framework and interactive economic valuation tool is proposed.

In the end, an economic valuation framework and tool were developed which can support the decision-making process regarding VGS application. The framework is based on Life Cycle Cost Analysis (LCCA) and Social Cost Benefit Analysis (SCBA). These analyses relate to real estate investors and society (resident focus) respectively. To assess and report on the values of the costs and benefits of these innovative systems, distinct themes were established. The cost themes entail financial costs, environmental costs and potential Ecosystem Disservices. Benefits are distributed over the themes health & well-being, climate adaptation & mitigation, real estate, social & recreational & commercial and biodiversity.

The current version of the tool is able to perform quantification and monetisation for financial costs, large parts of the environmental costs, reduction of airborne PM10, increased rental incomes (investors) and rental costs (residents), reduced energy usage for heating and MIA & Vamil tax incentives. Based on implemented valuation methods, the case study delivers project specific results. Though, it is explicitly noted that these results do not yet provide a complete representation of all costs and benefits, due to a limited number of (benefit) indicators that are monetised. Hence, this version of the tool should be regarded as initial impetus for further development. This in order to ultimately obtain an all-encompassing VGS Valuation Tool, fit for project specific economic valuation of costs and benefits of VGS.
The result dashboard visualises the valuation outcomes and results in clear tables and graphs, generating insights into the contribution of different themes towards the total costs and benefits of VGS. This can initiate further recommendations for a research agenda into distinct aspects of certain VGS.

Hence, the VGS Valuation tool could become a conversational mechanism or steering instrument, to stimulate or justify choices for specific types of VGS at given locations. The test panel of anticipated end users was enthusiastic about the comprehensiveness and user experience of the tool and acknowledged its future practical value.

The Paris Agreement was created in an effort to enhance the global response to the issue of climate change. To reach this goal, greenhouse gas emissions must be at least 40% below 1990 levels by 2030 and the temperature rise must be kept below 2 degrees Celsius this century. Moreover, the recent fossil fuel price increases, are pressing eye-openers to the geopolitical dependency on a small number of nations and mark the urgency of the energy transition.

Hydrogen generation as a means of energy distribution and storage is argued to be a viable solution to this challenge because this flexible energy carrier can be produced by any energy source and can be converted into various energy forms. The energy carrier is believed to be critical for decarbonising heavy industries, heating, and transportation.

Although hydrogen can be produced from a variety of energy sources, the only long-term key to facilitating the energy transition and establishing a new green economy would be through the electrolysis of water, fueled by renewable energy. To be economically viable, the energy would have to be provided at a large scale and at a competitive price. This makes it a global endeavour, requiring cross-border collaboration to create international supply chains.

With its potential to generate an abundance of wind energy, geothermal energy, and hydropower, Iceland is exploring its opportunity to produce hydrogen for its domestic markets and export markets. Therefore, this research is taking the Icelandic situation as a case study.

A lack of infrastructure to create, store, and transport hydrogen in significant amounts is one of the obstacles to developing the hydrogen economy. Infrastructure development needs effective coordination and substantial expenditures. In this sense, port authorities play a crucial role in bringing together all the relevant parties in the supply chain. However, creating a long-term plan to convince investors and other decision-makers presents a hurdle. The creation of a port master plan is constrained by numerous uncertainties, limited technological knowledge, and unknown social needs. There is a need for strategically roadmapping the port development process and thus structuring the decision-making process. So far, no hydrogen industrial port complex has been built and no studies have been performed about systematic thinking for the purpose of generating the possible pathways to develop such a system.

Through a single-case and practice-oriented design research methods, this research performs a SWOT analysis to determine influencing factors in developing a hydrogen industrial port complex in Iceland. This leads to the creation of an eight-phase Integrated Hydrogen Port Development-framework to narrow the knowledge gap as described above. Ultimately, this research also describes a narrative that describes practical recommendations for the Fjarðabyggð port master plan.

The airline industry is going through a big transformation. The institutional environment as well as the industry itself has changed. Competition with the entry of the low-cost carriers in a market that used to be dominated by flagship carriers and societal pressure regarding sustainability on airlines with COVID-19 state aids increased, while the shortage in the labour market limited the pace of recovery. The technologies that airlines use to operate have been outdated to cope with today's massive challenges. All of these changes forced airlines to innovate to maintain their services. During the era of technology, these innovations can be better nurtured within an innovation-conducive environment, which might be seen as an ecosystem designed for the co-creation of value through collaboration. In the last decade, both managers and scholars showed an increasing interest in the concept of innovation ecosystems, which provides a holistic perspective for value creation. However, despite its potential, the implementation of the innovation ecosystems in the airline industry and how it can support an airline to implement its innovation strategy has not been investigated. By conducting literature research and qualitative embedded case study, this research concludes that implementation of innovation ecosystems and innovation ecosystem strategies can help an airline to achieve its objectives on innovation and implement its innovation strategy by aligning its innovation processes, overcoming the barriers to innovation that hampers its innovation processes and finally facilitating the collaboration within and beyond the value chain to develop radical innovations that are required to cope with today’s complex challenges.

Rijkswaterstaat has introduced the two-stage model in the Dutch construction industry in order to reduce risks in large and complex projects (Rijkswaterstaat, 2020a). However, it is also possible that the two-stage model can influence the sustainability of infrastructure projects since the risks are reduced and a different way of collaboration between market parties and public parties is introduced. Nevertheless, it is unknown if the two-stage model makes an impact on sustainability of infrastructure projects. Boskalis Nederland, where this research is performed, is interested in if the two-stage model can make an impact on sustainability of infrastructure projects because of the high relevance of these two topics in the Dutch infrastructure sector. Therefore, the main objective of this study is to explore the impact of the two-stage model on sustainability of infrastructure projects. Taking into account the knowledge gap, the problem statement and the research objective, the main research question is defined as follows: "What is the impact of the two-stage model on sustainability of Dutch infrastructure projects?".

The expectation regarding the impact of the two-stage model on sustainability of infrastructure projects is that the model will offer market parties and public parties more room to discuss, incentivise and implement sustainable solutions in infrastructure projects because of the integral collaboration between the parties in the project team. The impact of the two-stage model on sustainability could be seen when comparing the model to a one-stage collaboration model. For example, a technical specification (which is a one-stage collaboration model), is characterized by having result-oriented specifications prescribed by the public client which results in leaving little freedom for the contractor for sustainable input in infrastructure projects. In contrast, the two-stage model is characterized by collaboration between the involved parties which creates more freedom for input on sustainability from the involved parties. This may lead to a bigger chance to implement sustainable solutions in infrastructure projects. The essential difference between the two collaboration models is the collaboration aspect between the involved parties, which eventually may make a difference in chances to implement sustainable solutions in infrastructure projects.

In the past decades, sustainability has become increasingly important for the construction industry, in particular highway infrastructure, as it can generate both positive and negative impacts on the social and physical environment. As a result of the impact on the environment and the growing awareness of environmental protection, the effects on society and economic development, there is a pressing need and sense of urgency for the sector to become more sustainable. For a highway to be truly sustainable it needs to take the social, environmental and economic dimensions of sustainability (People, Planet, Prosperity) into account. Over the past decades, some sustainability assessment (SA) approaches have been developed in an attempt to integrate sustainability in the assessment of infrastructure projects. Despite these attempts, these SA approaches do not address all the dimensions of sustainability thoroughly and are biased to either an environmental or an economic assessment, while the social dimension is taken less into consideration. However, how designers and decision-makers can integrate these dimensions into the assessments of highway design options is less known. This lack of integration of the three dimensions of sustainability makes it impossible to evaluate and assess the sustainability consequences of highway design choices and options and thus represents a significant limitation.

To address the observed problem, the main objective of this research is to not only provide designers and decision-makers with a SA tool that integrates all three dimensions of sustainability, but also with an understanding of how this can be used.

The triple bottom line (TBL) theory coined by John Elkington, a well-known concept in sustainable development (SD) was selected as a sound theory regarding the three interdependent dimensions of sustainability. A total of 64 SA criteria from the construction and infrastructure sector were identified through surveying recent literature, which formed the preliminary list of SA criteria. This was followed by a filtering process on the SA criteria and subsequently a questionnaire survey to establish which are relevant to the Dutch highway context. This resulted in the conceptual SA framework which consists of 36 SA criteria categorised in their corresponding dimensions of sustainability and related 9 themes. Next, the assessment procedure was provided for the conceptual SA framework, to form the proposed SA tool. In this tool, the best-worst method (BWM) is used to determine the weighting factors of the themes depending on the project. The tool was tested by applying it to a reference case (a highway project in the Netherlands). Based on the results from the reference case, the applicability of the tool was evaluated by an expert involved in the project. In the developed SA tool, the three dimensions of sustainability are integrated into one comprehensive framework specific for the Dutch highway context.

The conceptual SA framework provides a systematic overview of all possible aspects of sustainability that can be taken into account during the planning- and design phase of a highway project. In addition, it can help designers and decision-makers understand how the dimensions of sustainability can be used to decrease the negative impacts of highway projects and embrace the principles of sustainability with respect to environmental protection, economic profitability and human well-being, to make their highway designs more sustainable and to contribute towards SD.

The proposed SA tool can assess, compare, evaluate and rank design options based on the SA criteria. The SA criteria assess to what extent a design choice and option contributes to the creation of sustainable added value. In this tool, design options can be explicitly weighed upon all dimensions of sustainability, related themes and corresponding SA criteria which can support the decision-making.

The number of raw materials consumed and waste generated by the construction industry is no longer a viable solution in the future. It is required for the construction industry to move from a linear towards a circular economy (CE) by circular construction (CC). The unfamiliarity in actions that need to be taken for CC is still new terrain for many companies since the whole life cycle of a project needs to be considered and is plagued with technical, legal and cost issues that obstruct CC.
Contract forms such as Early Contractor Involvement (ECI) involve contractors in the design phase of a project, such as suppliers, builders, and demolition contractors, to engender a better design by sharing and creating new knowledge. There are, however, no sources directly indicating that the benefits of ECI also regard circularity. At the same time, issues that emerge with CC remain an obstacle for fully transitioning to a CE.

This research aims to understand better the issues regarding CC and if ECI would be beneficial in solving them due to the knowledge contribution of contractors and their collaboration with other parties in the design process. Therefore the research question is framed as follows: “How is contractor’s knowledge contribution improving circular construction in ECI context?”

The research consists of a literature study and an empirical study. First, the literature study was conducted to define the relevant concepts such as ECI, CC and knowledge processes. Next, to understand the knowledge contribution of contractors to CC in the design process, interviews with practitioners involved in CC projects were conducted according to the Critical Incident Technique (CIT). In CIT, research participants are asked to recall and describe a time when a behaviour, action, or occurrence impacted a specified outcome positively or negatively.

From the empirical study, there can be concluded that contractors' knowledge contribution plays an essential role in the feasibility of a circular design solution. However, the dynamics in collaboration between multiple parties can lead to better circular results. Since the collaboration can result in knowledge creation and sharing, developing a good work relationship between contractor and client and problems can be jointly solved when there is mutual support. This, however, also requires trust and transparency between the parties, and if lacking, it can obstruct CC.

Smart City has become one of the most popular topics in recent years due to the emergence of innovative digital technologies. Start-ups have been active in an innovation system defined as Smart City Entrepreneurial Ecosystem (SCEE) in this study, where stakeholders in the Smart City industry are involved and interact with each other, including start-ups, government, industry players, knowledge institutions, citizens, etc. It is observed that start-ups have encountered the “valley of death” problem in their early development stage with limited commercial resources such as funding, unstable customers, brandings, etc. Hence, it is imperative to research the SCEE and figure out how to help start-ups address these problems by strengthening favourable interactions with other actors in the ecosystem. Since little research has been done on the development and analysis of SCEE, this study aims to develop a theoretical framework of SCEE with the systematic literature review and apply it to analyse the case of Brainport Smart District (BSD) by using Social Network Analysis. The developed theoretical framework consists of sixteen groups of actors under four main categories (i.e., government, academia, industry, and society) and ten types of interactions. As for the social network results, the social network of SCEE is relatively condensed; its diameter is 3, the average clustering coefficient is 0.622, and the average path length is 1.697. Start-ups/SMEs, the local management team of BSD, users & consumers, and software & hardware infrastructure providers are the key players with high values in terms of degree centrality, betweenness centrality, closeness centrality, and eigenvector centrality. When it comes to interactions, most interactions happened between start-ups and actors in the government and industry. And there is also a self-loop in the social network of the SCEE in BSD, which means that start-ups are interacting with other start-ups in the ecosystem. Identifying key actors will be helpful for policymakers or other actors to make strategic decisions to improve the SCEE and create a better environment for start-ups to thrive and grow. The analysis of interactions provides guidance on how to improve the current interactions between start-ups and other actors and points out what interactions are lacking in the ecosystem. This study not only fills in the knowledge gap in the development and analysis of SCEE and benefits scholars interested in this field but also can be adopted by policymakers and practitioners to improve the whole ecosystem and stimulate entrepreneurship and innovation in smart cities.

The circular economy in the construction sector aims to lessen the environmental impact of construction projects by incorporating the end-of-life phase into the design and the conscious use of reusable resources. To achieve a circular economy in the built environment, it has been evidenced in the literature and practice that governance mechanisms in inter-organizational collaboration are required between the multiple parties involved to quickly rethink the purpose of the project, the desired outcome, and the aligned efforts towards the solutions of circular challenges. This research gains insight into the governance mechanisms that have proven to be desirable or beneficial in the collaboration between public clients and main contractors during the front-end phase in building projects with circular values. It is accomplished through two stages: (1) a comprehensive literature review was conducted where 25 articles were selected based on keywords related to inter-organizational collaboration. It brought the most representative knowledge of the existing forms and types of collaboration on construction projects, as well as an existing framework created to analyze the approaches for coordination, adaptation, and safeguarding of exchanges between the focal parties of inter-organizational projects. The literature included a second search of current circular practices in construction projects; (2) a multiple-case study strategy was conducted to explore how the inter-organizational collaboration between public clients and contractors was governed toward the delivery of circular building projects. Data was collected from publicly available documents and semi-structured interviews on the three cases that shared the most similar approach based on applied circular practices. This study's result contributes to the current literature and practice by asserting that governance mechanisms in inter-organizational collaboration between public clients and main contractors facilitate the adoption and implementation of circular practices in building projects. The results expressed that relational and contractual governance mechanisms complement one another in goal-setting, capability building, roles and decision-making, rewarding, coordination, and monitoring. Various governance mechanisms within each of these dimensions can be employed to pursue circular practices under specific contexts, thereby supporting the transition to a circular economy in building projects.

The aim of the thesis investigates and addresses what strategies municipalities can use in relation to collaborative action in a collaborative governance setting to facilitate heat transition at regional scale. The heat transition is a multifaceted problem where fragmentation and a deficient direction role of municipalities is a key institutional challenge. To address the problem, regional energy strategies are established to collaborate with state and non-state stakeholders, but the heat transition is still stagnating today. Collaborative governance is a governing arrangement that engages public and non-public organizations in a collective decision-making process to implement public policy to resolve social-technical problems. However, today the application of the collaborative governance theory is scarce on sustainable transformation. For this reason, the author decided to apply a collaborative governance lense on the current situation for heat transition.

The thesis first examines the collaborative governance framework, which is the most suitable to apply in relation to heat transition. In the second step, the selection of a comparative empirical research methodology is selected. Third, two RES regions with rural characteristics are investigated to get insight into the current situation. Lastly, the empirical findings are discussed in relation to current collaborative governance literature and governmental policy. Finally, recommendations for municipalities and other regional stakeholders can be provided.

The empirical findings show that collaborative governance conditions are rarely present to facilitate the heat transition at regional scale. The author identified crucial conditions within the system context and collaborative governance process itself, which is explainable by the iterative nature of the model. The conditions include the current deficient policy and legal framework, high level of contention among citizens, inadequate resource conditions. In the collaborative governance regime itself this results in lack of interdependence, trust and high level of uncertainty, through which no shared interest or common language are practiced. The thesis concludes with recommendations for the regional collaboration regarding heat transition for practitioners and for future research on collaborative governance.

The construction sector, as one of the world's greatest waste generators, is responsible for a cascade of events such as global warming, climate change, and natural resource depletion. Raw materials are continuously extracted from nature, and the rate at which they can refill is insufficient to meet demand. This system suffers significant losses across the value chain (Ellen MacArthur Foundation, 2013). On the contrary, the circular economy concept proposes a circular model of 'reuse-refurbish-recycle' that focuses on reducing waste and optimizing resource value retention. The strategy is ideal to adopt in a high-growth, high-waste sector like the built environment. The reason this research was taken up is because a significant gap is seen within valuation practices. The current valuation methods, although efficient, collect data and provide property valuations based on previous studies. For example, when using a comparative method of property valuation, we compare one asset with a neighboring one, that has similar features. This process incorporates the older values already provided to this old building, without accounting for innovations such as reusability or adaptability of the components How different would the sector be if we incorporated the value of circular interventions to the original value determined, rather than looking back at older valuation standards? Will there be a significant difference, and, more importantly, would it impact the way real estate investors viewed circularity? On conducting the research, The primary hypothesis of this study was that there is a link between circularity and valuation and that this link can be incorporated within present valuation procedures. The thesis research explains how the connections can be made, as well as specific actual instances for each. The number of possible scenarios are endless.