In the Netherlands, the built environment is responsible for half of all raw material consumption and contributes 40% of the total country’s waste production. This characterizes the current prevalent unsustainable take-make-dispose process. To address the significant impact, a transition to a circular economy that prioritizes materials and circulates resources is essential, operationalized through the application of circular strategies. Adaptive reuse projects oUer significant potential to support this transition by extending the lifespan of existing buildings. However, existing literature highlights several barriers that hinder the eUective integration of circular strategies in adaptive reuse projects. This includes fragmented collaboration and the absence of structured guidance on organizing the development process. While strong collaboration across the development process is recognized as a key enabler, there is little insight into how it should be organized. This lack of guidance is especially critical in the early development phases, where key decisions are made that shape the project’s potential for circular outcomes. Moreover, the developer’s important role in facilitating collaboration is often approached from a general perspective, without a specific focus on their viewpoint or position. To address this, this research aims to answer the following research question: ‘How can Dutch real estate developers organise the early phases of the development process to support the integration of circular strategies in adaptive reuse projects?’ To arrive at an answer, this research combines theoretical research with qualitative empirical research. A multiple case study is conducted, drawing on interviews and document analysis to provide in-depth insights. A focus group with real estate developers was undertaken to validate cross-case findings and to explore explanations for results not fully captured by theory or cases. The study identifies the distinct role of each early development phase, inception, feasibility, and design, in supporting circular outcomes. It also outlines key circular strategies, actor roles, and phase-specific activities that enable integration of circular strategies in adaptive reuse projects. The findings emphasize that the early development phases do not follow a strictly sequential order. Instead, feasibility and design often progress iteratively, shaped by project-specific conditions and evolving circular ambitions. Furthermore, the study reveals that a developer can play a proactive role by aligning actors with circular ambitions. These insights are synthesized into a normative framework, providing phase-specific guidance for real estate developers in organising the early phases of adaptive reuse projects to support the integration of circular strategies.

Regeneration in the built environment is characterized by going beyond the goal of minimizing environmental harm to become net-zero – or in other words 100% sustainable. It emphasizes the need to create net-positive impacts for the social-ecological system through the process of creating the built environment. The aim of this master thesis is therefore to clearly define regenerative development and regenerative design, as well as to explore which regenerative principles exist and how they can be practically applied throughout a project’s life cycle. The research methodology is a mixed-methods approach, consisting of an extensive literature review and three Dutch case studies of real estate projects. The four research outcomes are: (1) a clear definition of the key terms in the regenerative built environment context, (2) a review and summary of the regenerative principles stated in the existing literature, (3) a framework or guide for the application, assessment and implementation of regenerative principles in practice, and (4) an evaluation of projects in the built environment from a regenerative perspective. The research concludes that the selected projects have regenerative aspects, but realizing fully regenerative projects also requires a mindset shift.

The construction sector has a substantial impact on climate change. In the Netherlands, the
construction sector accounts for nearly 35% of the Netherlands’ CO₂ emissions and half of its
resource use. Although Dutch recycling rates are relatively high, the use of secondary materials in new construction is still very low. Given the national ambition to achieve a fully circular economy by 2050, this represents a missed opportunity. Within buildings, structural components account for the largest share of embodied carbon and should therefore be targeted for reuse. Collaboration among key actors in the construction value chain, including actors such as developers, architects, contractors, advisors, and demolition companies, can enable this reuse, but research is limited on this topic.

This research explored how collaboration among the mentioned actors could enable the reuse of structural components from buildings reaching the end of their lifecycle. A qualitative approach was used, incorporating semi-systematic literature reviews, case studies, semi-structured interviews, and workshops. First, the study identified factors that affect the reusability structural components. After this, the study identified barriers and drivers in the reuse process, as well as the collaborative process needed such as roles, knowledge, and workflows. This was followed by a workshop that incorporated these results and identified different strategies for collaboration.

It is found that the key barriers to structural reuse are primarily economic, organizational, and
social, rather than technical. Fragmented information, misaligned timelines, and unclear roles
often hinder the practical implementation of structural component reuse. The resulting strategy guide addresses these barriers and proposes actionable strategies for the early project phase. The guide offers collaborative strategies that embed reuse into the routines, roles, and dynamics of construction projects.

This study explores how rooftop extension projects can be evaluated more systematically, paying specific attention to their strategic, technical, financial, and societal implications within portfolio-based investment decisions. In a context of mounting housing shortages and spatial constraints in Dutch cities, innovative densification strategies are becoming increasingly important. Rooftop extensions, adding extra layers to existing buildings, are often regarded as promising because they add dwellings without additional land take and align with circular ambitions. In practice, however, housing associations still treat such projects largely as incidental initiatives, assessed with generic tools originally designed for new-build or large-scale renovation. The research combines a literature review on adaptive reuse and investment structures with five case studies. For each case, two interviews were conducted, one at a strategic level and one at an operational level, and the conceptual assessment framework was validated by an expert panel. The findings show that decision making on better use of the existing stock is evolving in some associations. Risk perceptions, such as technical uncertainties, planning constraints, or construction in occupied buildings, are examples of identified barriers. At the same time, the cases illustrate that rooftop extensions can support integrated renovation, enhance neighborhood livability, and increase typological diversity.
To help housing associations assess these projects more systematically and enables to argue investment decisions more robustly, an evaluation framework was developed with three components:
• Knock-out criteria, such as critical project mass;
• Opportunity valuation, for aspects such as circularity and housing differentiation;
• Key considerations relating to risks and policy alignment.
The study concludes that further professionalization is needed to embed rooftop extensions firmly within development and investment strategies. This requires explicit integration into portfolio policies, greater attention to societal value, early coordination with municipalities, and ongoing internal knowledge development. Standardizing design and permitting procedures can facilitate wider applicability and scaling.

As construction projects become more complex, the amount of information is expanding. Contractors have adopted Systems Engineering (SE) to effectively capture this information of a system and ensure complex projects are realised on time and meet the high-quality needs of clients. However, the traditional use of documents and dispersion of information across digital systems leads to time-consuming and error-prone processes.

To address this problem, this research explores how Model-Based Systems Engineering (MBSE) can be adopted to enhance SE processes of a contractor. MBSE is a modelling approach using a centralised system model consisting of interconnected sub-models. As MBSE has been adopted successfully in other industries, the construction industry continues to rely on the traditional document-centric SE approach. Therefore, the main research question of this research is: “How can Model-Based Systems Engineering be adopted to improve efficiency of Systems Engineering processes for a contractor?”.

This question is answered by first analysing existing literature on SE and MBSE. Continued by conducting interviews and an industry analysis to determine requirements for MBSE adoption, resulting in a selection of MBSE methods, tools, and languages suitable for contractors. In this way, an adoption proposal is created, including the change in digital landscape and information management. The tool Capella is used to model a case study project using MBSE principles. Finally, an expert session validates the benefits of the created MBSE models.

Key findings highlight MBSE’s potential to address some of the limitations of the current SE approach used by contractors. Furthermore, adopting MBSE requires careful consideration of implementing a MBSE tool and determining the single source of truth for each information element in the digital landscape. To realise the full potential of MBSE, information must be stored in models instead of documents. The added value of MBSE is validated by modelling a case study in the Capella tool and conducting an expert session. The main benefit of integrating a MBSE tool for contractors is a faster and higher quality design for disciplines using functional system behaviour. The modelling approach enables easier understanding of the system, more complete interface identification, faster impact analyses, and potential to enhance efficiency in the testing phase.

Challenges of this modelling approach consist of human resistance, integration with current system, expectation variations per discipline, management and responsibility of models, and additional design effort. Finally, the PARiHS framework provides input for the establishment of four maturity levels, which organisations can apply stepwise to effectively adopt MBSE.

The Architecture, Engineering, and Construction (AEC) sector is a major contributor to CO₂
emissions and resource consumption. In response, the Netherlands aims to make the sector 50% circular by 2030 and fully circular by 2050. However, the transition from a linear to a circular economy is complex due to technical, organisational, and cultural barriers. This dissertation explores how interorganisational behaviour and routinised practices within and beyond construction projects influence the realisation of circular ambitions. This research highlights the importance of top-down support, equal partnerships, shared goals, and intrinsically motivated individuals in construction projects. Trust, transparency, flexibility, and a shared team identity further foster the redefinition of traditional roles so as to drive innovation. However, factors such as focus on short-term cost and risk aversion often hinder progress. The dissertation further combines Sustainability Transitions Research (STR) and Social Practice Theory (SPT) into crossover frameworks that capture both systemic change and everyday practices. These are used to analyse (mis)alignments in the system-of-practices around construction projects. It was found that using secondary materials often clashes with notions of quality, safety, and aesthetics. Increasingly, Circular Building Hubs (CBHs) are brought forward as answer to this problem. This research shows that these hubs can be accelerators in the transition, though they are seen as temporary rather than permanent solutions. Ultimately, no single intervention will enable the shift to circularity. Instead, multiple coordinated changes in practices are needed. This dissertation provides tools for researchers and practitioners to navigate this complexity and encourages learning, experimentation, and a systemic approach to support sector-wide transitioning.

Global warming is primarily driven by the emissions of carbon dioxide resulting from human activities. The construction industry, driven by urbanization and population growth, plays an important role in this due to its resource-intensive nature. Buildings account for nearly 40% of global energy consumption and one third of associated greenhouse gas emissions. Additionally, the government’s goal for the Netherlands is to reduce greenhouse gas emissions by 55% in 2030 and to achieve climate neutrality in 2050. The focus to reduce CO2 emissions used to be on lowering operational energy emissions, but due to the increase in energy-efficient and net-zero buildings this focus is now shifting. As operational emissions drop, materials' emissions gain importance, shifting environmental studies toward reducing embodied energy.
One potential solution to address this challenge of reducing carbon emissions is the adoption of circular economy principles in the construction industry. Circular strategies, such as reduce, reuse, recycle, and recover, have the potential of minimizing waste, reducing resource consumption, and reducing CO2 emissions. However, it is unclear how these strategies compare to each other in terms of their carbon footprint.
Therefore, this research aims to assess and compare the embodied carbon benefits of the circular 4R-strategies with different structural materials in the building industry. Through life cycle assessments (LCAs) of case studies spanning a 40-year lifespan, the study evaluates the effectiveness of downsizing, reuse, and recycling strategies in reducing emissions. A 5% reduction in material use led to a 5-10% decrease in emissions, while a 10% reduction yielded a 9-16% reduction. The implementation of a moderate reuse strategy has been demonstrated to result in reductions in emissions ranging from 16% to 24% for timber and steel structures. Moreover, the results showed that it is possible to achieve significant emission savings of around 60% to 70% through the implementation of an extensive reuse strategy, where a greater proportion of materials are reused. The effectiveness of recycling strategies in reducing emissions varies considerably, with potential emission reductions of between 55% and 70% for concrete, between 27% and 70% for steel structures and between 12% and 37% for timber. The effectiveness of this strategy is highly dependent on the maximum percentage of recycled content the material in question can have.
A comparative analysis reveals that timber generally offers superior CO2 reduction over concrete and steel in the short term. However, concrete with an effective circular strategy and a lifespan of around 80-100 years can outperform a timber building with a lifespan of 40 years. Concrete with high recycled content and steel with significant reuse show notable CO2 reduction potential. Tipping points for concrete and steel structures occur around 80 years, where concrete becomes more favourable than steel due to lower replacement rates.
The research contributes to practice through the integration the study’s outcomes in design guidelines and a mathematical optimization decision model, that facilitate informed decision-making among clients, managers, architects, and suppliers during early design phases.

The Netherlands faces a need to increase renewable energy production to meet national climate goals, with solar PV electricity as a key component. However, recent reports indicate stagnation in solar PV growth due to financial uncertainty arising from the planned phase-out of the SDE++ subsidy scheme. This subsidy has historically provided financial stability by covering unprofitable segments in renewable energy business models. With its impending termination, large-scale solar PV projects face significant financing risks, which may hinder progress toward national energy targets.

This thesis investigates whether Power Purchase Agreements (PPAs) can mitigate financial uncertainty for solar PV projects in the absence of subsidies. PPAs are long-term contracts between energy producers and buyers that offer revenue predictability, essential for securing project financing. Drawing from the Dutch offshore wind sector’s success with PPAs in a subsidy-free context, this research explores if PPAs can fulfill a similar role for solar PV. The study employs a qualitative approach, combining desk research and 14 semi-structured interviews with industry experts, including policymakers, lenders, and developers, to validate propositions developed from the literature.

Findings indicate that PPAs are currently seen as valuable complements to subsidies, enabling higher debt leverage. However, several challenges limit their use as standalone solutions. The Dutch solar PV market currently lacks sufficient creditworthy offtakers, and the relatively small project sizes further complicate PPA viability. Additionally, the rising frequency of negative price hours, periods when electricity prices drop below zero due to market saturation, presents new new problems that PPAs alone may not fully mitigate. Although PPAs are currently not yet equipped to replace the SDE++ scheme entirely.

The research suggests that other measures, such as a PPA guarantee fund and adjustments in debt models, may be needed to ensure the financial sustainability of future solar PV projects. Limitations of the study include the qualitative methodology and confidentiality constraints, which restricted insight into specific PPA strategies. Among others, the findings underscore the need for additional research on alternative financing structures and the role of smaller offtakers in the Dutch PPA market, as well as hybrid solutions like battery storage to address price volatility.

Circular building adaptability (CBA) offers substantial benefits to the built environment, including reducing building costs through material efficiency and waste reduction, while enhancing the long-term value of structures through improved flexibility (Hamida et al., 2023). Next to this, CBA contributes to long-term sustainability in the built environment by making it possible to generate new business opportunities within the circular economy (CE). However, the Dutch building industry faces significant challenges in adopting CBA principles, particularly in the context of adaptive reuse (AR) projects. These challenges hinder the industry's transition towards a sustainable and circular built environment.

This research primarily concentrated on testing part of a relatively new framework that links determinants, strategies and the enabling and inhibiting factors of CBA in adaptive reuse projects to support the shift towards a circular economy. Accordingly, this study aimed to answer the following research question: “How can the applicability and effectiveness of design-oriented circular building adaptability strategies (CBASs) be promoted in adaptive reuse projects?”. A stepwise research design of two approaches was followed, namely case studies and Research-through-Design (RtD). The methods include archival research, field observations, semi-structured interviews with key informants, questionnaires, and workshops focused on practical design solutions.

The results indicate that the CBA-AR framework is a useful tool that integrates CBA-determinants, strategies, and associated enabling or inhibiting factors, and can be useful during early-stage planning and collaboration in adaptive reuse projects. Second, based on the findings of the case study, three strategies have been identified as the most applicable and effective, namely: opening the floor plan, providing multi-purpose spaces, and aligning the interconnection between floor plans. In contrast, the less applicable and effective strategies for the cases examined in this study are designing for mixed-use, modularizing spatial configuration, and designing for surplus capacity. Finally, the successful implementation of CBASs requires raising awareness among professionals, as the lack of knowledge often leads to missed opportunities for integrating adaptable and sustainable design strategies.

The scope of the research has been limited to the design-oriented (passive) CBASs, and therefore, directions for future research have been put forward in the conclusion. Moreover, the findings of this study are not generalizable because they are case-specific; however, they provide valuable lessons for future research, policy-making, and practitioners seeking to promote resource efficiency and future-proofing in adaptive reuse projects.

The circular economy is an economic model in which resources are circulated in a closed loop by adopting the R-strategies (e.g. reuse, recycling, and reduce) to minimize waste and pollution. Repurposing vacant buildings, known as adaptive reuse, is in line with the principle of circular economy, as it contributes to the reuse of the built assets instead of their demolition. In addition, this can help to conserve resources and reduce the environmental impact of building construction. Furthermore, adaptive reuse is not only necessary for vacant properties but also for obsolete buildings. Thus, it is an unavoidable practice in the built environment. This implies that adaptability should be incorporated into this kind of projects besides circularity. However, recent research revealed that many of the Dutch adaptive reuse projects were implemented without adequate consideration of circular solutions.
Accordingly, this research project aims to develop practical guidelines that could guide practitioners on operationalizing circularity and adaptability in the adaptive reuse of vacant and obsolete real estate.
Sequentially, three approaches with different research methods were followed to answer the main research question: ‘’How can circularity and adaptability be promoted in the reuse of vacant and obsolete real estate?’’
The first approach is the documentation of existing knowledge. This approach was followed to answer the first sub-question: ‘’What are the criteria and measures for reusing obsolete and vacant buildings in a circular and adaptable manner?’’ In this approach, a literature review was carried out. The literature review led to the identification of 12 criteria and 8 measures for circular and adaptable adaptive reuse.
The second approach is case studies on circular adaptive reuse projects of vacant and obsolete buildings. This approach was followed to answer the second sub-question: ‘’To what extent are circularity- and adaptability-related measures implemented in reusing vacant and obsolete buildings?’’ In this approach, three research methods were used in two case studies, namely: archival research, interviews, and field observation were used simultaneously. The findings of the cross-case analysis of two case studies resulted in adding 8 measures to the previously defined measures from the literature, totaling 16 measures.
The third approach is the formulation and validation of guidelines based on knowledge gained from theory and practice. This approach was followed to answer the third sub-question: ‘’How can guidelines guide professionals on how to promote circularity and adaptability-related measures in the reuse of vacant and obsolete buildings?’.’ In this approach, the guidelines were synthesized based on knowledge gained from the literature and findings of the two case studies. The results of developing and validating the guidelines contributed to adopting 13 guidelines. Overall, the validation outcomes indicate that the guidelines are informative and useful when visualized. However, they need to be updated constantly for their applicability in practice.

Digital Twin (DT) technology has transformed construction by creating virtual counterparts of real-world objects for improved project design and management. Integrating Building Information Modelling (BIM) with Game Engines (GEs) like Unity3D is crucial for effective DT implementation in construction. However, research in this area is limited, particularly in seamless BIM data exchange to GEs. This study bridges these gaps to enable successful DT deployment in construction.

This research addresses BIM-GE integration for construction DTs, evaluating commercial, customized and custom built data exchange methods between Autodesk Revit and Unity3D. Drawing from literature and commercial software, the methods are tailored to diverse DT use cases. The goal is to optimize workflows, enhancing efficiency and accuracy of data transmission between DTs implementing technologies. Findings provide guidance for seamless BIM-GE integration, fostering innovative and sustainable infrastructure.

Comprising four branches, the methodology involves a literature review to establish data needs for various DT applications, software pipeline evaluation, comparative analysis of data exchange methods, and prototyping using Dynamo.

Key findings include insights into DT use case requirements, analysis of data exchange method pros and cons, recommendations for DT development, and a practical prototype illustrating data exchange.

In conclusion, strategies for effective data exchange are highlighted, including bi-directional methods and real-time synchronization. Recommendations involve suitable file formats and polygon reduction techniques. Embracing emerging technologies like object behavior and sensor data enhances DT simulations. This research demonstrates how the DT use case influences the type of data need and therefore highly affects the data exchange methods to be considered when developing a DT.

One of the crucial aspects of BIM is the data rich environment connecting project information from different sub-sectors. (Mesároš et al., 2020). Therefore, developing models with consistent and trustworthy building data has gained significant importance in the industry. In contrast, incorrect or incomplete building data in a model could result in chained mistakes across disciplines, rework, or inadequate models for other stages of the building lifecycle.
Most of the improvements in BIM data in organisations take place in data quality reviews by BIM specialists. The lack of integration and complexity of existing data checking tools raised the expertise leading to assessment tools used mostly by BIM specialists. After a specialist reviews a project, corrections are communicated to the designers to solve the data issues in their models. This process is repeated until the desired quality is reached by the design team. Furthermore, missing, or wrong basic data structure can often lead to incomplete or inaccurate data checking processes.
The higher goal of this research is to produce perceivable benefits in the organisational data checking process. This is approached by facilitating the implementation of BIM standards and increasing the compliance of objects during design periods before entering the organisational review. Previous research showed that professionals would prefer to use simple dedicated quality checkers that can minimise manual tasks precisely and reliably instead of advanced software solutions. Thus, the goal is not to replace current workflows and practices, but instead to enhance basic data structures in models before entering the data reviews, by developing and implementing a new design-integrated checking and reporting tool.
The new checking process was verified and validated with specialists and modelers in three ongoing projects. This research showed that the developed design-integrated tool can produce the perceivable benefits in the organisational data checking process explained below:
•Enhancements in data quality before and after regular organisational checking reviews.
•Decrease in the duration and iterations in the organisational reviews.
•Increase of effectiveness and efficiency in detection and correction of data quality issues.
•Decrease of personnel frustration in the organisational process.
Thus, the research fulfilled the main objective to produce perceivable benefits in the organisational data checking process by developing and implementing a dedicated solution that engages designers in the process. The role-specific approach was essential to achieve a solution that meets the specific needs and system requirements of the target group, the designers. The purpose was to add a new prechecking layer to support and enhance existing data quality practices and processes. The result was a steering instrument for modelers working on the detailed design phase to involve them in identifying and correcting data quality issues.
Although the perceived benefits may vary in different contexts and organisations, the new data checking and reporting solution would raise awareness and promote designers’ engagement in the organisational data checking process, who are in a dominant position to identify and correct data quality issues.

As climate change and resource shortages increasingly threaten our planet, the built environment sector is under scrutiny due to its significant contribution to carbon emissions and global raw resource extraction. A transition towards a circular economy, replacing the prevailing "take-make-dispose" model, is crucial. This research explores the concept of Product-Service Systems (PSS) in the built environment, wherein products are provided as services, thereby increasing supplier responsibility and closing the resource loop.
This study answers the research question: "How can Product-Service Systems (PSS) be applied in the built environment and expanded to their fullest potential?" It delves into the various characteristics and properties of products within PSS and factors influencing these systems. Furthermore, it analyses the roles of different stakeholders within the circular chain of PSS, current implementation of PSS in the built environment, and future possibilities.
Adopting a qualitative research method, the study begins with an extensive literature review to provide an overview of current concepts and existing PSS models. This review forms a basis for identifying critical properties and characteristics necessary for successful PSS implementation. In-depth interviews with experts further provide insights into potential new opportunities for PSS in the built environment.
The research highlights the modularity, environmental sustainability, and economic viability of various building products, ranging from windows and doors to smart building technologies. A comprehensive table analysis reveals the potential for PSS implementation and the degree of circularity for these products. This research contributes to the field by presenting new possibilities for expanding PSS in the built environment. It emphasizes the need for pilot projects to better match practice with literature, increase the understanding of individual products, and uncover currently unknown factors. By enhancing our knowledge of PSS, this study propels us one step closer to achieving a circular economy in the built environment.

The climate crisis and resource scarcity have compelled industries to adopt new environmental and circular standards. The Netherlands has set a goal of achieving a fully circular economy by 2050, with a 50% reduction in the use of primary raw materials by 2030. In the circular built environment, circularity strategies like reuse are being implemented to reduce waste and carbon emissions. However, only about 1% of the building products that can be reused in The Netherlands are currently being reused for another lifecycle. This thesis aims to investigate the relationship between the technical aspects of reused building products and their reuse potential, which has received limited research attention thus far. To address this gap, a theoretical framework for assessing reuse potential is built through a literature review. A sampling study of over 30 building products is then conducted to evaluate their adaptability potential and disassembly level, generating a systematic overview of the technical aspects that influence reuse potential. The results demonstrate that refitability, adaptability, scalability and disassembly level are the most important aspects in determining the reuse potential for posterior lifecycles. By providing a deeper understanding of the technical aspects influencing the reuse potential of building products, this thesis aims to contribute to the development of circularity strategies in the built environment.

The increasing significance of the circular economy in the real estate construction industry is driven by evolving environmental, social, political, and economic factors. While there is increasing pressure for a national transition to a circular building economy, the sector continues to confront numerous challenges, risks, and uncertainties. To promote pro-circular decision-making among project management stakeholders, this research investigates how incentives need to be implemented in order to be an effective strategy to encourage project management stakeholders in making pro circular project decisions.

During the research an overall research strategy, the systemic design toolkit, has been used. This method integrates systems thinking with a human-centered, multi-stakeholder focus, by addressing the intricate social, economic, and environmental aspects of the issue at hand. The study comprises two sections: a theoretical segment employing quantitative research and an empirical segment employing qualitative research.

The theoretical phase explores the interorganizational dynamics that influence circular decision-making, delves into the roles and perspectives of project management stakeholders, and examines the concept of incentives. The empirical phase starts with semi-structured interviews to gain insights into the behavior, intentions, interrelationships, interests, and influence of relevant actors involved in decision-making processes. Subsequently, unstructured brainstorming and validation interviews are conducted to identify and develop effective incentives within the financial, social, and moral clusters.

The research findings provide empirical evidence that incentives can serve as a viable strategy for motivating project management stakeholders to make pro-circular strategic project decisions. These incentives are integrated into a comprehensive incentive scheme, outlined in the concluding section of the findings. Through the adoption of these incentives, stakeholders can be effectively motivated to embrace circular principles and actively contribute to the establishment of a circular building economy. Additionally, some key variables have been identified as influential factors in the success of the incentives: the involvement of supplying stakeholders and the targeted audience, as well as a thorough understanding of the rationale behind circular project rejection, the prevailing power dynamics, and the degree of stakeholder involvement throughout the various design phases.

In recent years, the housing market has been under pressure due to growing demand for (inner-city) housing and a lack of supply. Housing is in high demand as a result of factors such as population growth, rapid urbanization, smaller households, the freezing of "mobility in houses, and so on. The low developing speed to cater to these issues might instigate an investigation into possible adjustments to the current building methods to increase the rate of housing production.

The building sector has the potential to fulfil these demands by becoming more product-driven, efficient and sustainable, which are said to be attainable with the use of modular construction (Bertham et al., 2019). However, traditionally, the building industry is characterized as a project-driven industry with unique characteristics such as location-bound design, one-of-a-kind/unique production, changing partnerships per project, outdoor and environmental factors, and multiple clients and suppliers involved in a single project. These characteristics conflict with the product-driven ambitions, leading to negative effects on performance such as low levels of effectiveness and efficiency, low rates of innovation and difficulties in knowledge sharing and learning.
This research explores the potential benefits of vertical integration in modular construction value chains. The study is based on an empirical single case study of an integrated modular building company in the Netherlands. The case study examines the implementation of vertical integration in the modular building company, and its impact on the project- and product value chains.

To achieve effective vertical value chain integration during the development phase, the industry needs to focus on synergy, competency, and organization and adopting the appropriate production system fitting to their organization, product and production profile. Synergy involves establishing a clear and structured collaboration structure between departments, early involvement of key parties, and having a systematic approach to the project. Competency involves having adequate experience in the modular construction industry, defining a modular design system with configurable designs, and focusing on modular design systems with configurable elements, design flexibility, and efficient and streamlined production processes. Organization involves establishing unambiguous guidelines and expectations for each phase of the project, creating a comprehensive project plan that clearly defines the roles and responsibilities of each team member, and identifying the primary coordinator for each phase. Additionally, it is essential to have a supportive and collaborative company culture with trust among employees, morale and motivation, and leadership that encourages and facilitates cooperation and collaboration across different departments and locations for all factors to thrive.

Based on the modular construction goal, fitting product and production characteristics were explored, which resulted in defining appropriate production systems. The focus on modular design systems with configurable products and the need for design flexibility described in the product description align with the characteristics of assemble-to-order production. The emphasis on product-oriented and project-oriented approaches, as well as the need for design consistency and efficient translation to production, aligns with the characteristics of make-to-order production.

In project-based organizations, enhancing performance and augmentation of project value rely heavily on the effective assimilation of past experiences. Nevertheless, the intricate nature of projects and time constraints present extra challenges for an effective learning across various project teams. Inter-project learning, particularly in the context of specialized teams, increased complexities, and limited interactions, become more challenging. This thesis endeavours to propose innovative approaches that aim to help project-based organizations to improve their inter-project learning processes.
This research addresses a critical gap in the literature, as there is limited existing research on inter-project learning within project-based organizations. The study begins with an extensive literature review encompassing organizational learning, project-based organizations, and inter-project learning. Based on the literature study, a hypothesis model has been developed. This model categorizes the factors into three main categories: barriers, facilitators, and influencing factors. Moreover, the factors are classified into three dimensions, each representing components that constitute the learning infrastructure mechanisms, knowledge accessibility, or organizational culture.
Following this, empirical research took place through a case study within the organization under study. The case study focused on understanding the organization's existing approach to inter-project learning and involved interviews with experienced project managers to gain deeper insights into inter-project learning processes. The findings shed light on the continuous need for improvement in the inter-project learning process. The results suggest that the factors impacting inter-project learning can be classified differently than merely as barriers, facilitators, and influencing factors. Instead, they can be classified as factors into four structural domains. These domains encompass technological, social, organizational, and industrial. Each domain represents various aspects that can be covered by the organization and each domain offers a more nuanced understanding of the factors that shape the dynamics of inter-project learning.
The research presents a roadmap framework that guides project-based organizations on what steps they need to undertake to improve inter-project learning. Utilizing this roadmap framework will assist organizations in enhancing performance and eventually increasing project value as a result of the effective utilization of the learning processes. This roadmap can be used as a starting point to optimize inter-project learning and knowledge exchange processes and eventually improve performance and augment project values.

This research aimed to determine whether offsite construction leads to a lower environmental impact than onsite construction. Further, it is researched how the environmental impact of offsite construction can be reduced. This is of great importance as the construction industry has a significant environmental impact. Specifically, offsite construction is extra relevant as the Dutch government chooses to stimulate offsite construction methods for its lower environmental impact.

First, relevant information about offsite construction methods and environmental impact assessments are researched by literature study. The environmental impact of 2D panelized and 3D volumetric construction is likely to differ as the amount of work offsite and transport logistics are different. Then, the MPG is selected as the method to assess the environmental impact. This tool measures the environmental impact of building materials throughout their lifetime. An MPG calculation is needed to obtain a building permit for residential buildings.

Next, the differences between the following construction methods are compared and studied: onsite construction, modular offsite construction and panelized offsite construction. This is done through case studies of each of these construction methods.

The cases were compared on their differences in construction methods with a focus on differences in materials and processes.

The cases were then compared on their environmental impact through the MPG calculations. The scope of the MPG was limited. Services and space plan (like kitchens and toilets) as described by Brand (1994) were left out of the assessment. Interior walls and doors however, were part of the assessment. The calculation showed that the environmental impact or the MPG was highest for the onsite case and lowest for the modular case. Offsite construction did come with a lower environmental impact than traditional construction in this study.

Four strategies were identified after looking into the MPG comparison done in this research and in two other comparisons done by other researchers to lower the MPG.
To bring down the environmental impact:
1. Limiting the use of materials
2. Choosing different materials

To bring down the MPG score:
3. Use more cat 1 or 2 data
4. Enter a longer lifespan for a building

Subsequently, these 4 strategies are tested on their viability and effectiveness in the case of Leerpark Dordrecht.
Strategy 1 was not feasible in this specific case, the other 3 strategies proved viable and effective. These strategies would lead to a 29% reduction in the MPG compared to the MPG made earlier in this research.
However, there are limitations to the MPG when comparing the environmental impact of different buildings:

• The material-based approach does not allow to account for the design as a whole.
• The NMD is lacking data. There are not enough cat 1 or 2 items available in the NMD.
• The energy performance of buildings is often enhanced by using building elements that negatively impact the MPG, like solar panels or insulation panels.
• The MPG does not help lower construction emissions now as the embodied energy is spread over 75 years.
• Biobased materials are not fairly assessed in the current system.

The Netherlands currently suffers from a housing shortage, which cannot be solved by the traditional project-based approach of realizing new homes. Under a visible trend of a project-transcending, programmatic approach within the construction sector, various housing associations, municipalities and market parties are united in an inter-organizational collaboration to combat the shortage of social rental housing. These have led to various regional social housing construction programs, the Bouwstroom (Dutch translation for construction flow). Since program management requires an appropriate approach for each specific program, there is a need to better understand and further develop the current application of this management concept in the Bouwstroom programs for this context. Program managers should guard against a too one-sided focus on either control management, because this is too robust for a programmatic collaboration, or interaction management, because this leads to too slow progression and expensive ideas. The solution is to complement the two approaches with each other, in which an appropriate ratio of both approaches is context-dependent. To counter interaction or control related challenges, mixed strategies should be applied over time and a right structure is necessary in the organization. Furthermore, the literature speaks of six attributes of effective program management: 1) the vision, 2) priority focus, 3) planning framework, 4) governance, 5) coordination and 6) adaption. These attributes must be applied appropriately for each program for program management to function effectively. Two representative case study programs, WoonST and Bouwstroom Noord, are analyzed. A cross-case study has made it clear that the current application of program management in both cases leads to external interaction challenges in particular. Where the internal parties are aligned and motivated, there is still a hindrance from parties that are not part of the Program Management Office, but still influence the course. This results in the municipalities being limited in their role to speed up the processes. In order to create more value of the programs, the major challenges need to be mitigated. Multiple interaction-type strategies suggested from the literature are validated to mitigate them, several of which have not been applied before. However, they still need to be balanced with control strategies, of which those proposed from the literature mostly score poorly. This indicates that the need for additional complementary control measures is still present and does not seem to be satisfied by the study's findings. This study confirms the theory that program managers should maintain an appropriate interaction and control focus, despite a short-term detriment to the process. In addition, this research shows that program managers must continue to learn. By analyzing strategies from your own program, programs from other Bouwstroom programs and even programs from different contexts, and reflecting on a specific context, unique challenges can be approached more accurately. New strategies should be learned in order to approach unique challenges more accurately.

In the built environment, the continuous growth and expansion of urban areas worldwide have become alarming. The built environment is continuously developing in an unsustainable manner, and in the mid-term future, resources will be scarce if practices are not changed. Therefore, new building materials and methods need to be implemented to mitigate the substantial problem and prevent a point of no return. This research focuses on the Global South taking Kenya as a single case study to investigate the following research question: How can NGOs support local stakeholders in Kenya to shift the production of affordable housing by the use of circular materials and methods? This research design was conducted through a double-diamond framework, and data was collected in a qualitative manner. The objective is to understand housing practices in the local market to seek alternatives to shift affordable housing development into circular practices. By these means, this research attempts to provide information on the processes of support that NGOs can give to implement circular materials and methods in housing, strategies to create acceptance and adaptation of these materials in the local market and the ways to create economic and social value through circularity in the built environment. A comprehensive literature review was made to develop a foundation of knowledge for the empirical study.

Furthermore, as a result of the empirical study and the triangulation of data between the literature review and the research findings, a guideline for NGOs to help local stakeholders shift to circularity was created. The output of this study endeavours to develop an understanding of how the demand and the supply of circular materials and methods need to be tackled to be able to disseminate circularity in the local built environment and create the shift towards the use of these innovations and new building practices. As a result, the depletion of natural resources and the amount of CO2 emissions produced by the built environment in Kenya can be controlled while providing affordable and adequate housing for the country.