This thesis investigates the adoption of circular design principles by engineers for the design of wastewater treatment plants for Water authorities, by exploring hindering and stimulating factors involved and applying the Behaviour Change Wheel (BCW) to develop strategic interventions for engineers at the case study consultancy firm Royal HaskoningDHV (RHDHV). The research problem addresses the challenge of integrating circular design principles into wastewater treatment plants, aiming to enhance circularity practices within engineering consultancy firms. The main research question is “How can the adoption of circular design in wastewater engineering consultancy firms be enhanced using the Behavior Change Wheel?” The objective is to gain insight into the key actors, the perception and engagement with circularity among RHDHV, the barriers and facilitators to the adoption of circular design and to propose strategic interventions using the Behaviour Change Wheel.
The research employs a qualitative research method, including a literature review, informal conversations, and semi-structured to open interviews with employees from the wastewater department of Royal HaskoningDHV. The collected data was analysed using thematic double coding, comprising an inductive explorative approach, and a deductive approach based on the Theoretical Domain Framework (TDF). The BCW framework was applied to identify behaviour change techniques (BCTs) and interventions that stimulate engineers to make more circular design choices in every phase of the project by considering and selecting materials and design choices that are reducing, reusable, recyclable, and demountable.
Key barriers to the adoption of circular design practices include limited knowledge, unclear principles, insufficient evidence of technical functionality, reluctance from clients, a preference for traditional design approaches, and budget constraints. On the other hand, facilitators include circularity workshops, partial integration into design processes, management ambition, and existing sustainability initiatives. Active client support and dedicated time for circular design are essential.
The BCW approach identified 43 behaviour change techniques beneficial for promoting circular design, from which a balanced selection addressing capability (knowledge and skills), opportunity (design routines and tools), and motivation (confidence in circular designs) is recommended. The recommended interventions for the specific case study are (i) comprehensive training sessions and educative materials on circular design, (ii) establishing clear, achievable circular design goals, (iii) a focus on projects with clients committed to circular design, (iv) establishing a helpdesk or expert team for practical and social support, (v) incorporating circular prompts and cues into project planning, and (vi) monitoring progress while showcasing successes and providing feedback. Although tailored to Royal HaskoningDHV, these interventions can serve as a guideline for other firms, with necessary adjustments for different contexts and client relationships.
The study highlights the significance of targeted, practical interventions and raises new questions about the balance between sustainable and functional requirements, re-evaluating comfort and budgetary requirements and the need for further development of practical tools and guidelines.