In the face of growing social and environmental challenges, design is increasingly concerned with addressing complex systemic issues (Ceschin & Gaziulusoy, 2016). This dissertation explores how design can foster societal transitions with a dual focus. First, it develops transformative strategies for the plant-based protein transition, an urgent shift given its environmental, health, animal-welfare, and justice implications, and its cultural and behavioural complexity (Béné et al., 2020). Second, it investigates systemic breakdown, a ‘forgotten half’ of transitions often overshadowed by innovation (Hebinck et al., 2022), and delivers a research agenda around design for decline...

Sustainability transitions are inherently comprised of wicked problems, requiring new
systemic problem-solving approaches that transcend disciplinary boundaries. Design
framing is a practice that lies at the core of problem-solving, as it connects a specific problem
to a promising solution space. We contribute to transition design research by conceptualising
a transformative design frame. Anchored in the fields of design, sustainable behavioural
science, and transition studies, our transdisciplinary model is intended to support transition
designers in their reasoning and to inspire the development of novel frames to help
accelerate sustainability transitions. The model visually organises several building blocks of a
design frame: Transition Case, Transition Strategy, Systemic Levers, Behaviour Change, and
Worldview. To evaluate our model in various transition design contexts, we held review
sessions with three Dutch design agencies, followed by a framework analysis of their
responses. The results informed a revision of the model and demonstrated that the model
supports designers in building a stronger design rationale, which the designers expected to
benefit stakeholder alignment and mobilisation in transition contexts. After engaging with
the model, participants intended to adopt a more comprehensive and systematic framing
approach in future projects. To bring the model to a higher level of maturity, opportunities
for further research involve applying it in practice. As such, we can examine more thoroughly
how the model might support reframing and explore which combinations of its components
could be most transformative.

Excessive animal protein consumption has led to calls for a plant-based protein transition. Plant-based diets can be fostered by design interventions, yet their effect on dietary choices depends on the framing that is chosen. The aim of this study was to understand which transition design frames (TD frames) are prevalent in existing consumer interventions in the Netherlands, to help transcend the dominant substitution pathway with alternative strategies for intervention. We explore framing through the lens of design, examining human-made interventions in a transition context, to complement the discursive lens that is common in transitions literature. Based on 62 existing consumer interventions and eight expert interviews, we identified eight TD frames. We find that market regulation and cultural interventions are strategic avenues to pursue. Reframing opportunities involve inclusivity, system breakdown and integrating multiple frames into single interventions. We observed that a design lens helped elucidate frame types that have not previously been identified in transitions literature.

Meat and dairy mimicking has been the most popular strategy in the plantbased protein transition, representing a dominant 'design frame'. These analogous products come with several risks. Complementary to transition studies, design considers behavioral and material dimensions of the environment influencing consumers' dietary decisions. By analysing existing consumer interventions in the Netherlands, we seek to identify prevalent design frames ('i.e. strategies for intervention') in the Dutch protein transition. We elucidate and examine alternative pathways to foster the transition, informing on more effective ways forward.

Many of our daily behaviours, e.g., our choice for transportation and our consumption behaviours, need to change in the light of the pressing sustainability issues we are facing. Yet, while many people value the environment, they do not always engage in the behaviours that are in line with these values, representing the so-called ‘value-action gap’. This paper argues that the value-action gap can to a large extent be explained by a choice architecture which promotes unsustainable behaviours. Therefore, we present a redesign of choice architecture in the context of meat consumption, to stimulate people to act in line with their values. Our experimental study shows that such a redesign leads to a significant increase in sustainable behaviour, without conflicting with people's values. This opens the discussion on how we design the architecture for such choices and adds granularity to the moral debate about nudging.