Tackling current sustainability challenges requires substantial societal and social changes, and many different strategies for their deployment. More people have to choose sustainability practices, such as sustainable mobility practices, but such transitions are not easily accomplished. Everyday life is formed by, on the one hand, available systems of provision and, on the other hand, chosen lifestyles. Design can influence conditions for these systems and lifestyles, and thus enable more people to embrace sustainability practices. However, for this to happen, design practice in itself needs to be reformulated to include everyday practices as design material and address the associated dynamics and complexities.

This thesis presents suggested reformulations of design as a practice through the RE-DO Design engagements. The suggested design approach is built on three research projects that staged interventions in sustainable mobility practices. Through practicebased design research, and with a design research program, possible reformulations of design practice to create favourable conditions for sustainability practices have been explored. RE-DO Design comprises design doings, strategies and postures, and involves iterative design work in four loops that respectively reconfigure, perform, explore and bridge sustainable proto-practices. Each iteration includes design strategies for these doings and enables opportunities for revisioning and learning in everyday life as well as for decision makers. To realise RE-DO Design, three design postures are suggested: Re-make, Re-value and Re-learn. With these reformulations of design, conditions for sustainability practices can be influenced and designed.

The thesis discusses RE-DO Design, with the mobility interventions as a basis and with a focus on the three design postures Re-make, Re-value and Re-learn. The aim is to contribute to developing and reformulating design as a practice in order for it to play an important part in sustainability transitions.