Citizen participation is vital in the design and implementation of new technologies. In the ENaQ project, a long-term participatory process is applied to accompany the development of a new energetically efficient residential quarter in the city of Oldenburg. This chapter shows how different participatory formats were used to involve the public at different stages of the project. We shed light on limitations to citizen participation in the context of technological developments in the housing sector including the fact that future residents are not known, the highly technical topics, limitations set by external framework conditions, conflicting interests and contact restrictions due to the Covid-19 pandemic. To share our learnings with similar projects, we examine how these hurdles can be overcome, and identify the following success factors supporting effective participatory processes: (1) thorough participation in an early stage, (2) the presence of planners and decision-makers at participation processes, (3) combining technological and social benefits, and (4) the institutionalisation of participation.