The number of raw materials consumed and waste generated by the construction industry is no longer a viable solution in the future. It is required for the construction industry to move from a linear towards a circular economy (CE) by circular construction (CC). The unfamiliarity in actions that need to be taken for CC is still new terrain for many companies since the whole life cycle of a project needs to be considered and is plagued with technical, legal and cost issues that obstruct CC.
Contract forms such as Early Contractor Involvement (ECI) involve contractors in the design phase of a project, such as suppliers, builders, and demolition contractors, to engender a better design by sharing and creating new knowledge. There are, however, no sources directly indicating that the benefits of ECI also regard circularity. At the same time, issues that emerge with CC remain an obstacle for fully transitioning to a CE.

This research aims to understand better the issues regarding CC and if ECI would be beneficial in solving them due to the knowledge contribution of contractors and their collaboration with other parties in the design process. Therefore the research question is framed as follows: “How is contractor’s knowledge contribution improving circular construction in ECI context?”

The research consists of a literature study and an empirical study. First, the literature study was conducted to define the relevant concepts such as ECI, CC and knowledge processes. Next, to understand the knowledge contribution of contractors to CC in the design process, interviews with practitioners involved in CC projects were conducted according to the Critical Incident Technique (CIT). In CIT, research participants are asked to recall and describe a time when a behaviour, action, or occurrence impacted a specified outcome positively or negatively.

From the empirical study, there can be concluded that contractors' knowledge contribution plays an essential role in the feasibility of a circular design solution. However, the dynamics in collaboration between multiple parties can lead to better circular results. Since the collaboration can result in knowledge creation and sharing, developing a good work relationship between contractor and client and problems can be jointly solved when there is mutual support. This, however, also requires trust and transparency between the parties, and if lacking, it can obstruct CC.