While research on the sustainable built environment has acknowledged the need to integrate multidisciplinary perspectives in the early planning phases, few studies have focused on early-phase meetings and how these can support such co-creation of sustainability. In this study, a set of "characteristics" for collaborative meetings integrating multidisciplinary perspectives was tested in 16 meetings that took place in the early phase. An action research insider perspective was used, where a researcher was also the facilitator of these 16 meetings. The cases provide insights into the early-phase processes where the building industry can achieve sustainable impacts on the built environment. This was exemplified by two of the cases becoming demonstration projects in terms of sustainability. Empirical material was gathered through discussions and surveys with meeting participants and was analyzed through the lens of the meeting design characteristics. The findings show that processes with 'soft' interpersonal characteristics (expressing emotions, tempo change during dialogue, engaging in social interaction, moving the body) support the development of a shared understanding of sustainability that integrates multidisciplinary perspectives. For larger groups and in digital meetings, a combination of 'soft' (interpersonal) and 'hard' (digital communication tools and platforms) characteristics were found to be supportive, especially when the meeting time was limited. This research suggests a revision of the design of multidisciplinary early-phase meetings towards including social, emotional, bodily, and collaborative exercises supported by digital tools.