Timm Sassen (49) is the founder and owner of the Greyfield Group, Chairman of the Greyfield Foundation, and a founding initiator of the Association for Building in Existing Structures.

He calls for an end to the throwaway mentality and places the focus on existing building stock. With projects such as the “CO₂ Certificate” and the “Greyfield Index,” he is advancing the practice of building in existing structures. Among other activities, he is involved in the Association for Building in Existing Structures and demonstrates through Greyfield’s own projects that working with existing buildings can be both ecologically and economically beneficial.