Consulting Engineers and Architects are currently experimenting with the concept of “Integrated Design Process” (IDP). This paper views Integrated Design Process as a process tool and a concept for management and organization of the green energy engineering process. Moreover such a concept is understood both as systematic knowledge and a symbolic device for enabling change. The paper briefly review international variants, and focus on two variants present in Denmark: an architect and engineering variant of IDP. The differences between the concepts include different roles for main actors, the use of information technology, the relation to lean, and forms of collaboration. The paper discusses two building projects focusing on teams of engineers and architects in the early conceptual phase. One develops a solution focused on energy saving technologies, the other on energy producing. It is argued that in this practical context, IDP is viewed as ambiguous and not well defined, and the architects and engineer work hard understanding and using the concepts even when directly involved. It is difficult to reach consensus on how to do it. The various players agree that an increased interdisciplinary interaction in the design team is necessary in order to comply with the increased complexity of green energy building design. IDP shows potential as a driver for green energy engineering and technologies, as traditional roles and responsibilities in the design process is changed, and sustainable solutions for green buildings can reach a higher standard and quality and are integrated earlier in the design process.