De*sign and planning process of “green buildings” requires a fundamental change in traditional design planning process, towards more integrated, collaborative practice with life-cycle orientation. The methods known from aeronautical and automotive industry such as concurrent engineering have often been referred to as possible way for radical process improvement of AEC industry, however the implementation of the so called integrated building design (IBD) in the planning practice has not succeeded yet. This paper will present the results of the multiple case study research of best-practice planning processes for five energy efficient buildings, with aim to determine the success factors, optimization potentials and deficits of the processes. The findings identify the early evolvement of stakeholders, interdisciplinary, simultaneous collaboration and transparency in communication and information as success factors. The findings were verified in the practitioners’ workshop, where as particularly important step for the implementation, the change of fee structure for architects and engineers (FSAE) and scope of services were identified.