Sustainability demands have changed the building design nature, which gained complexity due to the increased diversity of requirements, activities, agents, and tools. Building Information Modeling (BIM) has a potential to contribute to sustainability enabling the building integrated design, performance simulations, life cycle assessment and information use throughout the building life cycle. The aim of this paper is to investigate the sources of challenges in the relation between architectural and engineering (AE) design firms and clients (developers or private individuals) for promoting sustainability in the building design. Also, it is investigated if BIM has been implemented by the firms and how it relates to management and sustainability. The research method adopted is qualitative and participatory based on focus groups. Two groups were interviewed: eight AE design firms and six developers and/or construction companies. Analysing the research findings, the sources of challenges that were identified are the lack of definition and communication about the stakeholders’ sustainability approach; the lack of a more detailed design scope and required qualifications by the clients, but also the lack of business management and firm’s performance evaluation processes by designers; the traditional project delivery systems, traditional work relationships, tools and processes that do not support the collaboration needs. In addition, AE design firms’ organization affects the client relationship and design quality including the consideration of sustainability issues in the design solutions. The sources are found in the AE design firm’s processes of strategy planning, business and marketing, design, people, and knowledge management. So, further research will be carried out about managerial and organizational capabilities of AE design firms for sustainability and BIM.