Energy providers face several technical and societal challenges with respect to renewable energies and smart energy systems. As central management units of energy supply systems, control rooms and their operators are especially affected by those changes. While reliability and safety of software systems for managing electric power grids is of utmost importance, their usability has to be ensured as well in order to allow for safe and efficient operations. Previous work has failed to address issues of work reengineering and user interface design for future smart energy control rooms due to insufficient collaboration of human-computer interaction researchers, energy informatics researchers and energy sector stakeholders. This paper describes challenges and approaches for ensuring usability of future smart energy control room systems. It is based on a human-centered design process within an interdisciplinary research project bringing together the aforementioned groups of experts. Results were derived from systematic literature review, workshops and surveys with control room operators as well as contextual inquiries in three control rooms. They concern both the process of realising software systems for managing electric power grids and applications characteristics with respect to user interface design. It is concluded that open and modular software systems require consistent user interfaces based on a style guide. Furthermore, software and usability engineering processes of energy control systems have to be aligned in order to ensure usability, safety and security.