Gewobag, one of Berlin's leading state-owned housing associations, is restructuring the management of its energy services company. Dipl.-Ing. Gunnar Wilhelm has been appointed Managing Director of Gewobag ED, effective 1 July 2026. He will hold this position jointly with Martin Mahlberg, succeeding Karsten Mitzinger, who is retiring.
With Gunnar Wilhelm, the leadership team gains a proven expert in energy services and the heating transition. His expertise also extends to the technical implementation of complex real estate and infrastructure projects. Before joining Gewobag, Mr Wilhelm served as Managing Director of GASAG Solutions Plus GmbH from 2019 to 2025. In this role, he led the heating transition and energy services business for the entire GASAG Group, an established player in the German energy market.
Extensive Expertise in the Energy Sector
During his tenure at GASAG Solutions Plus GmbH, Gunnar Wilhelm was responsible for a wide range of tasks. These included the development of decentralised energy concepts and the creation of decarbonisation roadmaps for the heating, cooling and electricity sectors. Furthermore, he was responsible for the operational management of nearly 1,000 customer installations located in Berlin, Brandenburg, and nationwide. These previous activities demonstrate his comprehensive professional and operational knowledge in the energy industry.
Markus Terboven, Gewobag's Executive Board member, commented on the new appointment. He highlighted that with Gunnar Wilhelm, Gewobag is gaining a leader who combines energy industry competence, technical expertise, and long-standing management experience. Mr Terboven emphasised that Mr Wilhelm, together with Martin Mahlberg, will further develop Gewobag ED and provide pioneering impulses for a secure, affordable, and climate-friendly energy supply for Gewobag's neighbourhoods.
Tribute to the Outgoing Managing Director
Prior to his role at GASAG Solutions Plus GmbH, Gunnar Wilhelm was active as Managing Director of BAS Kundenservice GmbH & Co. KG, a subsidiary of GASAG AG. Before these positions, he was responsible for the operational customer business of Vattenfall Europe Kundenservice GmbH for many years and took over as Chairman of the Management Board from 2011. These career stages underscore his profound experience in energy management and customer service.
The outgoing Managing Director, Karsten Mitzinger, has significantly shaped the development of Gewobag ED over an extended period. Under his leadership, essential foundations for a professional, efficient, and neighbourhood-focused energy supply within the entire Gewobag Group were established. Markus Terboven thanked Mr Mitzinger for his commitment, his professional expertise, and his reliability, which contributed to the further development of Gewobag ED as an important component of the group of companies. Gewobag wishes him all the best for his upcoming retirement.
- —New appointment of Gunnar Wilhelm to the management board of Gewobag ED, effective 1 July 2026.
- —Gunnar Wilhelm brings extensive expertise in energy services and the heating transition.
- —Karsten Mitzinger, who significantly shaped Gewobag ED, is retiring.
- —The goal is a secure, affordable, and climate-friendly energy supply for the neighbourhoods.
