Redevelopment – Möglichkeiten und Chancen, unrentabel und unfunktionell gewordenen, innerstädtischen Bürohausbau der Fünfziger, Sechziger und Siebziger Jahre zu Wohnraum umzunutzen (Abschlussbericht)

The report “Redevelopment – Möglichkeiten und Chancen …” is a comprehensive final study commissioned by the Bundesamt für Bauwesen und Raumordnung (Federal Office for Building and Regional Planning) under the Zukunft BAU research initiative. Authored by architecture historians Gert Kähler, Bernd Kritzmann and architect Carsten Venus, the work examines the conversion of outdated inner‑city office buildings from the 1950s‑70s into residential use. It was completed in 2009 and is publicly available as a completed, AI‑generated publication.

The study aims to assess the economic and ecological potential of repurposing obsolete office blocks into housing. It investigates market size, technical feasibility, legal conditions and demand for such conversions. The methodology combines literature review, questionnaire analysis, case studies from German cities (e.g., Hamburg, Stuttgart, Düsseldorf) and international examples, as well as expert interviews. Data were gathered through a structured questionnaire and field surveys conducted by the research team and partner institutions.

• Approximately 1 million m² of vacant office space in Hamburg alone could accommodate roughly 25 000 people if converted to residential units.
• Similar unused office stock exists across German metropolitan areas, indicating a sizeable national conversion potential.
• Conversion projects have already been implemented in several cities, demonstrating a growing trend toward inner‑city residential densification.

The report outlines typical construction characteristics of mid‑20th‑century office buildings, such as rigid floor plans, limited ceiling heights and façade systems from the 1950s‑70s. It identifies necessary adaptations for residential use, including upgrades to building services, compliance with modern fire‑safety standards, and re‑configuration of interior layouts to create flexible living units. Energy‑efficiency measures and climate‑protection strategies are highlighted as essential for sustainable redevelopment.

Cost analyses reveal that redevelopment can be financially viable when public funding, subsidies and partnership models are employed. The study notes that conversion costs are often lower than new construction because the structural shell is retained, reducing material consumption and land‑use pressures. Funding from the Zukunft BAU programme and other federal sources underpins many of the examined projects.

Repurposing existing office stock avoids demolition waste and preserves embodied carbon, aligning with climate‑policy objectives. The research stresses that reuse of building fabric mitigates further land‑use expansion and supports circular‑economy principles. Energy retrofits incorporated during conversion contribute to reduced operational emissions, enhancing the overall sustainability profile of the resulting housing.

The project was executed by a multidisciplinary team comprising architects, urban planners, economists and students from HafenCity Universität Hamburg. Recommendations include: establishing clear regulatory frameworks for conversion, fostering public‑private partnerships, providing targeted financial incentives, and developing design guidelines that balance heritage preservation with modern living standards.

The study provides evidence that converting obsolete mid‑century office buildings into residential units offers a pragmatic pathway to increase inner‑city housing supply, reduce urban sprawl and achieve climate‑friendly outcomes. By leveraging existing building stock, municipalities can address housing shortages while advancing sustainable development goals.