The congress is jointly organized by the partners of the National Urban Development Policy – the Conference of Building Ministers of the Länder, the German Association of Cities, the German Association of Towns and Municipalities, and the Federal Ministry for Housing, Urban Development and Building. The Building & Living platform contributed with its expert forum titled “Existing buildings as an opportunity! Social and technological innovations for more affordable and sustainable living space in the neighbourhoods.” Around 140 participants attended the session, where the current results and discussions from the working groups were presented and debated.

The session opened with Ortwin Renn introducing the project. Reflecting on its goal to develop solutions for more affordable housing within existing buildings, he emphasized: “There is enormous potential for innovation in existing buildings – innovation in terms of use, extension, and conversion, but also in terms of flexibility, to create more living space for more people.”

Obstacles, challenges and initial solutions

Following this, the co-leads of the working groups outlined key challenges and possible solutions:

• Neighbourhood Level: Agnes Förster from RWTH Aachen University and co-lead of the working group “Urban and neighbourhood development” explained that solutions must always be tailored to specific neighbourhood types. Whether dense mixed-use areas, transition zones, suburban spaces, or large housing estates – each offers unique potential within the existing building stock. Affordability, in line with the project’s goals, should be understood broadly, taking into account the perspectives of tenants and investors alike, as well as externalized and future costs. Förster highlighted concrete instruments such as strengthening municipalities’ pre-emptive rights and systematically activating vacant buildings to secure land for community-oriented purposes. She also stressed the need for interdisciplinary qualifications and integrated planning concepts – for example, through structured exchanges between municipalities and housing associations. Above all, she emphasized the importance of supporting cooperation among community-oriented actors to unlock the potential of neighbourhood development.

• Building Level: Adding storeys, conversions, and adaptive reuse of existing buildings can create additional housing opportunities, summarized Stefan Winter from the Technical University of Munich, co-lead of the working group “Building materials, construction, and energy”. He presented several examples, noting that cost efficiency, as well as planning and legal certainty, are prerequisites for a true culture of conversion. The existing building stock should be explicitly reflected in planning laws – beyond federal frameworks (such as the Building Code and Land Use Ordinance), state building regulations must increasingly accommodate and facilitate construction within existing structures. Harmonization between states also plays a key role. To visualize densification potential, the group is exploring cadastral mapping solutions. Additional levers discussed included tax incentives – from general housing subsidies to specific measures like special depreciation allowances for roof conversions, extensions, and additions. The group also analysed project management in existing buildings and potential optimization strategies to reduce costs in the future.

Ortwin Renn, Stefan Winter, Agnes Förster and Stefanie Bucher at the panel discussion (from left to right)

Another highlight was the presentation of the real-world laboratory mapping by Stefanie Bucher, head of the Building & Living project office. The digital map of Germany visualizes real-world laboratories and best practices related to building and housing. It serves as a tool for professionals in municipalities and administrations at all political levels, as well as for civil society organisations and initiatives, enabling them to learn from each other and advance their own projects.

Lively exchange of experiences and big questions in the context of building and living 

The session also gave the audience an active voice. Using the interactive tool Mentimeter, participants could share their experiences. When asked about “Challenges in the housing search,” price emerged as the dominant factor – encompassing supply, availability, affordability, and location. As for features considered essential in multi-story housing, balconies clearly topped the list, followed by sound insulation and elevators, far ahead of automated ventilation systems or electric shutters.

In the concluding panel discussion, central questions around building and housing were addressed:

• Accessibility in existing buildings: While desirable, full accessibility cannot always be achieved due to structural constraints, explained Stefan Winter. However, solutions can be found through varied housing mixes and neighbourhood-level alternatives – for instance, by retrofitting ground-floor apartments where elevators cannot be installed. As Agnes Förster added, accessible housing will become increasingly necessary considering demographic change.

• Land use and ownership: Ortwin Renn pointed out that land is inherently scarce and can only be managed through densification, tax reinvestment, or usage rights. Municipalities therefore need the appropriate instruments to retain land for community-oriented housing in the long term.

• Further topics included fire safety in densification projects, pragmatic approaches for building authorities, and the role of housing cooperatives and homeowners’ associations.

A clear takeaway from the session: building within existing structures comes with challenges – but also with tremendous opportunities. To seize them, greater clarity, professional training, and practical frameworks are essential. As Prof. Agnes Förster emphasized, the social dimension must not be overlooked – social, health-related, and demographic challenges are equally significant.

The existing building stock plays a central role in creating affordable and sustainable living. The participation in Rostock demonstrated the importance of exchange and collaboration in this field. The Building & Living project team would like to sincerely thank all experts and participants for their valuable contributions.