Building & Living:
Platform for
Networking, Synthesis
and Transfer

The goal

The aim of the Building & Living platform is to identify the obstacles to existing innovations for more affordable housing and to provide key impulses for the change of the construction sector. In addition to affordability, the criteria of sustainability and quality (essential living comfort) are also considered.

The project is focusing on existing building structures in urban areas. Being discussed are solution options and impulses for reusing, adding storeys, building extensions and other types of redensification.

More about the project

Project outcomes published

acatech IMPULSES: How municipalities, the federal government and the federal states can create affordable housing within the existing housing stock

With two publications from the acatech IMPULSE series, we are publishing the key findings of our Building & Living: Platform for Networking, Synthesis and Transfer project: by setting out concrete courses of action, we are addressing the federal and state governments – as the key legislative and regulatory bodies in Germany – as well as local authorities. After all, affordable housing remains one of the greatest challenges facing Germany. The existing building stock in urban areas offers considerable potential to address this issue – for example, through adding storeys, constructing extensions, converting commercial and office space, subdividing large flats and other forms of infill development.

Publication from the project

acatech IMPULS: "More affordable housing in the existing stock – options for action for the federal and state governments”

As the key legislative and regulatory authorities, the federal and state governments establish the regulatory framework for the building sector, in particular building and planning law as well as state building regulations. Furthermore, policymakers and administrators at these levels steer housing support schemes and the training of skilled workers. This is where our publication “More affordable housing in the existing building stock – Options for action for the federal and state governments”, which was produced as part of our project, comes in. With this publication, our experts are addressing the federal and state governments.

Publication from the project

acatech IMPULS: “More affordable housing in the existing building stock – options for action for local authorities and municipal organisations”

As part of our project, around 40 experts discussed options for action to increase the supply of affordable housing in the urban building stock, prioritised them according to their impact, and developed them with specific target groups in mind. This has resulted in two publications in the acatech IMPULS series. One publication is aimed at local authorities and municipal organisations. As key players in the housing market, they face the challenge of ensuring affordability whilst also giving due consideration to environmental sustainability and a high quality of living.

Project outcomes published

acatech IMPULSES: How municipalities, the federal government and the federal states can create affordable housing within the existing housing stock

Housing sufficiency: Sustainable approaches for more affordable housing

How much living space do we actually need? How can existing housing better be distributed, adapted or shared? Particularly in high-demand urban areas, housing is scarce and expensive, and housing needs change over the course of a person´s life At the same time, space is used socially unbalanced. Overcrowding, very large homes with only a few occupants or even vacant properties, for example, make it clear that it is not just about new construction, but also better - and above all flexible - use of existing stock. Housing sufficiency solutions can help address this issue by combining ecological goals, such as reducing land consumption, with social objectives, such as increasing the availability of affordable living.

Measures to bring vacant properties back into use to increase the housing availability: examples from towns and districts

In Germany, around 1.9 million apartments were vacant according to the 2022 census – equivalent to 4.3 per cent of the housing stock., with half of them vacant for more than one year¹. While in many major cities such as Munich, Hamburg or Berlin only about 2 to 3 per cent of apartments are unused, significantly higher vacancy rates are found in eastern German regions and in some structurally weak rural districts. Many large and medium-sized cities are already implementing instruments to systematically record vacancies and reactivate unused properties. This represents a key lever for creating housing and thus making an important contribution to more affordable housing.

¹ Federal Statistical Office

© Roland Baege

Dr. Svenja Haferkamp, Head of Strategy, Sustainability and Innovation, GEBAG Duisburger Baugesellschaft mbH, on the subject of Funding

“The funding landscape for housing construction is becoming increasingly strained: resources are often oversubscribed and quickly exhausted due to rising demand, which increases competition and access barriers — particularly for actors working in the public interest. Approval authorities are gaining influence, while limited capacities slow down procedures. However, digitalisation, professionalisation, and political initiatives offer prospects for greater efficiency and relief.”
© Simona Bednarek

Prof. Dr.-Ing. Verena Brehm, Co-founder of CITYFÖRSTER architecture + urbanism and Professor at the Department of Design in an Urban Context, University of Kassel, on the subject of Sufficiency measures in the context of housing promotion

"Sufficiency measures are an effective approach to promoting affordable housing at the building and neighbourhood level. These include reactivating vacant properties, establishing communal forms of living, and promoting needs-based use through support with moving house, flat swapping or the (temporary) sharing of large flats. Sufficient forms of mobility such as car sharing, rental cargo bikes, etc. also contribute to reducing housing costs. In addition, these measures generate social added value that goes far beyond the purely quantitative provision of living space."
© Julius Gnoth

Sarah Dungs, Chairwoman of the Association for Building in Existing Contexts (Verband für Bauen im Bestand e.V.) and Managing Director of the Greyfield Group, on the topic of Consequences of legal changes for local municipalities

“Simplifying regulations is only the first step. If we want change, we must strengthen the local level – with clear framework conditions, training and genuine legal certainty for those who make decisions on a daily basis.”
© www.ingasommer.de

Jens Lütjen, Managing Partner, Robert C. Spies Gewerbe und Investment GmbH & Co. KG, on the subject of Consequences of legal changes for municipalities

"The construction industry, including municipal building authorities, needs pragmatic and stable framework conditions – this can stimulate construction activity.
It is positive development, at the political level, efforts are made to reduce complexity – for example through the Bau-Turbo, the Gebäudetyp-E or the Hamburg Standard. However, these approaches also need to be implemented within operational administrative structures. For this, those responsible require legal certainty for their decisions. Municipalities already have good instruments at their disposal, but they need to be empowered to use them more effectively as a flexible applicable toolbox."
© Huber & Sohn GmbH & Co. KG

Josef Huber, Managing Partner, Huber & Sohn GmbH & Co. KG, on the subject of Easier building in existing structures

“Regulations for existing buildings – with the aim of facilitating conversion and refurbishment – should urgently be integrated into the Model Building Code. It is essential to ensure that no other hard‑to‑meet requirements are introduced elsewhere that would once again make building in the existing stock more difficult.”
© Elisabeth Pfahler-Scharf

Petra Wurmer-Weiß, Consultant, Energy Efficiency and Sustainability Advice Center (BEN) of the Bavarian Chamber of Architects, on the subject of Sustainable densification in urban areas

"With increasing urban densification, the requirements for the quality of open spaces and for climate adaption measures are also rising. Dense building concepts therefore require addidional solutions for heat protection and cooling, as well as sufficient areas for rainwater infiltration. Green facades or roofs can at least partially compensate for higher density and contribute to sustainable urban development. Such requirements need to be anchored in law. Simply relaxing building regulations in favor of more housing without considering climatic and social impacts would be too short-sighted.
© Bertram Bölkow

Sebastian Pfeiffer, Managing Director, LESG Gesellschaft der Stadt Leipzig zur Erschließung, Entwicklung und Sanierung von Baugebieten mbH, on the topic Social binding for more affordable housing

"Successful cooperation between local authorities and private investors requires a balance between both interests and an understanding of the respective economic scope. Instruments such as urban development contracts or hereditary building rights can create the framework conditions for this. For example, an investor can commit to extending the social binding of flats. In return, the local authority eases the requirements for outdoor facilities. This balancing act requires sensitivity and should be promoted through training on both sides."
sufficient."
© Frank-Thomas Kronsbein

Frank-Thomas Kronsbein, Product Manager Residential Buildings, GOLDBECK Technologies GmbH, on the subject of Parking spaces

“Even though many people, including those in urban areas, still depend on owning a private car, future development should be enable both more individual mobility and better public transport through significantly denser, more urban forms of building. Similarly, housing construction should no longer be burdened with the costs of providing parking spaces through to parking regulations, since ‘residents’ are no longer synonymous with ‘parkers’. Some cities are already demonstrating alternative solutions, such as neighborhood car parks.”
© Josef Gangkofer

Prof. Dr. Simone Linke, Professor of Urban Planning and Landscape, Landscape Architecture Department, Weihenstephan-Triesdorf University of Applied Sciences, on the subject of Interdisciplinary qualification

“Urban planning and urban design are not the same as architecture and urban design. We need experts with a background in urban planning who know exactly which issues are relevant – such as mobility, green infrastructure, circular construction and the circular economy, economics and politics.”
© ByAK

Jutta Heinkelmann, Housing, Standards, and Regulations Officer at Bavarian Chamber of Architects, on the subject of Easier building in existing structures

“The simplified approach to building in existing structures should be incorporated into all state building codes (LBOs). Many federal states are currently seeking to include provisions that facilitate and privilege construction within existing buildings in their respective LBOs. With corresponding amendments to the Model Building Code (MBO), developments are moving in the same direction. The goal should be harmonization - that is, aligning the LBOs with regar to their regulations on existing building.”
© Julius Gnoth

Sarah Dungs, Chairwoman of the Association for Building in Existing Contexts (Verband für Bauen im Bestand e.V.) and Managing Director of the Greyfield Group, on the topic of Simple construction

“Affordability does not result from ever-changing standards, but from clarity. Simple construction requires binding minimum requirements that are ecologically reasonable, economically viable and practically feasible.”
© Frank-Thomas Kronsbein

Frank-Thomas Kronsbein, Product Manager Residential Buildings, GOLDBECK Technologies GmbH, on the subject of Urban densification

“A model for densification must be developed for society as a whole - it should be developed in a dialogue with the citizens. This way, densification construction projects can be implemented based on a shared consensus and in line with the needs of the urban population.”
© Josef Gangkofer

Prof. Dr. Simone Linke, Professor of Urban Planning and Landscape, Landscape Architecture Department, Weihenstephan-Triesdorf University of Applied Sciences, on the subject of Inter-municipal cooperation

“Cooperation between municipalities is a key factor. Many people want single-family homes, and if one municipality does not offer them, young families often move to a neighbouring municipality. When municipalities join forces, they can create more attractive housing options instead of relying primarily on new development on greenfield sites. A shared land pool could help to use land more strategically. Working together makes it easier to address these challenges, which is why inter-municipal cooperation should be strengthened.”

Facts and figures

Between 2014 and 2023, only around 11 per cent of completed construction projects nationwide were extensions and conversions to existing housing stock; the majority were therefore new-builds.

(Source: “Wohnungsbau braucht (mehr) Fläche, InWIS Berichte 37”, Bochum 2025)

Experts estimate that up to 1.7 million additional flats could be created simply by increasing the number of storeys in commercial buildings (office blocks, retail premises and car parks)

(Source: Own calculations by InWIS, based on data from the Technical University of Darmstadt/Pestel Insitute, 2019)

Completed Housing Units by Client Type in 2024
In 2024, private clients and housing companies were the largest commissioners of residential buildings, with a total of around 183,000 housing units, accounting for 84.8 percent. They were followed by commercial enterprises in the trade sector, with a share of 6.1 percent. Although public-sector clients accounted for only 4.3 percent of commissions, the number of completed dwellings—9,400 units—has increased sixfold compared to the beginning of data collection in 2001.

(Source: dena Building Report 2026, Federal Statistical Office 2025)

Example projects from our real-world laboratory mapping

Real-world laboratory:

SinBa – Social innovations for climate-neutral building and living

The SinBa project explores how social innovations can advance climate-neutral and socially equitable building and living in cities. It focuses on linking social innovations with technological and structural developments in order to align ecological, social, and economic objectives. A transdisciplinary project team from the Wuppertal Institute, inter3, and the cities of Wuppertal and Mannheim develops innovations, tests them in real-world labs, and supports selected approaches in scaling “from niche to mainstream”.Go to project website

Best Practice:

From parking garage to residential and work space:
Gröninger Hof

Gröninger Hof is an innovative cooperative project in Hamburg that demonstrates new approaches to affordable housing. The Gröninger Hof eG cooperative is transforming a former parking garage into a diverse residential and work space with cultural offerings. The plan includes 90 apartments designed for various lifestyles – from traditional households to accessible housing and cluster apartments. The project relies on community engagement and close collaboration with local stakeholders to create sustainable urban living environments.

Go to project website

Real-world laboratory:

OptiWohn – Optimizing space use

The OptiWohn research project develops innovative strategies for the optimized use of existing – both used and unused – residential spaces in urban neighbourhoods, ensuring that housing areas are used according to local demand. In pilot cities such as Cologne, Göttingen, and Tübingen, the project examines how municipal housing agencies can identify needs, provide guidance, and facilitate apartment changes, subletting, or shared living arrangements. The aim is to reduce the consumption of space and resources, activate the potential for vacant properties within the existing housing stock and develop recommendations for action for municipalities.

Go to project website

Real-world laboratory:

NaMaRes – Resource management in neighbourhoods

The NaMaRes project develops a software solution for resource-efficient urban neighbourhood planning. Its aim is to systematically capture and assess land, materials, water, and ecosystem services, thereby supporting decision-making for sustainable neighbourhood development. This includes an overview of local resources, evaluation models, and a web-based planning tool that visualizes and simulates different measures. The results are translated into practical guidance for municipal planning processes through a handbook. the initiative targets local authorities, planning offices, and decision-makers to foster the sustainable transformation of existing urban neighbourhoods. The Innenstadt-Ost district of Karlsruhe served as real-world laboratory for the project.

Go to project website

Learn more: To the mapping

Review: Existing Buildings as an Opportunity!
Building & Living at the 18th National Urban Development Policy Congress

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 discussed.

Best practice:

From administrative headquarters to senior living

Where offices once stood, life has now moved in: The former administrative building of GESOBAU AG in the Märkisches Viertel neighbourhood of Berlin-Reinickendorf has been transformed into a modern residential and commercial property – with 66 new and six existing flats, with barrier-free floor plans and space for a new neighbourhood. This provides, among other things, age-appropriate and affordable options for senior citizens, while the surrounding quarter benefits from new services. The project shows how conversion rather than new construction can bring about lasting change in urban neighbourhoods. You can find out more about the conversion of the GESOBAU administration building and other exciting examples with the potential to create affordable housing in existing buildings on our real-world laboratory mapping platform.

The project is a prime example of how rebuilding instead of new construction can sustainably strengthen urban neighbourhoods. More information on the reuse of the former GESOBAU administrative building, along with additional inspiring examples with potential for creating affordable housing within the existing building stock, can be found in our Reallabor Mapping.

Go to the mapping

Real-world laboratory:

Sonneneck – a neighbourhood for all generations

Grey prefabricated buildings in Dresden's Sonneneck neighbourhood are being transformed into bright, inviting residential buildings – with balconies, lifts and warm colours. The aim is to create affordable living space with apartments of appropriate sizes for families, couples and singles, as well as barrier-free living space for senior citizens. Playgrounds and green spaces are also being created. Some of the renovations and restructures are being carried out while the buildings are still occupied, with residents being kept informed regularly in writing and through on-site visits.

Revitalising existing buildings and their surroundings and creating a mix of affordable and liveable housing: more examples of real-world laboratories with the potential to create affordable housing in existing buildings and best practices can be found on our digital map, the real-world laboratory mapping.

Go to the mapping

Real-world lab Mapping by Bauen & Wohnen and KIT now online

How can real-world laboratories contribute to creating affordable housing in urban areas? We developed a new mapping tool with scientific support from the Karlsruhe Institute of Technology (KIT). An interactive map showcases real-world labs and selected innovative best practice examples in Germany.

To the mapping

Potential for apartment swapping in existing housing stock

Through apartment swapping, up to 11.5 million square meters of living space could be unlocked each year — equivalent to around 357,000 rooms. Sixty-five percent of all tenants would be willing to participate if a suitable offer were available.

Learn more

Loft living space potential: 429,252 additional flats…
... could be built under and on German roofs in the future - according to a study by the Berlin-based technology company Leaftech.

Infill development through extensions of existing buildings offers clear advantages over new construction

Land use, resource consumption, CO₂ emissions, and especially building costs are significantly lower. Average costs per square meter of gross floor area:
- Roof conversion: €1,797
- Extension: €1,738
- New construction: €2,765

© David Ausserhofer

“People should feel comfortable in urban areas and be able to afford an adequate quality of life. This requires the removal of unnecessary regulations and a housing policy that focuses on social equality.”

Prof. Dr. Dr. h. c. Ortwin Renn
Former Scientific Director, Research Institute for Sustainability, acatech Executive Board, Scientific Project Manager “Building & Living” platform

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© Julius Gnoth

“Building in existing structures will become the new industry standard - according to Sarah Dungs, Chairwoman of the Association for Building in Existing Contexts (Verband für Bauen im Bestand e.V.) and Managing Director of the Greyfield Group. During the webinar "Building in Existing Structures: seizing opportunities, overcoming challenges," she explained where CO₂ emissions originate in the construction industry, how resources can be conserved, and why a new mindset is essential for working with existing buildings."

Sarah Dungs
Chairwoman of the Association for Building in Existing Contexts (Verband für Bauen im Bestand e.V.) and
Managing Director of the Greyfield Group

Read the article
© Ulrich Mayer

“This is a highly relevant issue: how can we create new living space not on ‘greenfield sites’ with even more sealing of land, but by using and densifying the already built environment, sealed areas and already built infrastructure?”

Prof. Dr.-Ing. Stefan Winter 
Former Ordinarius of the Chair of Timber Structures and Building Construction, TU Munich,
Lead of working group 1 "Building materials, construction and energy“

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© Martin Braun

“We can only create a future worth living in if problems and their causes are analysed from multiple perspectives and if we take targeted measures to address current dysfunctional contexts and overcome existing obstacles. It is important to bring together knowledge from different areas: from planning, construction and operating, science and practice, experts and people in the neighbourhood.”

Prof. Dr.-Ing. Agnes Förster
Head of the Chair of Planning Theory and Urban Development, RWTH Aachen,
Lead of working group 2 "Urban and neighbourhood development“

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© Schöck Bauteile GmbH

"I am particularly passionate about the connection between sustainability and affordable housing. The Building & Living Platform offers the ideal opportunity to bring our expertise into the discussion and work together on solutions for the construction industry of tomorrow.“

Dr.-Ing. Daniela Kiefer
Structural Engineer for Bridges, Building Construction and Construction Products, SMP Ingenieure Im Bauwesen GmbH,
Lead of working group 1 "Building materials, construction and energy“

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