18.10.2024

“Experience tells us to keep at it”

Building design

Jana Leoni studied landscape architecture at the TU Dresden and urban design at the TU Berlin. She worked for Albert Speer + Partner, among others, before joining the City of Frankfurt. Here she spent two years as deputy head of the Urban Climate/Climate Change Department at the Frankfurt Environmental Agency before moving to the Frankfurt Climate Department when it was founded.

Climate-neutral by 2035 – the city of Frankfurt has set itself ambitious goals and established its own climate department to achieve them. It began its work in January 2023. Jana Leoni is part of the 21-strong climate department team. We spoke to the urban planner about bureaucracy in planning and asked her how well Frankfurt is positioned in terms of municipal instruments in her opinion.

The interview was conducted and published in June 2023!

Jana Leoni, At the beginning of the year, Frankfurt city councillors set a clear national example by making the greening of facades and roofs mandatory for new buildings and conversions. They also declared war on gravel gardens. A success? Or do you think more is needed?

The design statute “Open space and climate” and the accompanying information brochure are not only intended to shape building law, but also to provide assistance for climate-adapted construction. After all, just like a gravel garden, an unplanted flat roof, an unplanted façade or a treeless plot that drains into the sewer also represents a wasted opportunity for a better urban climate. And this is precisely what needs to be communicated and everyone involved in the building project needs to be aware of this. Of course, changes also need to be made to existing buildings. Here, Frankfurt is helping private applicants to make the climate-adapted design of their properties as simple and attractive as possible with the “Frankfurt Frischt auf – 50 % Klimabonus” funding program.

In the eyes of many, complex bureaucratic processes in Germany’s municipalities often make it difficult to implement innovative projects quickly. How do you see this? Do we need less bureaucracy to combat climate change and heat?

Criticism often overlooks the complexity of the requirements. In Frankfurt, however, the processes are nonetheless running smoothly. The building inspectorate is quick and efficient when it comes to project approval. If you are interested, there is also the option of climate consulting with our team, quickly and unbureaucratically. The handling of consultations and funding allocations in our funding program is also subject to a streamlined, uncomplicated procedure. The process is constantly being optimized and, according to the plan, digitalized.

The complexity of the issues applies even more to public spaces. Nevertheless, once a measure or program has proven itself, it generally works very well. For example, the drinking fountain programme, which has picked up speed after a long start-up phase and is now being implemented fountain by fountain. In the streets, there are more and more flowering islands on former traffic areas and the sponge city theme is taken into account in all new planning. So experience tells us to “keep at it”. And we in the climate department are personally committed to implementing great innovative ideas as unbureaucratically as possible.

How many technical options does the municipality of Frankfurt have to prevent the heat island effect? In other words, how well is Frankfurt positioned in terms of municipal instruments? Where do you see room for improvement?

There are already a number of existing instruments, such as the “Frankfurt Adaptation Strategy 2.0” or the “Climate-adapted urban square design” guidelines. The guideline was based on the planning for the redesign of Paul-Arnsberg-Platz, which is now the first square in Frankfurt to be redesigned in a climate-adapted way. Another one is currently being planned. As a city and together with the private sector, we can achieve a lot with tools like these.

The state of Hesse published the Hessian Heat Action Plan this February. How important is this for your work?

The Hessian Heat Action Plan shows that long-term preparation for a heat event is just as essential as concrete measures for acute heat events. In Frankfurt, the long-term measures are regulated in the adaptation strategy. A “Climate Change Action Plan” (KWAP) is dedicated to acute measures. The city wants to be comprehensively prepared for all extreme weather situations – heat, drought, storms and flooding – in order to protect people, animals, plants and infrastructure in Frankfurt.

Frankfurt am Main wants to be climate-neutral by 2035. Your department was set up in part to support this goal. In your opinion, where does Frankfurt currently stand in terms of climate neutrality? What are the biggest challenges?

Even without mentioning the current figures, one thing is certain: we still have a long way to go, which we want to achieve in a short, intensive period of time. A major, but also positive, challenge is to recognize the potential and to determine and implement the most effective measures. Solar installations on buildings and open spaces, a mobility turnaround and a turnaround in the construction and real estate sector, the use of renewable energies and waste heat are currently considered to be the most effective strategies that need to be implemented as a priority in the coming years. “Calculated climate neutrality” also includes the goal of a liveable, climate-change resilient city of Frankfurt. Our current 21-strong team, led by Hans-Georg Dannert, is looking forward to these challenges and is ready and eager to take this path together with the administration and urban society as a whole.

More on this topic in G+L 06/23.

Published as part of the international Beat the Heat initiative.

22.10.2024

Product

Architecture can do more – book review

Building design

Book

“Architecture can do more” is a beautiful, short sentence. It leaves a lot open and thus leaves room for creativity. It was written by Sabine von Fischer, a familiar name to many in the arts pages. Von Fischer belongs to the dwindling breed of architecture critics. Accordingly, this little book can also be seen as a tribute to her work, and no less a tribute to the multifaceted nature of architecture. The reason why the book often contains the sentence “Architecture can do a lot” is explained by a stroll through the pages, which are reminiscent of the feel of newsprint.

The publication from the Birkhäuser publishing house is not, as one might assume, an essay. On almost 250 pages, the handy book contains a collection of thematically grouped articles, interviews and reports. These were commissioned by newspapers, and it is precisely her many years of experience as an architecture journalist that is evident on every page, starting with the table of contents. It is immediately clear that the author has abandoned tedious conventions, for example with a spirited self-titled “declaration of love” to the architectural debate: “writing is the greatest gift that professional life could give me. […] It is an active form of participation and action right in the middle of things.” (17)

In terms of content, the 37 texts are organized around four major thematic blocks: living together under the dogmas of open space and density, politics in socially relevant architectural work, concern for the environment and climate as powerful actors, and perceptions and an aesthetic of responsibility. A concluding reflection on architectural criticism frames the content-rich contributions.

Thematic additions to this Baumeister issue can be found, for example, on page 149, when Sabine von Fischer writes critically about the high-rise buildings celebrated in the press as “vertical forests”. With all the critical journalistic practice, it seems strange that the articles are almost exclusively written with or about men. But perhaps this is just a symptomatic reflection of the media landscape, which is still a big stone in our shoe as we move forward.

“Architecture can do more!” is a call to discard restrictive thought patterns and false feelings of responsibility. The reader shows in a pleasant way how to do building practice well and unobtrusively invites us to reflect on the potential of architecture.

Sabine von Fischer’s essay “Responsibility begins with an attitude” appeared in the July issue of Baumeister architecture magazine.

06.02.2026

Resilience and sustainability

How cities are draining – techniques between decentralization and system logic

Building design

A rainy street in a city as a symbol of urban drainage and heavy rain management between decentralization and system logic. — Wet road surfaces illustrate how modern urban drainage manages water, prevents damage and ensures urban quality of life.

Rain, heavy rain, dry spells – cities face enormous challenges in the 21st century when it comes to drainage. How can an urban landscape intelligently manage water, prevent damage and at the same time create an environment worth living in? The answer lies in a fascinating field of tension between decentralized solutions, systemic infrastructure and urban innovation. Welcome to the world of modern urban drainage, where technology, ecology and urban design merge to form a new discipline.

The importance of urban drainage systems for climate resilience and quality of life in cities
Historical development and paradigm shift: from centralized sewer systems to decentralized, multifunctional solutions
Central techniques of urban drainage: urban water management, sponge city principle, blue-green infrastructure
System logic versus decentralization: conflicting goals, synergies and innovative approaches
Practical examples from Germany, Austria and Switzerland – from rainwater management to retention roofs
Technical, legal and social challenges in the transformation of urban drainage concepts
Interaction between urban planning, landscape architecture and water management
Outlook: Digital tools, monitoring and the role of data for sustainable urban drainage

Urban drainage in transition: historical foundations and new challenges

Urban drainage is not a new topic, but dates back to ancient times. Even the Romans built complex sewer systems to drain rainwater and wastewater from settlements. For centuries, sewers were seen as the ideal solution: Water had to be removed from settlements as quickly and efficiently as possible to ensure hygiene and prevent flooding. However, this logic is reaching its limits in the 21st century. Heavy rainfall events, increasing land sealing and climate change are putting traditional systems under pressure. The consequences are visible: flooded streets, overflowing cellars and stressed sewage treatment plants are now part of everyday urban life.

The cause lies less in the technology than in the paradigm. Centralized systems that rely on rapid drainage are rigid and not very adaptable. In a dynamic, dense urban structure with ever new requirements – such as quality of stay, greening and climate adaptation – new answers are needed. This is precisely where the paradigm shift begins: away from one-dimensional drainage and towards multifunctional, decentralized solutions that see water as a resource. The term “sponge city” is more than just an urban buzzword. It stands for a philosophy that retains water, allows it to evaporate, stores it and makes it usable.

But the transformation is complex. It requires a new interplay between urban water management, urban planning and landscape architecture. It is not just about pipes and canals, but about integrating retention areas, infiltration troughs, green roofs and open watercourses into the urban texture. At the same time, the requirements for control, monitoring and maintenance are increasing. Technical progress, social rethinking and political decisions go hand in hand.

The challenges are immense: How can centralized infrastructures be combined with decentralized elements? How are responsibilities regulated when private and public areas intertwine? And how can we create acceptance for visible water in a society that has relied on displacement for decades? Every answer to these questions will shape the city of the future.

One thing is certain: Drainage is no longer a purely technical field. It is a melting pot in which ecology, urban design, social issues and technology are interwoven. Only those who understand and shape this complexity can make cities truly sustainable.

Technologies between system logic and decentralization: the new repertoire of urban drainage

Modern urban drainage makes use of an impressive toolbox that goes far beyond the classic sewer network. The focus is on the balance between systemic logic – i.e. the integrated network of sewers, retention basins and wastewater treatment plants – and decentralized elements that absorb, store or evaporate water locally. The key: only the interaction of both approaches makes cities resilient to the challenges of climate change.

The core of the system logic remains the sewer network. It ensures the orderly drainage of wastewater and rainwater, protects public health and forms the backbone of urban water management. However, the load limits have been reached. Heavy rainfall events lead to hydraulic overloads, combined sewer overflows pollute rivers, and expansion is reaching its financial and spatial limits. This is where decentralized technologies come in: They relieve the overall system by retaining the water where it occurs.

The most important decentralized elements include swales, infiltration areas, retention roofs and cisterns. They temporarily store rainwater, allow it to evaporate or seep away and thus create buffer spaces in the urban water cycle. Green roofs have a dual function: they improve the microclimate, provide a habitat for biodiversity and at the same time delay runoff into the sewage system. Open water areas such as rainwater gardens or streams in the city are also playing an increasingly important role – both for water management and for the quality of life.

A prime example is the sponge city principle. It aims to keep as much rainwater as possible in the urban area and make it usable. Areas are unsealed, watercourses reactivated, more trees planted and green corridors networked. At the same time, new forms of retention are being created: multifunctional squares that serve as temporary reservoirs during heavy rainfall, or parks that become seasonal retention basins. Technology is increasingly taking a back seat – what is needed is integration into design, use and infrastructure.

Nevertheless, control remains a challenging task. Modern sensor technology, digital monitoring systems and smart control systems are becoming increasingly important. They make it possible to measure outflows, monitor storage levels and control specific measures as required. In this way, the city itself becomes a learning system that reacts flexibly to weather events. The challenge: technical excellence must be combined with planning and design intelligence.

Practical examples from Germany, Austria and Switzerland: between innovation and reality shock

What does this look like in practice? A look at current projects in Germany, Austria and Switzerland shows: The transformation of urban drainage has long been underway – but it is not without frictional losses. While some cities are implementing ambitious sponge city concepts, others are still struggling with bureaucratic hurdles or a lack of acceptance.

Berlin, for example, is setting standards with its “Climate-friendly rainwater management” program. Here, new districts are planned from the outset in such a way that rainwater does not seep into the sewage system, but is instead stored on the property. Green roofs, trough-trench systems and open water areas are standard. As a result, the city remains dry even during heavy rainfall – and gains in quality of life at the same time.

Vienna, on the other hand, is pursuing an integrative approach with its “blue-green infrastructure concept”. Here, drainage, open space design and climate adaptation are considered as a unit. The Danube Island acts as a huge retention area in the event of flooding, while infiltration basins and artificial streams in inner-city parks provide cooling. The result: a city that does not fear water, but uses it.

Zurich also relies on innovation: in the new Greencity district, all buildings have been equipped with retention roofs and cisterns. Rainwater is collected, used for irrigation or slowly released into the ground. Digital control systems ensure that the systems work optimally – and provide valuable data for urban planning. But not everything runs smoothly: legal uncertainties, questions of responsibility and conflicting objectives with other uses are slowing down implementation.

Smaller cities such as Solingen or Graz show that a lot can be achieved even with limited resources – provided there is the political will and interdisciplinary cooperation. It is crucial that drainage is no longer seen as “invisible” infrastructure, but as a designable part of urban development. Only then will solutions emerge that intelligently combine technology, ecology and use.

Challenges, synergies and future trends: where are we heading?

As promising as the new technologies are, their implementation remains a challenge. Key problem areas lie in the interface between system logic and decentralization. Who is responsible if a private green roof does not work? How are maintenance, control and financing regulated when water infrastructures are distributed among many players? And how can it be ensured that decentralized measures actually contribute to the resilience of the overall system?

The answer lies in new governance models. Cities are increasingly developing guidelines, funding programs and legal instruments to clarify responsibilities. At the same time, digital tools are being developed to facilitate monitoring and control. Urban data platforms, sensor technology and geo-information systems are becoming indispensable in order to record and meaningfully integrate the multitude of decentralized measures. The city of the future will thus become a digital, learning organism – provided that the database is correct and all stakeholders pull together.

Conflicts of use are another issue: where water is held back, it sometimes gets wet – which is not always compatible with the desired use of a square or park. Creative solutions are needed here. Multifunctional areas that serve as playgrounds in everyday life and become retention basins during heavy rainfall are prime examples of this new planning culture. The trick is to combine technology and design in such a way that synergies arise – and no acceptance problems.

The legal framework also needs to be developed further. The adaptation of building regulations, the development of standards for rainwater management and integration into urban development contracts are decisive levers. The transformation can only succeed if law, technology and planning go hand in hand.

Last but not least, the social dimension should not be underestimated. Visible water in the urban space, temporary puddles or flooded areas require a new understanding of urbanity. This calls for communication, participation and education. The urban drainage of the future is not just a question of technology, but also of acceptance and social learning.

Outlook: Digitalization, data and the future of urban drainage

Hardly any other area of urban development is currently benefiting as much from the digital transformation as urban drainage. Data-based systems, intelligent sensor technology and simulations are opening up completely new possibilities. Digital twins – realistic, dynamic city models – make it possible to simulate the effects of rain events in real time, evaluate measures and develop scenarios. The control of retention basins, the monitoring of reservoir levels or the optimization of green roof irrigation are thus becoming data-driven disciplines.

But digitalization is not an end in itself. It only unfolds its potential if it is embedded in a smart overall strategy. The aim is to make sensible use of the wealth of data without losing sight of the complexity. Interdisciplinary teams that combine urban planning, IT, water management and landscape architecture are the key to success. This is the only way to create solutions that are technically feasible, of high design quality and socially acceptable.

A central topic for the future is the linking of urban drainage with other urban infrastructures: energy, mobility, green space management and climate protection. Thinking of the city as a system means creating interfaces and utilizing synergies. Rainwater can supply energy, be used for irrigation or improve microclimates – provided that planning is forward-looking and integrative.

Finally, digitalization also offers new opportunities for participation and transparency. Visualizations, interactive maps and open data platforms make complex interrelationships understandable and invite citizens to help shape them. The urban drainage of the future is therefore not only smarter, but also more democratic – provided there is a willingness to be open.

One thing is certain: The challenges are growing, but the tools are getting better and better. Those who focus on innovative drainage concepts, digital control and integrative planning now will make cities more resilient, more liveable and ready for the climate challenges of the coming decades.

Conclusion: The city is draining – and redesigning itself

Urban drainage is undergoing radical change. Central sewer systems and decentralized green-blue infrastructures now form a new, multi-layered network of urban water management. The paradigm shift from rapid drainage to intelligent storage, use and evaporation is in full swing. This creates challenges, but above all enormous opportunities for urban planning, landscape architecture and water management.

Those who understand the technologies, legal framework and social dynamics can not only protect cities from heavy rainfall and drought, but also make them more liveable, more diverse and more resilient. Drainage is becoming the driving force behind a new urban design in which technology, ecology and urbanity go hand in hand. With digital tools, intelligent concepts and interdisciplinary collaboration, the urban water future can be shaped – sustainably, innovatively and full of possibilities.