01.02.2026

Green infrastructure for heavy rain – a comparison of solutions

Building design

Green urban landscape shows solutions for urban water management and climate adaptation.

Green infrastructure for heavy rain? What was once considered nice “green stuff” at the side of the road is now becoming a high-performance system in urban water management. Climate change is making heavy rainfall the new normal – and the question of which solutions really work is the most burning issue for planners, landscape architects and local authorities. Which systems protect the city, which are just a placebo? A comparison that dares to put them to the test.

Definition and significance of green infrastructure in the context of heavy rainfall events
Analysis of classic versus innovative solutions: Swales, retention roofs, sponge city, infiltration areas and more
Detailed consideration of the functionality, advantages and disadvantages of different systems
Evaluation of effectiveness based on practical examples from German-speaking countries
Legal, planning and social framework conditions
Synergies between green infrastructure, biodiversity and urban quality of life
Risks, challenges and limits of implementation
Outlook: Urban development, climate adaptation and the role of interdisciplinary cooperation
Conclusion: Which solution really scores and what remains to be done?

Green infrastructure: New heroes in the fight against heavy rainfall

Anyone strolling through German cities today will encounter them everywhere – the new heroes of water management. Green infrastructure sounds like parks and trees, but is actually much more than that: it refers to all natural, vegetation-based systems that absorb, store, evaporate or allow rainwater to seep away. In the age of climate change, they are becoming key technologies, as heavy rainfall is no longer a rare extreme, but an everyday meteorological occurrence. The consequences: Flooded cellars, overflowing streets, destroyed infrastructure. Traditional sewer systems quickly reach the limits of their capacity. The answer to urban planning: the sponge principle.

The sponge city concept – as simple as it is ingenious: cities must not only drain water away, but above all be able to absorb and retain it. Rainwater troughs, retention roofs, green areas, permeable surfaces and urban wetlands play the main roles here. They form a decentralized network that buffers rainfall and slowly releases it again. The highlight: these systems work with nature, not against it. They improve the microclimate, promote biodiversity and increase the quality of life in the neighborhood.

But green infrastructure is not a panacea. Its effectiveness depends on location, planning and maintenance, legal requirements and financial resources. While many local authorities are focusing on smart pilot projects, comprehensive implementation often remains piecemeal. If you want to know which solutions really work, you have to dig deeper – literally and figuratively.

Today, planners are faced with the challenge of finding the right systems for the respective urban structure. While space is at a premium in urban centers, suburbs and new development areas offer more scope for large-scale measures. It is not only technical performance that counts here, but also acceptance and maintenance by the population. There are also issues of financing, long-term maintenance and integration into existing infrastructure networks.

The good news is that green infrastructure is not a pipe dream. It is already being used successfully – from the cool avenue in Vienna to the multifunctional retention park in Hamburg. But which systems are really resilient, and which are more marketing than substance? Time for a critical, practical comparison.

A comparison of classic and innovative solutions: swales, roofs, sponges & co.

Let’s start with the classic: the rainwater trough. These slightly recessed green areas absorb large quantities of water during heavy rainfall, store it temporarily and then slowly release it into the ground. Their advantage is their simplicity – they require little technology, are inexpensive and can be integrated almost anywhere. However, swales quickly reach their limits: They are often overwhelmed during extreme events, and they also require space, which is in short supply in city centers.

Retention roofs are the answer to the urban lack of space. They transform roof surfaces into temporary water reservoirs. Special substrates and drainage layers retain rainwater and release it with a time delay. This relieves the strain on drains and cools the building. However, the following also applies here: the load-bearing capacity of old roofs is limited, installation is complex and maintenance is demanding. And: the storage effect is finite – in continuous rain, the roof quickly becomes a bathtub.

Infiltration-capable coverings, such as grass pavers or special paving, allow rainwater to seep directly into the ground. They are standard in new development areas, but rare in old towns – retrofitting is too complex and the ground conditions are often too unclear. What’s more, infiltration only works to a limited extent in compacted or contaminated soils.

The sponge city principle is a real game changer: here, the entire city is conceived as a water reservoir. Large parks, urban wetlands, planted ditches and open water areas form a network that absorbs, filters and slowly releases water. This system has been used successfully in Copenhagen, for example, where the city center remains dry even after a century of rain. However, implementation is challenging: it requires space, long-term planning and a willingness to completely rethink urban design.

Innovative systems such as green façades, tree infiltration systems and urban rainwater gardens complete the portfolio. They provide additional evaporation surfaces, cool the environment and create habitats for insects and birds. However, they are not a sure-fire success either: without care and irrigation, they risk drying out and can even cause damage if not implemented correctly. Choosing the right solution is therefore always a question of local conditions and the willingness to take care and maintenance seriously.

Practical examples: What really works – and where are the limits?

A look at practical examples shows that there is no one-size-fits-all solution, only tailor-made strategies. In Hamburg, for example, entire districts have been rebuilt according to the sponge city principle. Retention areas, wide ditches and green roofs ensure that heavy rainfall is almost completely held back on site. The result: less flooding, better air quality and a higher quality of life. But even here there are limits: When it rains exceptionally heavily, even the most modern systems reach their limits, cellars fill up and streets are flooded. The lesson: green infrastructure can do a lot, but not everything.

Vienna relies on a combination of retention roofs, rainwater gardens and open watercourses. New districts such as Seestadt Aspern in particular show how multifunctional green infrastructure can be: It serves as a playground, recreational space and water reservoir at the same time. But here too, maintenance is crucial – unkempt areas quickly tip over, become breeding grounds for mosquitoes or lose their function. Regular maintenance, monitoring and public involvement are therefore essential.

Zurich is taking a different approach, relying on digital control. Sensors in troughs and basins monitor water levels in real time and automatic valves control the discharge. The result is a high level of reliability – but also a high level of technical complexity. The costs are considerable and maintenance is complex. Nevertheless, the example shows that the combination of green and gray infrastructure, i.e. natural and technical elements, offers the greatest resilience.

Smaller cities are also getting in on the act: In Freiburg, for example, open ditches, swales and infiltration areas are integrated as standard in new development areas. Acceptance among residents is high and the areas are used and appreciated as green spaces. The challenge: retrofitting in existing buildings is difficult, land is scarce and ownership structures are complex. This calls for innovative, flexible solutions – and staying power.

What all examples have in common: Green infrastructure works best as a network, not as individual measures. Real resilience can only be created when swales, roofs, infiltration areas and parks are intelligently linked. Cooperation between all stakeholders is crucial – from administration to planning to the population. Without communication and care, any solution, no matter how beautiful, will remain piecemeal.

Legal, planning and social framework conditions

Green infrastructure always sounds like a free play of forces, but in reality it is a complex web of regulations, responsibilities and interests. In Germany, the Water Resources Act regulates the infiltration and retention of rainwater – and prescribes decentralized rainwater management in many places. However, implementation is often tough: local authorities, property owners and utilities struggle for space, costs and responsibilities. What’s more, funding is usually project-related, subsidies are scarce and often tied to strict requirements.

Planners have to fight their way through a jungle of standards, statutes and funding programs. DIN 1986-100 regulates the dimensioning of drainage systems, DIN 18035 the design of green spaces. However, many specifications are tailored to classic systems and take insufficient account of innovative solutions. If you want to experiment, you need courage, persuasiveness – and sometimes patience.

There is a high level of social acceptance of green infrastructure – as long as it is visible and usable. Parks, roof gardens and green spaces meet with approval. It is more difficult with invisible systems such as soakaways or underground trenches – here there is often a lack of understanding of the benefits and maintenance requirements. Education, participation and transparency are therefore key success factors.

Another topic: maintenance. Green infrastructure is labor-intensive and requires regular monitoring, pruning and cleaning. Many local authorities underestimate the effort involved – resulting in overgrown facilities, blocked troughs and non-functioning systems. Without long-term maintenance concepts, there is a risk of loss of function and therefore also of acceptance.

Last but not least: climate change is increasing the demands on planning. Rainfall is becoming more intense, dry periods longer. Systems must become more flexible, robust and multifunctional. This calls for new planning approaches, interdisciplinary cooperation and a willingness to see mistakes as learning opportunities. Only in this way will green infrastructure remain an effective means of combating heavy rainfall in the future.

Added value, synergies and limits: What can green infrastructure really achieve?

Anyone who sees green infrastructure only as flood protection is underestimating its potential. It is a habitat, air conditioning system, meeting place and biodiversity engine all in one. Trees, water features and meadows cool on hot days, filter fine dust, promote biodiversity and increase well-being. These effects are worth their weight in gold, especially in dense neighborhoods. But the added value does not come automatically – it has to be planned, maintained and communicated.

The synergies between water management, urban climate and quality of life are enormous. Retention areas become play areas, swales become flower meadows, roofs become social meeting places. Projects such as the “Blue-Green-Streets” in Rotterdam or the “Rainwater Agencies” in Berlin show how technical flood protection can be turned into lively urban spaces. The prerequisite: interdisciplinary cooperation and the willingness to overcome traditional planning boundaries.

But there are also limits. Not every city can become a sponge city, not every neighborhood offers space for swales, ponds and parks. Building regulations, ownership structures and usage requirements limit the scope for action. And: the systems are not a miracle weapon against extreme events. When it rains for a century, the only solution is often the classic sewer system – or the abandonment of sensitive uses in the flooding area.

Another risk is the commercialization of green infrastructure. If green roofs become a compulsory program, but maintenance and control are lacking, there is a risk of pseudo-solutions – green facades that dry out after a few years, swales that degenerate into garbage dumps. This is where specialist knowledge, control and commitment are required – from planners, local authorities and users alike.

And finally: social acceptance determines success or failure. Involving citizens and users, taking their wishes and fears seriously, creates identification and a sense of responsibility. Green infrastructure is then more than just technology – it becomes part of urban life, a symbol of sustainable urban development.

Conclusion: Green infrastructure for heavy rain – what remains, what is to come?

Green infrastructure is not a panacea, but it is an indispensable component of a climate-resilient city. Its strengths lie in its decentralized nature, versatility and added value for people and nature. The best systems work in a network, combining swales, roofs, infiltration and technology to create a robust, adaptable overall strategy. The decisive factors are the quality of planning, maintenance and the willingness to learn from mistakes.

The challenges remain enormous: lack of space, legal hurdles, financing issues and the balancing act between technology and nature are a challenge for planners, local authorities and users alike. But practice shows: Where green infrastructure is taken seriously, maintained and further developed, it not only protects against heavy rainfall, but also creates liveable, attractive urban spaces.

The future lies in the combination of innovation and tradition, technical precision and natural diversity. The sponge city is not a distant dream, but an ambitious goal – achievable with courage, expertise and the will to work together. If you set the right course today, you can make the city of tomorrow not only waterproof, but also liveable. And that is more than just a trend – it is the new benchmark for sustainable urban development.

05.09.2025

Industry news

Reduce cement crusts on marble

Building design

The epitaph of Konrad Popp, left: front view. Right: right side view. Institute for Conservation and Restoration, University of Applied Arts Vienna / Sarah Moyschewitz.

The marble epitaph of Konrad Popp from the late 16th century, which was attached to the southern outer wall of the parish church of St. Leonhard in Lavanttal (Carinthia), was examined and restored at the Institute for Conservation and Restoration at the University of Applied Arts Vienna due to its endangered condition.
At the time of dismantling from the wall structure, some areas of the object exhibited severe sugar-grained decay, which in some cases was accompanied by pronounced biogenic growth. Various forms of crust were found in the central area, which were identified and reduced in further steps. One crust, which was most likely formed by cement dust, and its reduction will be the focus of the investigation. […]

The memorial consists of eight white marble blocks (H:271 cm x W:125 cm x D: 40 cm) and shows the founder Konrad Popp and his family in the central field in an adorative pose. The relief rests on an inscription cartouche that reveals demographic information about the donor and is surmounted by a triangular pediment showing the coat of arms of the Popp family. The formal language is characterized by the volutes, expressive faces and the disproportionately and exaggeratedly depicted bodies, which appear mannerist and point to the end of the Renaissance. Like the design of the front side, the back of the marble blocks is highly interesting due to its shape: the blocks are not cut straight on the back and show almost no traces of carving.
To determine the stone more precisely, samples were taken and thin sections made which were examined under a light microscope and a scanning electron microscope (SEM-EDX). The medium-grained marble (crystals up to 2 mm) shows a high dolomite content (about 65 percent), as well as a high proportion of silicate minerals (about five percent) for marble, including the accessory phlogopite (Figure 2). This can be seen macroscopically as golden-yellow platelets in the marble and, in combination with the high dolomite content, is characteristic of marble deposits in the nearby Koralpe.

The installation situation of the epitaph was analyzed in order to determine the damage mechanisms. The object was sunk into a buttress on the southern outer wall, which is why it was aligned to the east (Figure 3). The installation situation can be defined as the main cause of the damage due to a structural-physical problem in the church building and the orientation. The recent façade plaster was identified as cement plaster and can be traced back to the façade renovation of the 1970s by consulting existing archival documents. The plaster lies on a natural stone masonry, which was covered with a lime plaster. This poses a problem, as cement plasters have a low water vapor diffusion capacity and do not dissipate the soil moisture absorbed by the natural stone masonry to the outside, which leads to damage on the inside of the church wall. The problem is exacerbated by the non-functioning rainwater drainage in the area of the buttresses, which is why some of the water was drained away via the façade and, at the same time, via the epitaph. The orientation of the epitaph to the east can also be described as problematic in the context of the thermal dilatation of marble. If the marble is warmed by the morning sun within a short period of time, a large temperature difference can be reached or a freeze-thaw cycle can occur more frequently. In combination with the high and permanent availability of water and the protected areas in the relief of the object, the orientation towards the morning sun optimally fulfils the growth conditions for biogenic colonization.

The marble shows a loosened structure in the exposed areas as a result of sugary-grained decay, which has been able to progress far, particularly due to a combined effect with the biogenic growth. The biogenic growth comprises a wide range of organisms, including fungi, lichens and bacteria. In addition to the weakened areas, there are also areas compacted by crusts, which can be divided into lime sinter, gypsum and cement crusts. The cement crust is a rare phenomenon and could only be determined by sampling and analyzing the cross-sections. Macroscopically, it appeared as a hard and brittle ochre-colored crust with a “pustular” surface morphology (Figure 4). Under the scanning electron microscope, a multi-layered structure of the crust was revealed: a hydraulic lime crust was present on the marble, which was firmly bonded to the rock. The remains of a hydraulic binder were found above this, which originated from a Portland cement and were covered by a gypsum crust (Figure 5). Due to the shape of the crust, it could be ruled out that this could have reached the surface as mortar splashes when the façade plaster was applied. The stratigraphy of the crust and the affected areas indicate that the formation can be attributed to cement dust, although the church is located in a rural area. It can therefore be assumed that the cement reached the surface of the building with the wind during the renovation of the façade in the 1970s and was able to form a crust in combination with moisture.

Cleaning and exposing the surface of microbiogenic growth and the various crusts was the focus of the concept of measures in addition to securing the existing structure by strengthening and reinforcing it. The treatment of the cement crust posed a particular challenge that required an unusual approach. Initial attempts to reduce this mechanically using fine tools or lasers did not produce satisfactory results, which is why the microparticle blasting method was used. Here, too, it was found that the hardness and irregularity of the crust meant that there was a high risk of the underlying marble also being processed. Microparticle blasting is a linear process in which a uniform amount of blasting material hits the treated area at a constant pressure. On a harder surface, the process is automatically slower and less effective. Due to the irregular surface morphology, thinner areas of the crust had already been removed within a short time and the marble had already been treated, while in other areas the crust was still almost in its original layer thickness. In order to apply the process as gently as possible, it was adapted as follows. A leveling layer was created to level the crust and imitate its hardness. A test series was created in advance to test the suitability of different materials as a leveling layer. Cyclododecane, gypsum and Roman cement were included in the test series. The materials were applied evenly with a brush so that the highest points of the crust were visible on the surface and the rest was covered under the leveling layer. Cyclododecane was not convincing due to its insufficient hardness and surface adhesion. Gypsum and Roman cement proved to be good leveling layers: Both materials were easy to apply and hardened quickly. In this case, Roman cement was convincing due to its higher hardness and also due to its color, as the areas to be treated stood out more clearly from the stone surface.

In addition to the material of the leveling layer, two different types of blasting material and various combinations of pressure and quantity of blasting material were tested. Another test area was used to determine the effect of the blasting angle on the degree of invasion of the method, which was applied to a polished marble slab. A flat angle of incidence of the blasting material could enable gentler work than a steep one, which is why a flat angle was chosen as the angle of incidence.
After the adaptations had been determined by test series, the crust on the relief was covered with the leveling layer and the Roman cement was covered with damp cloths for 24 hours to harden. The blasting process could begin the next day. The process is time-consuming due to the removal of the additional material, but the results and ease of application are impressive.

The condition of the marble epitaph was characterized by sugar-grained decay, biogenic growth and various types of crust. In particular, the removal of an unusual cement crust was a challenge that was met by adapting the microparticle blasting process. The process, which has been adapted using an equalizing layer, is a gentle way of reducing hard and, in particular, uneven deposits, while at the same time allowing the blasting progress to be easily observed. The technique is easy to use, makes it easier to control the blasting progress and makes the process safer. Furthermore, it should be considered that other materials could also be suitable in addition to the use of Roman cement. Through further application and analysis or evaluation, there is the potential to perfect the technique and adapt it for other situations in order to find a broader range of applications and further dissemination.

The investigation and accompanying restoration was carried out as part of Sarah Moyschewitz’s diploma thesis “The marble epitaph of Konrad Popp from the parish church of St. Leonhard in Lavanttal. On the problems of a marble with sugar-grained decay and biogenic growth” at the Institute for Conservation and Restoration (headed by Prof. Dr. Gabriela Krist), University of Applied Arts Vienna in cooperation with the Diocese of Gurk and the Austrian Federal Monuments Office, Carinthian State Conservation Office.

It is assumed that the marble blocks could have been foundlings or blocks that had been left behind in a quarry for some time.

The investigations were carried out under the guidance of sen. Lect. Dr. Farkas Pintér at the Institute for Conservation and Restoration (headed by Prof. Dr. Gabriela Krist), University of Applied Arts Vienna.

⁴Calcite powder and micro glass beads (75-125 micrometers).

⁵The following settings were selected: Micro glass beads 75-125 micrometers, 2.5-3 bar and the emergence angle was kept as flat as possible.

24.01.2025

#AIarchitecture, #SustainableArchitecture, Architecture, Trade

BIM 4.0: How Building Information Modeling is revolutionizing the future of the construction industry

Building design

According to a study from 2022, 70% of large construction companies in Europe are already using BIM. With the introduction of BIM 4.0, which integrates IoT, artificial intelligence and blockchain, these companies can significantly increase their efficiency and sustainability. Robs | Unsplash

Building Information Modeling (BIM) 4.0 is more than just an evolution of the original BIM. While previous versions of BIM were mainly used for the visualization and planning of buildings, BIM 4.0 goes beyond this: it is a holistic solution that integrates real-time data and networks all phases of the construction process. BIM 4.0 builds on the principles of previous BIM versions, but brings IoT, cloud technologies, artificial intelligence and blockchain into the construction process to make it more transparent and efficient. […]

Fun fact: According to an EU study from 2022, 70% of large construction companies in Europe are already using BIM, and over 35% of companies plan to implement BIM 4.0 in the next five years.

IoT (Internet of Things)

IoT-enabled sensors and devices can be used to continuously monitor building elements. These sensors measure factors such as temperature, humidity, pressure and wear in real time and provide valuable data that flows directly into the BIM model. If a building element is in need of repair, the system can generate a warning and proactively suggest maintenance measures.

Artificial intelligence (AI)

AI analyzes the data collected by IoT devices and can detect patterns that escape the human eye. This enables predictive maintenance that recognizes future problems before they occur. AI also supports architects and engineers during the planning phase through simulations and design analysis, which increases the efficiency and accuracy of construction planning.

Cloud computing

Cloud-based storage means that everyone involved – from the site manager to the architect to the facility manager – has access to up-to-date data, regardless of their location. The cloud also enables the processing of huge amounts of data generated by IoT and AI and promotes collaboration between teams worldwide.

Blockchain

Blockchain ensures that all data is stored securely and cannot be changed. Transparency is essential in construction projects with numerous stakeholders, and blockchain ensures that changes can be tracked at all times. This creates trust and simplifies collaboration.

Practical example: For a large office complex in Berlin, blockchain enabled seamless collaboration between architects, engineers and site managers working simultaneously in different parts of Germany. This allowed the project to be completed without delays.

BIM 4.0 enables improved collaboration and optimized processes in all project phases. The following examples illustrate how this technology is used in practice.

Planning phase

In the planning phase, BIM 4.0 provides architects and engineers with a more precise model of the future building. This includes not only the external form, but also the internal structure and possible uses of the building. This comprehensive information can be used to carry out simulations that show, for example, how the building will react to weather conditions or how the planned materials will change over time.

Construction

On the construction site, IoT sensors enable precise monitoring of processes and materials. Data on the progress of construction work and environmental conditions is sent to the cloud in real time and is available to everyone involved. By using mobile devices, site managers and tradespeople can react quickly to problems and make any necessary adjustments.

Facility management

After completion, the digital BIM model can become the basis for facility management. This is where the “digital twin” comes into play, an exact virtual image of the building that contains all current data on the condition and use of the building. Facility managers can use this information to proactively carry out repairs and maintenance.

Practical example: A hotel in Munich used BIM 4.0 in facility management and was able to reduce energy consumption by 20% as sensors automatically responded to the actual use of the rooms and adjusted the heating and cooling system accordingly.

BIM 4.0 offers numerous advantages, but also brings some challenges.

Advantages of BIM 4.0

Cost efficiency: Early detection of errors and proactive maintenance can reduce construction costs.
Sustainability: Optimized planning and usage processes enable a more resource-efficient construction method.
Transparency and traceability: All changes are documented and can be traced by everyone involved.
Global collaboration: The cloud enables teams from different locations to work together effectively.

Challenges during implementation

High implementation costs: Switching to BIM 4.0 requires a significant investment in technology and training.
Complexity of use: BIM 4.0 is complex and requires specific knowledge, which can make familiarization time-consuming and costly.
Data security: When storing project information in the cloud, data is potentially vulnerable to cyberattacks, which is why comprehensive security measures are necessary.

Expert comment: According to a study by the European Construction Council (EBC), 60% of construction companies are willing to invest in BIM 4.0, but see data security as the biggest challenge.

BIM 4.0 promotes sustainability in the construction industry and helps to use resources efficiently.

Material savings

Detailed planning and material costing minimize the production of surplus material. Architects and engineers can use BIM 4.0 to calculate exact material requirements and avoid waste as early as the planning phase.

Energy efficiency

BIM 4.0 supports energy-efficient construction methods. Simulations can be used to design buildings in such a way that they are operated with minimal energy consumption. The system also ensures that energy is used efficiently during building operation, e.g. by automatically adjusting heating and lighting.

Optimizing the life cycle

With a digital twin, maintenance work can be planned in a targeted manner, which extends the service life of buildings. This conserves resources and reduces the ecological footprint.

Sustainable construction projects: A construction project in Amsterdam used BIM 4.0 to construct an energy-efficient office building. Optimized ventilation and intelligent lighting management enabled the building to be certified as a “green building”.

Developments in the field of BIM 4.0 will continue to accelerate. Some promising approaches could further change the construction industry.

Advanced data analysis through AI: In the near future, AI could be integrated even more deeply into construction planning by making precise predictions about building materials and their service life.
Automated construction sites: Drones and autonomous robots could increasingly take over tasks on the construction site, such as checking construction progress and transporting building materials.
Virtual collaboration on a global level: New cloud and blockchain technologies are making collaboration across national borders easier and more secure.

Innovation view: A pilot project in Japan is already experimenting with autonomous robots that assemble components and correct defects based on BIM data. Such solutions could significantly change the construction industry.

BIM 4.0 has the potential to revolutionize the construction industry. With the integration of real-time data, the use of the cloud and AI and the ability to digitally record the entire life cycle of a construction project, construction processes will become more efficient and sustainable. Companies that adopt BIM 4.0 at an early stage will increase their competitiveness and be able to create modern, resource-efficient buildings.

Final thought: BIM 4.0 is not just a technological update, but a new way of building. Those who invest today are shaping the future of architecture – and ensuring a construction method that takes equal account of the needs of people and the environment.