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Germany’s first “Purple Roof” installed at Schauenstein elementary school

Effective measures for better control and use of water in times of climate change are on everyone’s lips. An innovative approach to solving this problem can now be seen at Schauenstein Elementary School: Here, in cooperation between the company Browatech GmbH & Co KG and Hof University of Applied Sciences, Germany’s first so-called “Purple Roof” has been installed. This is a new type of green roof concept that significantly optimizes rainwater retention compared to conventional green roofs. The installation of the roof is embedded in a comprehensive sponge city project of the Hof University of Applied Sciences and the Competence Network Water Energy. It is the first such project at a Bavarian school. The associated digital rainwater management is to become a topic in elementary school lessons.

Joy in Schauenstein: The roof of the new school gymnasium is enriched by state-of-the-art technology for flood protection and water storage; Photo: Hof University of Applied Sciences;

The relevance of the topic of water management during heavy rainfall was last experienced by some communities in the Hof region in the summer of 2021, when a disaster situation had to be declared. It is therefore hardly surprising that those responsible are increasingly looking at innovative solutions for water storage. One such solution now adorns the roof of the Schauenstein elementary school gymnasium, making it probably one of the first ever completed sponge city construction measures at Bavarian schools.

Innovation from the Hofer Land

The measure was implemented with the help of the company Browatech from Langenbach near Geroldsgrün, which contributed a core element of the innovation. The “Tech-Drainage”, patented by Browatech and only 5 millimeters thick and ultra-light, is a high-performance drainage textile that is part of the so-called “Purple-Roof concept”, known in Europe as the “Detention-Roof”. It consists of four layers: The “Tech-Drainage” as the lowest layer is the so-called detention layer.

The “Tech-Drainage” of the company Browatech; Image: Hof University of Applied Sciences;

Its function is to buffer as much water as possible and release it only after a time delay. The aim of the concept is thus to allow the stored water to flow away only gradually, thus avoiding flooding and making previously necessary retention basins or similar unnecessary or smaller.

The fact that this technology can now be used in Schauenstein is thanks to the forward-looking thinking of architect Renee Lorenz, consulting engineer Rainer Lang and Schauenstein’s mayor Florian Schaller”

Mario Browa, Managing Director Browatech

The innovation from the Hofer Land region is produced by the Sempergreen company from the Netherlands.

Mario Browa, managing director of Browatech, uses a model to explain how the Purple Roof works; Image: Hof University of Applied Sciences;

Measures against heavy rain and dry periods

Hof University of Applied Sciences is also involved in the project: the researchers’ main task is an accompanying analysis to match prototypical features of the project with the goals of the SPORE research project currently underway at Hof University of Applied Sciences in cooperation with the Water Energy Competence Network. SPORE, which is funded by the Wilo Foundation and with the university’s own funds, is concerned with answering the question of how Upper Franconia should deal with climate change and, in particular, with the extreme weather events of heavy rain and drought, and what role digital solutions play in this.

Possible fields of action here can be individual buildings, entire neighborhoods, a locality or even an entire region. The Schauenstein elementary school is an ideal example of the smallest field of action due to the use of the green roof. Schauenstein will therefore be part of the action guide at the end of our project as a best practice.”

Prof. Günter Müller-Czygan,
Head of the Institute for Sustainable Water Systems at Hof University of Applied Sciences (inwa)
Hof University of Applied Sciences includes the new roof as a “best practice example” in its SPORE research project – Prof. Günter Müller-Czygan (3rd from right) explained the goals of the project; Image: Hof University of Applied Sciences;

Further research and development projects

Another aspect to be investigated is the influence of the green roof on the sewer system. “We want to know how much rainwater can be retained, which then does not have to be drained into the sewer. Here, the university is preparing another research proposal in which the Schauenstein example will also be studied.” Together with the municipality of Schauenstein, the university then wants to derive innovation potential for new research and development projects. In particular, this involves the question of how the necessary irrigation for all areas equipped with plants can be ensured even in longer dry periods. “For this purpose, various measuring systems are used, for example, to measure soil moisture and determine water requirements. Rainwater is collected in appropriate storage tanks and economical water extraction is calculated and carried out according to the results of the data analysis,” says Prof. Müller-Czygan.

The planting of the roof is very robust and weather-resistant. Up to 60 liters of water can be stored per square meter; Image: Hof University of Applied Sciences;

Rainwater management in elementary schools

In the SPORE project “Digital Primary School Schauenstein”, a digital control and monitoring solution of a rainwater management system for a school is also being developed for the first time and is to be realized in a child-friendly way in a further funding project so that it can be used in elementary school subject lessons.

We deliberately want to sensitize children and young people to the importance of the topic of water and are therefore very pleased that we have succeeded in establishing such innovative technology – clearly visible to all – at our school.”

Andrea Fickenscher, Headmistress

More voices on this:

This is a very innovative, but also very necessary measure that is worth imitating. On the one hand, we are working on flood protection, on the other hand, we are securing water resources for agriculture and forestry.”

Dr. Oliver Bär, District Administrator of Hof County

I am pleased that we in Schauenstein are pioneers of a simple and innovative development. Unfortunately, it is regularly shown how much damage can be caused by heavy rain, we are making a small contribution with our gymnasium roof, which has a big effect. Whoever has the chance to install such an innovative system should do so, as heavy rain events are becoming more and more frequent.”

Florian Schaller, Mayor Schauenstein


The Purple-Roof was developed by the Green Roof Specialty Products (GRSP) company in the USA, which evolved from “Sempergreen” in the Netherlands. The two companies are still closely linked. The roofs are sold through Sempergreen. The Geroldsgrün-based company Browatech is the developer and supplier of the core technology of the Purple Roof, the Drainage Leger / Drainage Textile. This extends the conventional green roof into a rainfall management tool. Rainwater infiltration is controlled in such a way that it can be calculated and discharged in a throttled manner, thus helping to prevent flooding in sealed spaces.

The cooperation between the company, the school and the university came about rather by chance: Rainer Lang, consulting engineer for the Schauenstein school renovation project, and Browatech managing director Mario Browa exchanged ideas about the innovative plans for the school’s construction project. Lang revealed here that an innovative water management system was still lacking. “We brought the Detention-Roof into play here and presented the project at Hof University of Applied Sciences. There, it was decided to include the project in the SPORE research project as a prototype for a digitalized green building project,” says Mario Browa. The roofing company Geigenmüller from Helmbrechts is responsible for the construction work.

For Rainer Lang, the “school project” is the beginning of creating a new awareness towards our livelihood in general. “For years I have had the idea that our dealings with nature, with the earth, should again be more strongly included in teaching. Water, to me, is just the entry point – maybe a focus. It’s about the earth’s resources.”

Rainer Krauß

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