The example of the municipality of Singen (Hohentwiel) demonstrates why green-blue infrastructure has such a large potential effect on the well-being of citizens: The business park, which expanded quickly from 1950 to 1970, makes up almost half of the cities’ core territory today. It was built according to the standards that were prevalent in the middle of the 20th century: the streets are very wide, adapted to trucks that need to rank and a large number of commuters coming to Singen to work from neighboring towns and villages. Permeable surfaces were avoided because oil leakages were common.
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Tobias Herbst, Municipality of Singen (Hohentwiel)
There’s no doubt: On the hand, the pilot area in Singen (Hohentwiel) is typical for a large number of business parks in Germany – and it also makes it ideal for a project like IB-Green, whose aim is to change the “grey” status quo in business parks and to promote the uptake of green-blue infrastructure in existing business parks.
In Singen, IB-Green project activities will be implemented in two different locations: at the Friedrich-Ebert-Square at the entrance of the industrial area and in the Gottfried-Daimler-Street.
The 13-meter-wide Gottfried-Daimler-Street will be receiving a “green makeover”: Approximately 500 square meters of pavement will be removed and twelve new trees will be planted. Different types of trees will be planted: four Hungarian oaks, three “Brabant” silver lindens, three “Spaethii” purple alders and two “Summit” red ashes.
The planting will follow the sponge city principle, specifically the Stockholm model. In this approach, an underground tree pit is excavated and filled with coarse gravel. This loosely compacted material provides ample space for root growth while allowing water infiltration. Deeper layers are enriched with a nutrient-rich biochar substrate. This encourages roots to grow downward rather than outward, reducing the risk of damage to the pavement.
An additional inlet directs rainwater into the tree pit during summer. This reduces the need for irrigation and enhances evaporative cooling. In winter, the inlet is closed to protect the trees from de-icing salts. These could damage roots by disrupting water uptake and causing physiological drought stress. Overall, the trees are able to absorb, store, and gradually release water, contributing to the cooling of the surroundings.
© Tobias Herbst, Municipality of Singen (Hohentwiel)
Additional activities will be implemented at the Friedrich-Ebert-Square: A public square in the vicinity of a few companies and a retailer, as well as a few restaurants that are frequented during the lunch break. However, next to the square is highly sealed area which is not actively used as a multifunctional, recreational green space. The plan is to unseal 250m², with the aim of improving rainwater infiltration and reducing heat accumulation. Further, additional trees will be planted, outdoor exercise equipment and additional seating for lunchbreaks installed. The general idea is to improve the Friedrich-Ebert-Platz to serve as a visual example and demonstrate the value of green-blue infrastructure for employees and businesses. To ensure they are onboard and can share ideas, the companies located nearby will also be involved in the development of the planning concept.
The planting of twelve threes in Gottfried-Daimler-Street has already started and should be completed by the end of March 2026. Plans for the transformation of Friedrich-Ebert-Square are currently being finalised. The city council is expected to approve them and award the contract this summer. The construction works are set to begin in the fall and be completed by the end of the year.
© Tobias Herbst, Municipality of Singen (Hohentwiel)
In addition to the implementation of green-blue on the municipalities’ grounds, Singen is also consulting companies situated in existing business parks on how they can implement green-blue infrastructure on their premises. For example, after an on-site consultation with a bigger company last year, the municipality of Singen provided them with a consultation report containing different suggestions for implementing green-blue infrastructure. The company decided to begin planting a “tiny forest” on their premises.
Contact at Municipality of Singen:
- Alena Hayer, Alena.Hayer@singen.de
- Tobias Herbst, tobias.herbst@singen.de
Link: https://www.singen.de/leben/klima+und+umwelt/klimaanpassung/interreg-projekt+ib-green