In contrast to its outlying neighbourhoods, Eindhoven’s city centre does not have many green areas. In recent years, the centre of Eindhoven has repeatedly been declared the warmest place in the Netherlands, with temperatures sometimes exceeding 40°C. The municipality of Eindhoven currently has a clear policy of climate adaptation and greening. The redevelopment of Clausplein (Claus Square) was a step towards a greener city centre and a better connection between the city’s green areas. This project was part of Europe’s UNaLab programme, a multi-city collaboration on nature-based climate adaptation solutions.
Located in a highly urbanised area, Clausplein was comprised entirely of hard surfaces, the only exception being a few plane trees at the edge of the square. The square’s tall residential tower and its multifunctional building ‘De Witte Dame‘ together created a wind funnel, and there is a car park under the square. This lack of greenery was not only unattractive, it exacerbated the discomfort of both hot and cold spells, made worse by climate change. Although Eindhoven’s Clausplein was intended as a residential square, it was barely used as such. Furthermore, its runoff contributed to flooding in the nearby Emmasingel.
To mitigate the heat extremes and to realise a water retention plan, greenery was added and an underground water storage facility was constructed. Clausplein was transformed to a green, sustainable place that people now enjoy being in. Donker Group was commissioned by the municipality of Eindhoven to be part of a construction team to redevelop Clausplein. In cooperation with landscapers and water specialists from the municipality, among others, a multidisciplinary project team designed and realised a square that is well utilised today. Local residents, business and property owners, and ‘Trefpunt Groen Eindhoven‘ were also involved in a sounding board group. And of course good coordination was needed with the owner of the car park.
A better microclimate, cooler, flood proof, more biodiverse and attractive
Much of the concrete and stone substrate of Clausplein was replaced by sustainable vegetation: perennials, grass and trees. Plants were selected which require little maintenance and enable greater biodiversity in the area.
The design of the square is tailoured to the wishes for the square and to the City of Eindhoven’s vision for the city centre. The added greenery improves the microclimate: it dampens noise, reduces temperature extremes and creates more biodiversity. Height variation was created to make seating areas, and new trees were planted on the hills so that their roots have enough space. In addition to the three existing trees, 15 new trees were planted. Shrubs, perennials and grass surfaces were also planted. A total of 1930 m2 of green space has been created.
Use of rainwater
A special feature of the redesigned Clausplein is the use of rainwater. Below the square, on the roof of the underlying car park, a 279 m3 water retention system has been constructed. 2100 m2 of crates with a height of 15 cm were installed. The soil pack above them varies in height from 25 to 100 cm. The substrate layer can store an additional 556 m3 of rainwater.
The collection system consists of crates that fill with rainwater. This relieves the sewerage system during heavy showers. The collected rainwater is used to water the plants on the square. The rainwater runoff from the monumental building ‘De Witte Dame‘ on Clausplein has also been disconnected from the sewerage system and connected to the water retention system.
Rainwater flows into the crates via gullies. The crate system has a natural overflow to the stormwater sewer. An entire ground layer, including substrate for the plants and trees, has been placed on top of the crates. The rainwater is transported from the crates to the substrate and plants via capillary action. In practice, this has proven to require considerable precision in execution. The overflow of the crates must be at the right height so that the crates do not become completely full. That would cause the substrate to become too wet and anaerobic fouling processes to take place. Due to the capillary action, a pump is not needed.
The municipality of Eindhoven has developed a lot of knowledge in recent years in the context of greening projects and the construction of roof gardens. It turns out that improving the soil when planting vegetation in a cover-layer garden and choosing the right substrate for trees must be done with extreme care. For example, heavy equipment should not be driven over the soil or substrate during construction. A mulch layer of crushed leaves should be applied to the soil; this limits evaporation and ensures that the soil can retain moisture better. There have been no good experiences with wood chips in Eindhoven; they appear to seal off the soil too much. The clay content of the soil is also increased to enhance capillary action. By putting all these lessons learned into practice during the construction of Clausplein, the square was already nice and green and dense within one to two years.
The trees planted at Clausplein were Scotch pine, which is also found elsewhere in Brabant. The perennials are mainly cultivars, such as lady’s mantle, catnip, various aster species and grasses.
Circular re-use of materials
For the layout of the new Clausplein, some of the old street lamps and embedded spotlights were reused, as well as some of the granite pebbles and natural stone strips, totalling some 600 m2.
Donker Groep, which created the new square, will also be responsible for its management and maintenance for the first few years.
The project is monitored within the context of the EU programme UNaLab (Urban Nature Laboratories). UNaLab uses cities as laboratories to find solutions to heat and water challenges. Together with Tampere in Finland and the Italian city of Genoa, Eindhoven is one of the three demonstration cities in this European programme. For this reason, the results in the field of climate adaptation are also measured and the knowledge gained is safeguarded. The intention is that other European cities will soon apply the knowledge gained from these UNaLab projects.
Plans for the future
The redesign of Clausplein is the start of a larger transformation. The Gender River, which previously ran open through the city centre but was later covered, will again be made visible in parts of the soon to be created Victoria Park.
€ 943,000 (incl. a 300,000 contribution from Ministerie IenW and 200,000 from the EU)
Tips and learning points
- Be careful when laying the cover layer garden to ensure a suitable soil mix for the trees and other greenery.
- When the substrate is being laid, be sure it is not compacted too much by heavy equipment.
Interview met Luuk Postmes en Tony Hengstmengel