Transformation of Clausplein

Flooding, water shortages, and heat stress. Many large cities are facing these three major challenges. And Eindhoven is no exception, with its largely paved over and bricked up downtown. "Out with the paving, in with the green" is an excellent way to deal with this. Downtown, however, things are just a bit more complicated. Due to the parking garage under Clausplein, "just building a park" was never an option.

Donker Design came up with a clever design based on a water storage system made up of types of recycled plastic crates installed on the parking garage's roof. On top of this is a layer of intensive substrate specifically prepared for this project as a base for the vegetation. The plastic crates capture water from the surrounding area and the Witte Dame's roof. If conditions have been dry for an extended period, the local plants and trees can draw on that water supply.

The square was completely transformed with trees, shrubs, plants, and grass. These plant species, which are also common in the heathland surrounding the city, enrich the area's biodiversity. Thanks to playful hills, a lawn, and various seating areas, the square's now an attractive, relaxing place to hang out.

About Donker Groep

Donker Groep is the umbrella organization that includes Donker Groen and Donker Design. Donker Groen and Donker Design worked with the Municipality of Eindhoven on Clausplein.

Donker Design is a multidisciplinary design firm that develops green interiors and outdoor spaces. From green roofs and vertical gardens to entire parks. Donker Design is a specialist in climate-adaptive solutions, circularity, and sustainability. They are known for their progressive solutions and creative take on contemporary problems.

Donker Groen has been around for more than 60 years. They started as specialists in green landscaping and maintenance. Thanks to the collaboration with Donker Design, their range of activities has expanded to include designing green projects.

For more information, check out donkergroep.com.

About the project

Eindhoven plans to turn its city center green in the coming years. Clausplein was a fully paved square on the roof of a parking garage. Apart from a group of plane trees, no greenery could be found. The municipality worked with Donker Group to transform the square into a climate-proof downtown oasis.

This project is part of Eindhoven's participation in UNaLab, a European project to climate-proof cities. UNaLab stands for Urban Nature Laboratories. Cities designate zones as testing grounds to experiment with "nature-based" solutions to heat and water challenges. In addition to Eindhoven, the Italian city of Genoa and the Finnish city of Tampere are also participating.

UNaLab set strict requirements for the plan. For instance, the square had to become a real "living lab." Donker Design came up with a proposal to add smart sensors to the square. These sensors monitor temperature, air quality, and (anonymously) site usage. The data from these sensors allows other European cities to benefit from the knowledge acquired in Eindhoven in the near future.

In addition to the transformation of Clausplein, the UNaLab project also includes the redevelopment of the Vestdijk and the area around the Stadhuis, and the greening of the shopping streets, Stratumseind and the NRE site.

About the process

The idea

Together with the municipality, Donker Design designed a square full of sustainable greenery: plants, trees, and grass. Vegetation that is relatively low maintenance but provides a lot of biodiversity. Users were central to the design. For them, the square had to become a pleasant place to hang out. That's why the design included lots of comfortable benches, seating, and a grassy area to lie on.

The basis of this design was a water collection system consisting of plastic crates that capture excess rainwater. As a result, the sewer system has to handle less water during heavy downpours. In times of drought, the crate system supplies water to the trees and plants in the square. The challenge was calculating everything carefully because the roof of the parking garage could only withstand limited loads.

Due to its open plan, Clausplein is sometimes exposed to extreme weather conditions. For instance, because of the high buildings nearby, it can be windy, and the sun is on it for much of the day. That's why the designers chose robust, low-maintenance vegetation. To give the vegetation an extra boost, Donker Design included in the plan that Donker Groen will apply a layer of leaf mulch every year. In this way, they counteract the drying out of the substrate.

Donker Design also paid close attention to project management and stakeholder management in their proposal, as there were many other parties involved in the Clausplein redevelopment besides the municipality, including the residents of the surrounding residential buildings and the owner of the parking garage.

Implementation

Between December 2019 and May 2020, Clausplein was completely overhauled. Below the square, on the roof of the parking garage, a water retention system was constructed to collect as much as 279,000 liters of water. The soil layer on top of the system can also hold an additional 556,000 liters of water. The system has an overflow to the rainwater sewer so that the soil does not get too wet. The rainwater runoff from the Witte Dame, the large building on the square, is also connected to the water retention system.

In addition to the three existing trees, 15 new trees have been planted. These are on small mounds so that the roots have plenty of room. Donker Groep also planted shrubs, ornamental grasses, and other perennials, and a lawn was laid out. A total of 1,930 square meters of green space has been added.

Many old materials were reused to redesign the square in the most circular way possible. Several lampposts and ground spots have been reused, as have the bicycle racks, some of the granite pebbles, and natural stone pavers totaling 600 square meters.

The result

The greenery in the square improves the microclimate: it dampens noise, reduces heat stress, and increases biodiversity. Since its redesign, Clausplein has withstood several heavy rainstorms and periods of drought. During the August 2020 heat wave, the square was a lot cooler than normal. Unlike in previous years, people actually flocked to the square to cool off.

Residents of the city are very enthusiastic about the green space. In the warmer months, the square's restaurants and cafes have welcoming terraces that extend into the park. And thanks to the many benches, little hills, and grassy areas, it is always a pleasant place to rest.

In addition to Clausplein, the municipality has also made the area around the Stadhuis climate-proof as part of the European climate program UNaLab. The city is currently working hard to transform Victoriapark.