JUSTNature series: Episode #2 - Leuven
with Nele Janssen – 17.07.2025
This episode is the second in our exciting partnership with the JUSTNature project, an EU-funded initiative promoting greener, fairer, low-carbon cities by using Nature-based Solutions in urban planning. Today we are joined by Nele Janssen, who shares how the temporary but bold transformation of Constantin Meunierstraat – a grey, car-dominated street – into a climate-resilient space became a learning ground for just and collaborative urban design.
In recent years, the Flemish city of Leuven, Belgium, has adopted a Climate City Contract, committing to fast-track their efforts to become climate neutral well in advance of 2050. But Nele Janssen explains, Leuven has a long history of “taking climate into account in our city policies”, and so it was a natural fit for them to join the JUSTNature project and test out Nature-based Solutions (NbS).
Stationed in the Public Works department of Leuven’s city administration, Nele took on the role of local project coordinator for JUSTNature, where she supports the implementation of NbS in a social and environmentally just way. For its part in the project, Leuven acts as a city practice lab, testing concepts in two locations: Leuven Central Prison and the topic for this podcast, the Constantin Meunierstraat.
Why Constantin Meunierstraat?
The chance for Leuven to join JUSTNature came along at a time when the city was planning to redevelop Constantin Meunierstraat. Having identified the road and underlying sewage system as being in need of repair anyway, it was designated as an optimum space to be reimagined with greenery, community input, and climate resilience in mind. And it would be just one pilot project in the city, testing various ideas as part of a “climate cluster” neighbourhood.
This residential street is a wide and heavily car-oriented street – sealed and grey with parking spaces everywhere and “really no green whatsoever”, Nele explains. The abundance of asphalt was designed to channel rainwater down to the sewers and out to rivers as quickly as possible, preventing rainwater from pooling and disrupting city life. Except now local groundwater reservoirs are running low, and attempts are needed to replenish supplies.
The irony is that the street actually sees relatively low counts of vehicular traffic, making it a popular cycle route. It was clear that the design could become more inclusive to other road users.
Realisation of Leuven’s Ambition
The question was, how? Well, Nele tells us, they first had to define their objectives.
“The problem you want to solve is to make room not only for shade, and to capture water, but also room for people to meet each other, to have a chat on a little bench”, where they can enjoy “the beautiful heritage in the area”. This would be “a very, very big change for people who live there,” she adds.
To get an idea of what this could look like, Leuven asked the people who use the road every day. Workshops were used first to introduce the idea of change – and why it was necessary – and then to determine what solutions would meet the city’s and people’s requirements.
“We asked them, ‘What do you like about your street today? What you don’t like? And also, if we can change it in the future, what dreams do you have? And also, what are you afraid of?’”
These early workshops created a sense of ownership and laid the foundation for community trust.
Testing the First Concept
A designer led the co-creation process with local stakeholders, exploring variables such as where features would be built, impacts of reducing parking spaces, where benches could be placed, and of course installing greenery.
The initial installation was erected – using old building materials salvaged from other projects – in one part of the street, which is 400m in total; keeping it contained prioritised quality over scale, ideal for testing the ideas. For this reason, it was still only a temporary measure, built on top of the asphalt. Permanent infrastructure was due to follow after the testing phase to allow for changes to be made based on feedback.
“We really wanted to make something beautiful with quite big trees in it, with plants in it, with grass where you could sit on with a small pavilion with benches so they [local people] could imagine how different their street could be.” The final design even closed one lane of traffic, making room for greenery and active travel.
Evaluation & Scaling
Residents had trouble grasping that the pilot was only temporary, and that it could still change, so Nele had to explain this again. Misunderstanding or not, after three months the city collected stakeholder feedback, which was highly positive. It also evaluated the impact on traffic in nearby roads: “We saw that in fact, there wasn’t a problem.”
Reviewed, renewed, and rebuilt, the second iteration was three times the size of the original. But this created a new issue: “We couldn’t make the same quality [of] greening because it would be too intensive for maintenance. We couldn’t make them as beautiful as the first part because it was just too much work.”
That may be the case for the test phase, but not the final design. Work will start in 2026 to renovate the entire street where one-quarter of the space will be green. It will feature a traffic filter and one-way access to traffic, much of the car parking will be removed, and 40% of the street will be de-paved and replaced with a permeable surface to manage stormwater.
Advice for Other Cities
As a testing city, it’s really Leuven’s experience from this process that offers valuable lessons to other cities.
1. How Interdepartmental Collaboration Shaped the Tender
Nele says that it all hinges on finding a good designer – one who really gets what you’re trying to do. That pivots on two factors:
- Having a decent tendering process
- Bringing city departments together to be clear in your objectives.
As project coordinator, Nele brought together the perspectives from each relevant department, including public works, cultural heritage, training, mobility, etc, to ensure that they were on board to provide advice which fed into the design. Working together benefited everyone’s interests.
As the project progresses, she advises, it’s worthwhile to have regular followup meetings to keep them updated – but only as frequently as is necessary.
2. Involving All Stakeholders
JUSTNature is a co-creative project. To get the best out of the process, Leuven wanted to include as many people who used the street as possible, although “we still saw that we didn’t reach everyone,” Nele admits. Students and those who do not speak the local language were especially hard to engage.
In attempts to reach and appeal to as many people as possible, the project:
- Hosted on-location workshops, highly accessible for people who live nearby
- Kept sessions short
- Ran games for children during the workshops, so parents could fully participate without supervising them
- Sent out paper invitations to include less tech-savvy residents
- Encouraged digital and analogue feedback by distributing postcards with a QR code or which could be filled in and dropped into a purpose-built postbox on Constantin Meunierstraat.
3. Inclusive Streets Make Use of Local Knowledge
Leuven made use of its advisory boards to consult on nature and biodiversity, accessibility, and cultural heritage in a local context. These are generally voluntary groups but experts in their field and happy to be involved.
“Especially interesting is the one on accessibility,” Nele says. People with diverse accessibility needs – from wheelchair users to autism to those with visual or hearing impairments – were asked to provide their perspective on access in the public domain. In a project claiming to be “just”, it would miss the mark not to include the voices of those with diverse needs and represent them in the new street design. “Their input is just so valuable to make a very good plan.”
Next Steps
The important lessons learned in the Constantin Meunierstraat practice lab will inspire further initiatives on the same street, elsewhere in the city, other states of Belgium, and JUSTNature’s partner cities too. “For instance, when we choose a certain type of material or a certain type of species or planting procedure.”
On reflection, Nele is certain that, had the city chosen a top-down approach to transforming the street, there would have been a lot more resistance to the final design. The time and energy it took was worth it.
In April 2025, the team presented the final design – that which will be implemented permanently – to the residents. “And at the end there was an applause,” Nele recalls. “We were all amazed, we never get applause for anything! We really felt that there was a very big mind switch… So that’s a real success in my opinion.”. And a sign that trust, transparency, and co-creation are more than words here, they really delivered.
The JUSTNature project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 101003757.
Host and co-writer: Fanny Téoule
Guest: Nele Janssen
Audio editor and writer: Karl Dickinson
Music composer: Jenny Nedosekina
Graphic designer: Julia Micklewright
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