Everyone should see three large trees from his or her home. 30 percent of your neighborhood or neighborhood should be shaded by trees. And there must be public greenery within a 300-metre walk of your house. The 3-30-300 rule of professor and urban greening expert Cecil Konijnendijk is as simple as it is ingenious. No wonder the Dutch are conquering the world with it. The aim is to make our cities more livable and to make them more robust against heat, flooding and extreme weather. Flanders is also changing tack. The Flemish government uses the idea in its Climate Health Plan, cities such as Kortrijk and Beringen are already working with it and Groen included it in his election manifesto (surprisingly: the Dutch BoerCurger Movement already did this for the party).
Breekijzer vzw, the Ghent Environmental Front and Natuurpunt brought Konijnendijk to Ghent on Thursday evening for a lecture. To this end, they went with him and a group of interested people to the Ekkergem district of Ghent, for a walk along the ‘blue-green pearls’ that were created by a neighborhood committee. “Between tree and deed, there are laws in the way and practical objections,” Anton Christiaens van Breekijzer describes the purpose of the walk: to learn in practice how the dream of healthier, cooler and greener cities can be realized.
Neighborhood volunteers Jean-François Van den Abeele and Filip Bogaert lead us to the first stop, a small parking lot next to ‘het Boerenkot’, officially the Faculty of Bioscience Engineering (UGent), where two large plane trees bravely resist the gray domination. Along the way, Konijnendijk explains that his 3-30-300 rule took shape during the corona lockdowns. “I was living in Barcelona at the time. Being able to see some big trees from my apartment helped me during that difficult time. At that time I already knew the scientific evidence for the major health benefits of 30 percent foliage and the proximity of greenery: people sleep better, have fewer heart problems and take fewer pills for mental problems.”
The three visible trees were an intuitive addition, for a trinity with great marketing value. Gradually, evidence for this followed, as last month, when another study proved that three or more trees in your field of vision are good for mental well-being. There is still work to be done at the first stop. “There is certainly room for a third tree,” says Konijnendijk, pointing to the parking spaces around it. “Don’t park those cars perpendicular but diagonally to the sidewalk, and you create a lot of space. Without eliminating a parking space, I know how sensitive that is.”
The practical objections come from an employee of the City of Ghent. “There are many reasons to plant a tree, but unfortunately just as many reasons not to. For example, the fire brigade must be able to get through here, as should the long trucks that supply the nearby prison. And you always have to share the land with utilities, soon the heating network.”
Konijnendijk smiles. “I understand the complexity. But here you fall into the classic fallacy, because trees and greenery are still not seen for what they are: basic infrastructure. Just like good roads, water pipes and sewerage. Without robust greenery, our cities will become unliveable.” Neighborhood volunteer Herman Vande Putte digs deeper: “There are new plans for the prison. It would be logical to place the loading and unloading quay on the Nieuwe Wandelen, an easily accessible two-lane road, instead of in the direction of the residential area.” Konijnendijk nods: “Sometimes the solutions are really obvious. Every new infrastructure work is an opportunity: cluster cables, organize parking spaces more logically.”
Stop two is the playground of a neighborhood school for special education. Volunteer Van den Abeele explains enthusiastically how they have softened and greened the playground, together with the schoolchildren. “Wooden play equipment, a willow tunnel and five trees were replaced by the tiles. Trees of the first order, which Cecil has in mind in his first line: with a crown area of more than 30 square meters.” Rainwater from the roof can seep under the play equipment, climbing structures have been strung over which cooling climbing plants will grow. Local residents note that the children are much calmer on the playground, says volunteer Bogaert.
Konijnendijk adds that local residents will also get more peace and quiet: softening and greening will dampen the noise. “This makes me very happy. The benefits for the students are enormous. Studies show that students learn 50 to 60 percent better in a green environment, there is less bullying, and playing in the dirt is good for immunity.” There is only one problem, Bogaert notes with a laugh: “The teachers no longer let the children in after playtime.”
A 34-metre-long facade garden was laid out against the school facade in February. There is a simple but efficient infiltration system in the ground, says Van den Abeele. “The buried infiltration pipe swallows the water from the rain pipes. We can shut down the system during heavy rainfall, causing the water to go directly into the sewer. Although it rained almost continuously, we didn’t have to do that once. Just imagine how much water we saved this way.”
In this street it is striking how many facade gardens the district has. Van den Abeele smiles. “You always hear about increasing support. This is where the ever-increasing demand comes into play: there is a demand for more greenery here, because people feel what it does for them.”
When we walk through the Groenevallei Park, the park that softens the sad appearance of the Nieuwe Wandelen prison opposite, the question arises: how do you get politicians and the public on board with this change? Clear, catchy objectives such as the 3-30-300 rule help. But a lot of money is also needed. The solution, it is unanimous, lies in focusing on the most tangible and urgent motive for greening: it is necessary for our health.
Doctor Hadewich Vanneste, who works in a general practice in the area, knows this better than anyone. “Many people know that nature is good for stress, but they do not realize enough how a lack of nature can promote fatal diseases. Heart attacks, pneumonia, asthma flare-ups, strokes…all are triggered or exacerbated by air pollution. People die from that, right? And they are driving up costs for our healthcare.” A study by the Dutch Ministry of Economic Affairs showed that 10 percent more greenery in a residential environment can save 400 million euros on the costs of care and absenteeism due to illness.
Vanneste, together with the Ghent Environmental Front, launched a petition asking the Ghent city council to implement the 3-30-300 rule. “We, doctors, are trained to focus very hard on the individual: don’t smoke, eat little sugar and fat, exercise… All correct, but I often think: with more greenery in the city, that sweet can be put on the couch in the evening. perhaps less evil.” Laure De Vroey (Bos+) uses Excel sheets: “Mutualities have known for a long time that they have lower costs for residents in greener neighborhoods. They are already investing a lot of money in prevention campaigns, why not also in greening projects?”
“Planlust”
The end point of the walk is a young construction project with a pleasant courtyard in the making. We reach it along the Pieter Colpaertsteeg, where the greening of the Ekkergem district began. The many facade gardens and greenery that connect the facades are a feast for the eyes. Local residents from gray streets who cycle or walk to school or work on hot days should feel the difference.
Van den Abeele has another pun in store as the bouncer. “Governments impose on project developers to also provide publicly accessible greenery. That is called scornfully ‘plan burden’. Well, when you see this beautiful courtyard, you will understand why I prefer to talk about ‘plan lust’. This garden is cool, all residents look out on trees and beautiful lawns with blooming flowers. And in the Buurtschuur we meet with the residents.”
Yet residents here also complained that it became too hot indoors in recent summers. And so they asked for ten extra trees, says Van den Abeele. “The city has declared our request admissible, we hope it will happen.” The residents here are fortunate to live next to the ‘Woodpecker Forest’, formed by dozens of majestic trees in a large, adjacent private garden. A doctoral student of Professor of Forest Ecology and Management Kris Verheyen (UGent) investigated the impact of the grove on the neighborhood. Together with local residents, they measured the perceived temperature at seventeen locations in the neighborhood in 2022.
While the group enjoys apple juice and cake in the Buurtschuur, Verheyen explains that the locations, which are largely unpaved and shaded by trees, have never experienced extreme heat stress. “And while on many summer days in 2022 it became warmer than 35 degrees, so-called risky temperatures. In contrast, locations that were intensely and lightly paved had twelve and five days of extreme heat stress.”
In this study, trees could make an average difference of 5 degrees, with peaks of up to 13 degrees. During hot periods, the temperature did not drop significantly at night, says Professor Verheyen. “It underlines the need for 30 percent coverage in the entire district and city.”
Every percent counts
Ghent still has a lot of work to do, according to research published last week in which the Ghent Environmental Front tested the city against Konijnendijk’s 3-30-300 rule. 33 percent of Ghent buildings have a view of three trees. The average tree canopy cover is 15 percent and 41 percent of all Ghent buildings are within 300 meters or less walking distance to a green spot. These are figures that were hotly debated after Konijnendijk’s lecture later that evening. The city council thinks the figures are too negative.
Konijnendijk calms down when we call him the next day. “I understand the defensive reaction. Bad reports can paralyze and demotivate, especially in boards that already do a lot, such as Ghent. But greening is a long-term plan. Are you only achieving 15 percent tree canopy cover today? Then work towards 20 percent within ten years, for example. The 3-30-300 rule is something you want to get to. And in the meantime, every percent of extra green already has an impact.”
