Better insights, less water

Municipalities Veldhoven and The Hague achieve significant savings with Connected Green

Founder René Voogt himself is well aware that sensors and the Connected Green platform yield many benefits in multiple ways. However, he is also pleasantly surprised by the magnitude of the savings. Michel Romeijn from the municipality of The Hague and Ron Berben from the municipality of Veldhoven share their experiences. “A saving of approximately 1,200,000 liters of water per year, we did not expect that.”

Author: Heidi Peters

Earlier this year, Stad + Groen published an article about the moisture monitoring system of Connected Green. Since then, several municipalities, including Veldhoven and The Hague, have started using it. Ron Berben, an independent green advisor hired by the municipality of Veldhoven, enjoys experimenting and conducting research. Therefore, when the municipality invested in six sensors with the accompanying software based on his recommendation, he saw an opportunity to assess the added value of Connected Green. Berben compared the costs of watering – both the water itself and the labor – for the seventy trees monitored by the sensors with the costs for trees cared for in the traditional way. Berben states, “There is a saying: measurement is knowledge. This certainly applies to moisture sensors. We often think we know a lot through experience and professional knowledge, but reality can be challenging. With current technologies, we can do much more than we realize, so we should delve into it and make more use of it.”

“We often think we know a lot through experience and professional knowledge, but reality can be challenging.”

Significant Savings

In Veldhoven, around 300 trees were knocked down due to storm damage last year. The 70 trees replanted afterward are now being cared for based on the data from the sensors. In total, 840 trees have been planted in the municipality of Veldhoven over the past year. Berben says, “The investment in the sensors and the associated subscription quickly pays off. After three months, I calculated the difference. If we had cared for all 840 trees based on the moisture sensors, we would have saved €20,000 in water, labor, and material costs in three months. I am genuinely surprised. You don’t waste water, but you also don’t give too little, so the tree is optimally cared for. And there is no need for extra trips to check the status of the tree and the soil. That is another internal saving not included in the amount. It also allows for monitoring the execution. The moisture sensors show a peak when water is given.”

From six to thirteen

Berben: ‘We started in the municipality of Veldhoven with six sensors. It was also a trial for Veldhoven, intended to convince colleagues where necessary. This indeed proved necessary, and we succeeded. Afterwards, we ordered seven more sensors. Working with sensors has an impact on your daily work. Using a soil auger to determine the condition of the ground is no longer necessary as often. There are far fewer wasted hours, and we work much more efficiently. You can remotely read the data and condition of the soil and then determine the next steps. For young trees, it is crucial to water them at the right time. Giving water too late can stress the tree. This hinders growth, causing the tree to take longer to continue growing without care. All these factors are why I am very positive about the use of Connected Green’s sensors.’

Sensors for drainage

Terraspect consulting firm, working on a project in Hendrik-Ido-Ambacht, also approached Berben for a unique situation. Construction is taking place around a pear berceau, planted in 1922. The berceau is located on a field, and now houses are being built around it. Due to its cultural-historical importance, the municipality wants to preserve the berceau. However, the construction has an impact on the groundwater level, especially here in the lower-lying west of the country. Berben: ‘Drainage has been installed so that the pear trees do not have their roots in the water. That’s nice, but for the preservation of the trees, we need to know two things: does the drainage work, and do the trees receive enough water from above? In early June, we placed eleven sensors, with a combination of one sensor at 90 cm and one at 60 cm in four locations. The sensor at 90 cm should indicate that the soil is wet, and the one at 60 cm should indicate that the soil remains moist but not wet. As long as the sensors indicate that, we know that the drainage is working. Although the sensors are easily movable, that is not the intention for these. They have a permanent monitoring function. So, you can use the sensors for something like this as well. Very convenient.’

The Hague already has sensors in planters, and in the spring of 2020, these will be supplemented with twenty sensors for trees. For the most accurate advice, the soil in which the sensors are placed should closely resemble one of the calibrated types in the app. The soil mixture for trees in The Hague differs slightly from the ten available soil types in Connected Green. Therefore, the municipality sent a soil sample to Connected Green, which was then sent to the laboratory for calibration and added to the app. Romeijn says, “We started with twenty plant and tree sensors to get an idea. What does the program do exactly, how does it work, what do the graphs say? The sensors are placed in locations with varying conditions, such as near a ditch, in the city, and on a slope where the soil is often drier. In our municipality, we have to care for 1,500 new trees annually. The results are surprising and provide clarity for the long term in some places as well. For example, you can see that trees near a ditch eventually provide enough moisture themselves. If you monitor that for a while, you can conclude that the sensor can be removed from there.”

No more fixed watering rounds

For the team that had been accustomed to the fixed watering rounds for years, it took some getting used to. Romeijn explains, “There were concerns that there would be less work for the team itself, but that’s not the case. We save on hiring and the consumption of surface water. After four months of working with Connected Green, I noticed significant savings considering the weather conditions of this season. Last year, we were driving around with five tractors; now we have an average of three, so two fewer. I attribute one of them to more efficient watering thanks to Connected Green. Additionally, I implemented a digitized water route, which allows us to drive more efficiently. That also saves one tractor. Calculate it: hiring a tractor full-time for twenty weeks costs a pretty penny. In addition, there is less diesel emissions, and we pump around 1,200,000 liters less water. We have 1,600 locations in the city where we visit for ten water rounds per year. That’s a total of 16,000 locations annually. By using sensors, we save between 50 and 100 liters per location. Taking an average saving of 75 liters per location, that amounts to approximately 1,200,000 liters less water that we pump.”

Accountability for community funds

Romeijn continues: “I also appreciate that I can use the information from the sensors to show, based on facts and evidence, how much money I have spent and how much water I have consumed and why. It’s possible that we will have a much hotter and drier summer next year, and therefore we will need more water. With this information, you can also justify the need for it in those circumstances. Furthermore, as a municipality, we want the new trees to thrive because replacing a tree that doesn’t survive due to insufficient water also incurs costs. This way of working is truly the future. We are significantly expanding the number of sensors in the coming period.”

“With this information, you can substantiate the necessity of watering.”

“Cruyffian simplicity”

“Reduced water consumption and healthier, better trees are the objectives of the dozens of municipalities that are already using our system,” says René Voogt, the founder of Connected Green. “That’s why they come to us. Measuring the conditions of green areas with sensors is not new, but it is often a very technical story. And that’s where our program sets us apart. It contains a database with information about the specific needs of the 2400 most commonly used perennial plants and trees, such as their water and light requirements and frost sensitivity. Just as one tree is not the same as another, the same applies to different types of soil. Sandy soil requires a different amount of water compared to, for example, loam or clay. That’s why we have calibrated the eleven most commonly used soil types, including soil from The Hague. The combination of the soil and the plant provides the optimal watering advice. By the way, we are sensor-independent and can connect sensors from all brands to our management system.”

Voogt concludes: “We see in our customer base where it’s dry. Municipalities in the south and east of the country are more affected by water scarcity and make more use of the app. The app displays a graph and provides a notification when it’s necessary to water. It’s truly designed with Cruyffian simplicity. More insight, fewer costs, that’s what it’s all about.”

Source: Stad+Groen