Is it a birdhouse or a hanging thermos flask? no. This summer, white gauges will go up in eight Dutch cities. Funds monitor how urban trees are doing. TU Delft can use this data to see how much cooling a tree produces for the city.

“It’s hard to grow in the city,” says Rene van der Velde, a professor at TU Delft, standing under a tree in Amsterdam with the meter in hand. “We use this to measure the temperature and humidity of the tree.”

The birch, linden, and plane tree are some of the first to be examined. Using the data, researchers can learn how the tree contributes to environmental cooling. So it’s not so much about trees’ value in terms of money, “but, for example, about carbon dioxide capture, water and particulate capture.”

“We put this data into the i-Tree, which is a computational program that shows you how this tree is doing in the city,” explains Van der Velde.

The results of the research will be shared with the city, managers, tree technical offices, architects and urban planners. “We hope they do a lot to give the trees a good home and a good environment.”

Van der Velde is also hopeful that municipalities will eventually be able to use the data to learn more precisely what trees need in the city. “The more attention we pay to these kinds of values, the more care and attention we can give to trees.”

In the end, this can also save municipalities money. “Trees cost a lot of money to maintain. If we can express their value in euros, we can allocate our budgets more intelligently,” says the Municipality of Amsterdam.

For two years, the measurements will be carried out in trees in Amsterdam, The Hague, Dordrecht, Groningen, Heerhogovard, Hendrik Edo-Ambacht, Rotterdam and Utrecht. From October, cities can start with the first results.