New measurement method shows exact cooling effect per tree species: urban trees lower perceived temperature by 34.5 degrees

NEWS

POLICY & LEGAL

Heleen Kommers, Tuesday 8 July 2025

83 sec

Heat stress under the microscope: urban trees as natural air conditioners

Trees can lower the perceived temperature on a summer day by up to 34.5 degrees Celsius. This is evident from research conducted by TU Delft, which precisely documented the cooling effect of 69 common tree species. The findings provide new insights for urban green management.

A large tree in Amsterdam where children love to play

Researchers conducted measurements under various trees at the Marineterrein in Amsterdam. They found that chestnut trees provided the most cooling, thanks to their dense canopies with few 'crown gaps'. Linden trees also scored highly due to their large crown density. Plane trees, on the other hand, allowed more sunlight through and therefore offered less cooling. 'Under some trees it's really dark, and that's what makes it nice and cool,' says researcher René van der Velde of TU Delft.

Every tree counts, but some cool more than others

Dashboard visualizes cooling per tree

The researchers identified five properties that determine the level of cooling: crown density, crown gaps, leaf thickness, leaf porosity, and crown structure. Based on these, they developed an interactive dashboard that shows how much cooling trees provide per street, neighborhood, or city. The model is applicable to 80 to 90 percent of trees in Dutch cities.

Tree value in euros

The new dashboard ties in with the American i-Tree model, which maps ecosystem services such as CO2 storage and air purification. The Delft version accounts for Dutch species and conditions. This even allows a financial value to be assigned to a tree's contribution—useful when making decisions about cables, buildings, or public transport. Van der Velde: 'Trees have no voice. But they are of great value for public health and the urban living environment.'

The interactive dashboard shows how much cooling trees provide per street, neighborhood, or city, and the model is applicable to 80 to 90 percent of trees in Dutch cities

From forest to neighborhood

Insights from the study have also been used in planning for the Marineterrein, where housing is being designed around existing trees. 'Normally you put buildings in first and add trees later. We've reversed that,' says Van der Velde. According to him, cities can learn a lot from this approach, especially as space becomes increasingly scarce. 'Trees are essentially free air conditioners—and we simply can't afford to lose them.'

A financial value can even be assigned to a tree's contribution—useful when making decisions about cables, construction, or public transport

This article was originally published on July 3, 2025, on the Boomzorg website.

Technische Universiteit D...

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