"Mehr Hecken und nicht zu eng stehende Bäume” – Windkanalversuche am Karlsruher Institut für Technologie zur Wirkung von Vegetation auf die urbane Luftqualität - Campus-Report am 23.07.2024

They are considered the green lungs of the city. Street trees are cool islands in inner cities that are heating up due to climate change. By evaporating through their leaves, they lower the ambient temperature. Their canopy of leaves provides shade in the summer heat. But trees do not always and under all circumstances improve the urban climate. They can also be the reason why pollutants from traffic cannot be properly removed from street canyons. This is the surprising result of simulations in the wind tunnel at the Karlsruhe Institute of Technology. Another surprise: hedges in busy streets are better for air quality than closely spaced trees.