Climate change is also causing more and more hot summer days in Germany. Tropical nights with 20 degrees and more are becoming more frequent. What can be done to make people in inner cities easier?

More green and more shade can make the particularly high temperatures in the city centers more bearable from the point of view of the Federal Environment Agency.

“We are not completely at the mercy of the heat island effect,” said UBA President Dirk Messner. “With significantly more green, especially new trees and more shading from external sun protection as well as green roofs and facades, spending time outdoors and the temperatures in the apartments can be made much more pleasant.” The old trees in the cities must be protected and watered regularly.

Cooler temperatures thanks to trees, awnings and umbrellas

According to the information, the UBA had systematically investigated, among other things, using simulation calculations, how cooler temperatures can be achieved in inner-city districts and in the buildings there. In addition to Hamburg, Cologne and Frankfurt, the researchers also looked to Madrid and Tunis. Trees with large crowns, awnings and umbrellas would have provided positive effects in the quarters as well as in the houses and apartments. Green roofs, spraying water and bright colors for the facades also had a positive effect. The scientists report that this measure also reduced the energy requirement for cooling. In the subtropical quarters or in attic apartments in the temperate latitudes, for example, air conditioning cannot be dispensed with without sacrificing comfort.

The background to the investigations is that the temperatures in cities are higher than in the surrounding areas. Experts speak of the “urban heat island effect”. According to the UBA, it is particularly strong on summer nights. Large areas of sealed soil and a lack of green are the reason that less cooling occurs through evaporation. In addition, the buildings heat up, air cannot circulate so well and waste heat from engines also contributes to the formation of heat islands in cities.