Anyone who has ever tried to sit on the Rhine Boulevard during the day on a summer’s day knows what I mean: the concrete steps turn into unbearably hot rooms when it’s 30 degrees or more. In the evening, people still like to sit here because the concrete steps have stored the day’s warmth and radiate it away.
The new building in front of the entrance to the Deutzer Messe, where the Barmer district used to be, also looks to visitors like a concrete monster that gets unbearably hot on hot days. Many Cologne residents have also recently criticized the new Gürzenichstrasse for not having any greenery here.
These are just examples of projects in Cologne that have been built in recent decades. There are of course also large green spaces in the city, such as the green belt and the city forest.
Subscribe to newsletter ✅ Get the Cologne bedtime story as a PDF ✅
Subscribe to newsletter ✅ Get the Cologne bedtime story as a PDF ✅
Sealing: Cologne in a bad place
But how are the green spaces distributed in Cologne compared to other cities? The German Environmental Aid has carried out a so-called Heat check and assessed cities with over 50,000 inhabitants according to the degree of sealing and green volume per square meter.
Cologne is one of the worst performing cities in NRW. According to Umwelthilfe, Cologne has a sealing rate of 49.72 percent. This is higher than in all other large NRW cities. For comparison: For Düsseldorf, the rate is 44.55 percent, and cities such as Gelsenkirchen (45.29 percent) and Dortmund (42.91 percent) also perform better.
According to Umwelthilfe, the areas with the highest sealing are Hürth (53.21 percent) and Frechen (52.65 percent).
In addition to sealing, the volume of green space also played a role in the evaluation. In other words: how many cubic meters of green space are there per square meter of area (trees, green and flower strips, etc.)? Here too, Cologne, with 3.13 cubic meters, is only in the lower middle range compared to other cities.
Advertisement:
Why are sealed surfaces so relevant?
The German Environmental Aid: “A sealed surface converts the incoming radiation energy almost completely into heat. Only unsealed surfaces can absorb water and contribute to cooling their surroundings through evaporation.”
What are the demands on the cities?
According to Umwelthilfe, the task of future urban development must be to ensure urban greenery, decentralized infiltration and flood protection in the districts.
In addition to more greening and shading, older buildings also need to become more climate-resilient: “Buildings that use little energy also heat up less in summer. Green roofs and facades can keep buildings cool.”
For Cologne, too, there have long been models that analyze where and how heat islands arise in the city: Here you can read about the 6 measures that can be taken to avoid heat islands.
