"Cities are still being built like they were in the '50s".
On hot summer days, streets, parking lots, and other asphalted areas heat up so much that they become a health hazard. Health insurance companies report more heart diseases, circulatory problems, headaches, and unfortunately also more heat-related deaths. The German Environmental Aid (DUH) has therefore subjected 190 German cities to a "heat check" and issued a worrying report on ntv's "climate lab": "More than 50 hectares are being sealed off every day," says Federal Managing Director Barbara Metz. It's not just that green areas are still disappearing. Many cities don't even know how bad the problem is in their own backyard. "That's unacceptable," says Metz. She demands clear, legally binding guidelines from the federal government for de-sealing and suggests, among other things, moving parking lots from the city center to the outskirts to make more room for trees.
ntv.de: How big is the problem of "heat in cities"?
Barbara Metz: It's big and well-known. In Germany, we've been talking about excessive surface sealing for a long time. In our study, we issued a red card to cities with a sealing ratio of over 50 percent, a yellow card for those between 45 and 50 percent, and a green card for those below 45 percent. Even with this generous assessment, we had to hand out many yellow and red cards. Even in yellow cities, sealing has already progressed too far and must be stopped immediately because life in these cities is detrimental to health. Health insurance companies also report an increase in diseases when cities get too hot. There needs to be more green space.**
What exactly does "sealed" mean? Are they just streets?
Not quite. Sealing refers to everything that is built over. That can be streets, but also buildings and parking lots. The correct term is traffic and settlement areas. Anything where water can't seep in, usually asphalt or concrete. These surfaces heat up very strongly.**
Because the sun shines on them all day?
Exactly. For us humans, the perceived temperature is crucial, which is why it's also discussed in the weather report: When the air temperature reaches 30 degrees Celsius, an asphalt surface can heat up to over 50 degrees. This heat radiates until the evening or night. That's why cities are much hotter than meadows or forests.**
They are the opposite of sealed surfaces? Green areas like parks or even avenues feel cooler in cities?
When it's really hot, where would you rather stand? In the direct sun, under a sunshade, or under a tree? Most people would probably choose the tree. Therefore, avenues, old tree stands, and parks are crucial for our well-being in cities. We also need roof greenery, facade greenery, and green spaces that provide shade.**
Most sealed surfaces have been created because there was a need. People drive to work by car, people need a residential building to live in. Especially in cities like Berlin, there is a great housing shortage, rents are rising. Now de-sealing surfaces, that doesn't work, does it?
Yes, we live in a built environment. Especially in the 1950s and 1960s, when Germany was being rebuilt, there was no awareness of this issue. Sometimes, this is still the case today. We act as if we have endless space. However, affordable housing can also be created in existing buildings. Studies show this potential. We are not demanding that no more buildings should be constructed. But one can build less, space-efficiently, and consider where: Should I build into a floodplain where animals live, where there is shrubbery and plenty of green, or on an area that is not as highly valued for nature conservation or even wasteland? And then, one must de-seal elsewhere. Schoolyards are a great example: There are 32,000 schools in Germany, and many schoolyards are completely paved. These areas can be greened. This would be a win-win situation, also for the children.
"De-sealing" also means streets and parking lots.
If a street is not needed, it should be dismantled. This cannot be answered in general terms. Each city must look at its own situation. If it finds that de-sealing is necessary, it must decide where green can be brought in sensibly. This can be roofs, facades, or schoolyards. Fewer parking spaces are also a good idea to reduce individual traffic and the number of parked cars. Especially in cities like Berlin, there are many parking opportunities directly in front of residential buildings. Why not offer parking spaces outside the cities instead? Supermarket parking lots can also be partially dismantled.
Many car drivers in Berlin are already complaining that they can't find a parking spot. If you reduce the number of parking spaces, you will trigger a new wave of protests.
It may disturb some people, but many vehicles are moved little and block parking spaces. These cars can be parked outside and free up space for people who rely on cars. This development is needed, but of course not without the appropriate offer. You can't just take away the parking space from people. But I am sure that many people in their daily lives would appreciate fewer cars and a bit more green in front of their own door. This is also shown by our heat check: The interest is huge, the topic moves people because they realize how unpleasant the situation in the cities has become.**
You mentioned heat, which is harmful to health. Especially when a city heats up over several days. Has this been investigated?
I don't have any specific numbers, but we work with health insurance companies. They find that heart diseases, circulatory disorders, headaches, and mental illnesses increase significantly on hot days - and of course, the number of heat-related deaths also increases. Therefore, health insurance companies are also in favor of de-sealing. Green oases in the city where one can sit in the shade reduce health costs. Especially for the elderly or for families with small children who are not as mobile or can't drive to the countryside.
In your study, you also looked at the green volume of cities. How do you define a "green oasis"?
The green volume is the cubic meter per square meter: How much green is on a square meter of space. Two cubic meters of green per square meter get a red card, between two and four a yellow card, and everything over four a green card.
Lawn areas score poorly, although they are green.
Yes, indeed. They are still registered as green spaces, but of course, a tree with a large volume and plenty of leaf greenery is a better shade provider than artificial turf.
84 out of 190 cities have received a green card. Is that a good or a bad result?
Good because it means that not everything is sealed off. That would be worrying. There are cities with enough green space. However, the ranking shows that we need to redirect because more than 50 hectares are still being sealed per day. That's too much. Politics has also recognized this: By 2030, the sealing rate is to be reduced to 30 hectares per day. By 2050, the federal government wants to achieve net zero. However, this trend is not reflected in the current figures. How can this goal be achieved without measures? And why so late? How many areas will still be sealed by then? One must consider that it costs money to later re-seal these areas; it costs money to pay for the health consequences. Cities that have received a red or yellow card from us must immediately stop sealing and begin to re-seal.
Detmold, Ratingen, Potsdam, and Jena are at the forefront. What do you deduce from that? Is appropriate policy being pursued there? Are the people demanding green spaces?
It cannot be attributed to parties. There are good and bad examples everywhere. People can also do little in many places. Citizens' initiatives can oppose the construction of something, but not against land sealing. There is no legally binding basis. That is our criticism: Cities must also know what and how much they are allowed to seal. We were even surprised, but there were many letters from cities and communities saying that they finally know where they stand. That's absurd. These data must be collected and made available. Urban planners need an orientation on what they need to pay attention to.
Didn't you say that politics has already recognized the issue?
The Federal Minister of Housing, Building and Urban Development published a heat protection strategy last week, which also states: We need more green in our cities. There is also financial support for municipalities to apply for heat protection measures. That's not wrong, but this incentive alone will not be enough. There needs to be legal binding so that it's clear in planning: So much green space must be available. If you seal here, you must de-seal elsewhere.
That works? The construction industry is already complaining now about the many regulations that have to be observed. That's why almost nothing is being built. If there are more requirements ...
That works. Our building law is completely overloaded and should definitely be revised. That's why we also advocate for simple building. However, I do not accept that bureaucracy is the argument to say that we unfortunately cannot de-seal.
Barbara Metz spoke with Christian Herrmann. The conversation was edited for better understanding and smoothed out. The complete conversation can be heard in the podcast "Climate Lab".*
Despite the housing shortage and increasing demand for parking spaces, Barbara Metz suggests moving parking lots from city centers to the outskirts to make room for more trees.
The German Environmental Aid's study shows that green areas are still disappearing in many cities, and many do not even fully understand the extent of the problem in their own surroundings.
