AI suggests greener future for German city centres

By Elan Castañares

Artificial intelligence (AI) has offered imaginative and visually striking proposals to help urban areas cope with rising temperatures.

According to Suedwestrundfunk (SWR) news, AI-generated designs for central squares in the German cities of Mainz and Stuttgart showcase greener, cooler and potentially more liveable futures, but experts are cautious about the feasibility of these visions.

AI envisions greener public squares

The experiment, carried out by SWR Aktuell, involved feeding photographs of Gutenbergplatz in Mainz and Marktplatz in Stuttgart into an AI system, accompanied by a simple prompt: “Please plant trees, green the façades and plant flowerbeds where there’s asphalt.”

The resulting images revealed vibrant transformations, lush with trees, flowering beds, green facades and even solar-powered elements integrated into the urban fabric.

In Mainz, the AI reimagined Gutenbergplatz with plant-covered façades of the State Theatre, larger shaded trees and greenery sprouting between paving slabs.

Meanwhile in Stuttgart, the redesigned Marktplatz features rooftop gardens, green facades and a cooling pond in the square.

Visually stunning but not always practical: experts

Architect and urban climate expert Bernhard Lenz, from the Karlsruhe University of Applied Sciences, reviewed the AI-generated concepts.

He praised their visual appeal, calling the AI version of Mainz “very nice and green”. 

However, he expressed concern over the technical and functional limitations of the proposals.

For example, greening the ground extensively may look attractive but limits the flexibility of public spaces.

“Nothing else can take place in such an area, no weekly market, no public viewing,” Lenz pointed out, noting that many central urban locations already face intense competition for space.

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Not every tree can be planted

While the AI easily inserted large trees into its renderings, planting them in real life is often not so simple.

Urban environments, particularly those developed over centuries, are layered with underground infrastructure – water pipes, electricity lines, parking garages and tunnels – that complicate planting.

Nevertheless, Lenz maintains that trees are among the most effective tools in cooling city environments.

Where trees can’t be planted, he suggests alternatives such as artificial shading systems or water-based cooling structures.

 “Ideally, the sunshade system could be retracted at night,” he said, allowing built-up heat to escape into the night sky.

Stuttgart’s AI-enhanced green facades received notable approval from experts.

These vertical gardens offer two major advantages: they save ground space and significantly reduce surrounding air temperatures.

Lenz cited cooling effects of up to five to six degrees Celsius, with benefits felt even just a few metres away.

However, the city of Stuttgart expressed reservations.

Press officer Sven Matis noted that while the city supports green facades in principle, implementing them is complex.

They require watering systems, must be connected to the ground and pose challenges for fire safety.

Water remains a critical issue

One key element the AI proposals did not address is water supply.

With increasing droughts and irregular precipitation due to climate change, maintaining the health of added greenery – especially young trees and new plant beds – requires careful planning.

Sudden heavy rains, although dramatic, often don’t benefit long-term urban plant life.

“If we do not take countermeasures now, things will of course become increasingly dramatic,” Lenz warned. “Our cities will no longer be liveable at some point, at least not in the city centres and we must take action to counteract this now.”

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