What cities can learn from nature

From droughts and famines to floods that wash away entire communities to devastating earthquakes and record-breaking temperatures all over the world, extreme weather events are becoming increasingly frequent – welcome to climate change. Urgent action is needed wherever humans are actively and extensively interfering with nature. And this is particularly common in our cities. Impervious surfaces, materials that retain heat and precious few green spaces to balance this out are among the reasons why, according to Germany’s Nature and Biodiversity Conservation Union (NABU), average temperatures in cities are 10°C higher than in rural regions and why meteorologists talk about urban heat islands. As a result, today’s cities are actively contributing to global climate change.

Glass façades dominate the cityscape of many metropolises. Whether in New York, Shanghai or Frankfurt, glass skyscrapers are eye-catching – unfortunately, they also have a detrimental effect on the urban climate. Because their façades heat up as soon as the sun shines on them, they act like heating elements in an oven and cause big cities to overheat.

But why is that? Natural surfaces store rainwater and then release about 60 per cent of it on hot days through evaporation. That’s also how forests keep themselves cool. Impervious surfaces such as roads or building façades, on the other hand, only release 10 per cent of the rainwater through evaporation. As well as providing insufficient cooling, this can also result in flooding after heavy rain.

One idea that could counteract this problem is currently being tested on the campus of the University of Stuttgart. It’s all about hydroactive elements – specifically, a façade element called HydroSKIN. It works like this: the outside consists of a water-permeable textile cover, which allows raindrops in, but keeps other impurities out. On the inside, the water is channelled into a reservoir. When the sun shines with more intensity again, the collected water is fed back into the façade element, where there are two layers of fabric with a space in between. This generates the air circulation needed to trigger the evaporation of the collected rainwater and provide a natural cooling effect for the façade.

According to the research team, initial lab tests have already demonstrated a 10°C temperature reduction. So this is a process that could not only cool the urban climate, but also collect excess water and protect against flooding.

Another approach is the urban forest garden. What actually seems obvious turns out to be a creative idea – and one that has yet to take root in Germany. The idea behind urban forest gardens is to bring fruit and vegetable cultivation into the middle of cities. They are meant to imitate the structure of a forest, as Jennifer Schulz, landscape designer, scientist and initiator of the first German project in Berlin explained in an interview with German radio station Deutschlandfunk: “The tree layer is formed by fruit trees, the shrub layer by berry bushes, the herb layer by vegetables and herbs”.

This multi-layered system is designed to activate the ecological processes of a forest and be able to store a lot of water. At the same time, the natural evaporation effect can help to bring down temperatures in the urban environment.

Furthermore, initiatives like the one in Berlin are intended to act as community garden projects for local residents, encouraging them to grow their own fruit and vegetables and educating them about nutrition. While urban forest gardens already exist in the UK and in the USA, where they’re known as urban food forests, comparable projects such as the ones in Berlin and Kassel are still in their infancy in Germany.

It’s vital that we lessen the impact of urban heat islands and create a pleasant urban climate for people and the environment. Projects like these give us hope and show how cities can still be good places to live in the years to come. But the fact is that, to make our cities modern and fit for the future, we’ll need more of these kinds of creative solutions and innovative technologies – and we’ll have to implement them, too.

You’ll find many creative solutions and groundbreaking technologies, especially for the interior design industry, at the imm cologne Spring Edition from 4 to 7 June 2023 – secure your ticket now: https://www.imm-cologne.de/die-messe/tickets/tickets-kaufen/