To accomplish this, Guallarte wants to bring sustainable industries and agriculture to our urban centers, with greenhouses atop every building. But in order for Guallarte’s proposal to work, he says, cities will have learn to submit to the laws and principles of nature. Urban planners also have big plans for our energy supply. In the future, countries like Germany could become energy producers. In Esslingen am Neckar, residents are working on producing green hydrogen in homes, to be used as fuel for trucks. It’s a project that‘s breaking new ground, says investor Manfred Norbert. Our future cities will be all about redefining a new normal. Architects and urban planners are expecting to see entirely new approaches to communal living, as well as new urban concepts for autonomous supply chains. The repurposing of old buildings, and the generation of food as well as energy, are other important topics. The architect Arno Brandhuber thinks the current building stock available, and the possibilities it offers, have been underestimated. His spectacular business headquarters are located in an old silo in Berlin’s Lichtenberg district. His most provocative project, something he calls his "Anti-villa," is a repurposed East German factory for cotton knitwear. It‘s a prime example of sustainable design.