After building 2014's Aktivhaus B10, a house that generates twice as much energy as it uses for its own needs via renewable sources, architect Werner Sobek believes that we have all the technology we need to live in entirely emissions-free cities in only five years. He also understands that to make this shift, he will need the full support of the construction and automotive industries. 

“The automotive industry is driving forward the creation of ever more powerful, longer-lasting batteries," Sobek said. "At the same time, the construction industry is working on such solutions as a retrofittable building automation system that can noticeably reduce the energy consumption of existing buildings in a very short amount of time.”

Sobek believes that the efficient city model could be brought into being via a "Sisterhood Principle" of data sharing, whereby multiple houses, even city districts, exchange information about what energy they are using, storing, and generating, and correspondingly work to create an equitable balance between them. 

For the unabridged German version of Sobek's ideas, check out the video below: