Cities concentrate opportunities and exchanges, culture and business, while, at the same time are a key contributor to climate change. They are highly complex organisms, with multiple actors involved, that bring to light underlying social interests and conflicts present in society. In 2007, the world's urban population surpassed the rural and this difference has been increasing ever since. According to the 2018 Revision of World Urbanization Prospects report, 55% of the world's current population lives in urban areas, rising to 68% by 2050. This will represent an increase of 2.5 billion people in urban areas, with almost 90% of this increase occurring in Asia and Africa. The Smart Sustainable Cities: Reconnaissance Study also points out that urban centers account for 67% of global energy demand, emit 70% of greenhouse gases and, on top of it all, buildings consume 40% of all energy worldwide. The prospect of a mostly urban world, along with the alarming onset of climate change, both raise challenges regarding living conditions in the coming decades and centuries, and all the implications that will accompany these changes.

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