All forecasts state that in the 21st century: there will be more urban. Thus, the majority of the population will live in cities. The urbanization model and the transport system of the city inherited from the 20th century have become disarticulated. There is a new trend for reinventing the frugal and sustainable city. This takes into account all the aspects of the ecological transition, especially energy, in the face of the climate challenge. This challenge is part of the Urban Project approach, which stems from postmodernist theory. The innovative idea of this collaborative intelligence aims to redesign the connected and more ecological city. This thinking is about green growth integrated with the carbon neutrality strategy. Today, this vision of urban renewal is based on sustainability which is a fundamental criterion in the eco-design of the safe and resilient city. It supports the use of renewable energies, the issue of climate change, the health emergency as well as the use of Green-Tech in ecological architecture and eco-urbanism, to serve strategic issues, especially environmental ones. The Urban Project will have to be multidisciplinary in the cross analysis of various themes. Moreover, this approach must be based on the judicious articulation of spatial and temporal scales. Also, this process must take into account contextual realities while favouring the ingredients of urban ecology. It is a question of supporting biodiversity, the green and blue grid, and above all the use of geo-sourced materials in the eco-construction of the low-carbon city. Certainly, this operational and interactive mode is complex. Consequently, it refers to multiple notions of transversality, partnership, governance and participatory democracy. This inclusive and concerted process is based on thinking-design, resulting from the fruitful meeting of public and private actors around an agile and acceptable city project for the post-carbon era.