While in the recent decades, the field of architecture has primarily focused on the self-sufficiency of individual buildings, the current ARDETH issue wishes to bring back scholarly attention to an approach that prioritizes energy conservation and generation at the urban scale. Such an approach relies on the idea of the productive (and not only consumptive) urban environment, in which the built fabric, topography, soil, bodies of water, green spaces, as well as regional climatic conditions (determined by sun, wind, rain flows, and seasonal temperatures), serve as potential parameters for energy production. How do different built fabric densities contribute to and limit the emergence of post-carbon energy landscapes? What are the implications of a British suburb, an Italian medieval town, or Greek informal settlements densities on the production, distribution, and use of post-carbon energy in those areas?