The vernacular architectures of dwelling in central Portugal — from the inland mountains to the coastal plains — reveal themselves as open systems that articulate form, matter, and flows in a finely tuned response to local conditions. From these cases emerges the concept of thermodynamic prototypes, whose timeless operative principles enable a rethinking of architectural design as a situated practice — rooted in the territory and culturally attuned — capable of responding to contemporary complexity. The work combines critical research, drawn observation, and multiscalar reading.