In the context of an international project promoted by ArcelorMittal a new concept of modular housing, focussing on uni-familiar dwellings, was developed by a Portuguese team from the University of Coimbra. The proposed solution intends to explore the potential of cold-formed steel structures, both in terms of spatial flexibility and ability for future expansion. Inspired by the Tetris game, the concept was developed in order to be evolutionary and easily adaptable to the multiple urban requirements of dwellings (houses in-band, semi-detached or isolated). Although the dwelling was the focus of the project, the concept may also be applied for collective housing. A complementary paper presented in this conference (part 2) describes the functional, structural and technological aspects of the project.