**Abstract**

The horizon of sustainability calls into question extremely complex phenomena, both in terms of social, economic, and cultural transformations, and in terms of the ecological implications of building activity in its wide territorial and temporal extension, and in terms of and the techniques to refer to. On this last aspect, in particular, today it is necessary to counteract the tendency toward an inconsiderate simplification of the aforementioned complex phenomena, because this simplistic approach is precisely the cause of the often trivialized and sometimes radically wrong interpretations. The chapter develops the theme of environmental sustainability precisely in this complex perspective, assuming the consideration of the entire life cycle of building products, whether they are materials, components, or buildings, as an inescapable reference horizon and the measurement of energy and resource consumption and of the impacts that are determined along the life cycle (Life Cycle Assessment—LCA) as the main tool for assessing the concrete sustainability of design choices with rigor and scientific basis.

**Keywords:** life cycle assessment, built environment, architecture, buildings, life cycle thinking, design process, regenerative development
