Like plants and animals, humans have also adapted to environmental constraints over the millennia. Additionally, buildings have evolved to respond to their environment. Bioclimatic building design is an engineering practice that concentrates on a building's performance in relation to its specific climatic conditions and the occupants’ needs. This goal can be achieved through various approaches, including the use of passive solutions or active mechanical measures. However, in light of the need to reduce environmental impacts, passive solutions at the building envelope level are preferred, as they directly influence the operational energy performance of buildings without requiring additional energy, while offering higher levels of indoor comfort. Central to the concept of bioclimatic building design is the understanding that the most sustainable approach to designing buildings is, firstly, to adapt them to the environment and their occupants, and, secondly, to apply cutting-edge technologies to ensure their proper functioning throughout their entire life cycle. This chapter will explore the historical context of bioclimatic design, its fundamental principles, and the role of building envelopes in achieving thermal comfort.