Recently, in the light of climatic changes all over the world and technical developments, the building envelope, which is part of a physical system that includes internal and external environments and serves as a physical barrier between them, has become one of the most important studies of building science. These studies have led it to a change in building techniques, materials, designs and concepts of some building envelopes that have emerged all over the world. The building envelope materials are no longer just a cladding that have a secondary role in influencing the cultural appearance and character of the building, but turned into one of the important tools in functionality. This change has reflected in the evolution of the envelope capability to transform its main role from just a barrier to providing a comfortable indoor environment for occupants of the building, as described in all relevant definitions of the envelope, to an envelope that is also responsible towards the external natural environment to restore its quality rather than the negative effects it was causing to this environment.
Despite these changes that impose themselves, there are inefficiencies in its practice at the local level, especially in the development projects in new cities, due to many local architects are lack of knowledge of the new capabilities of the building envelopes. In this context, the study seeks to gain a deep understanding of the relationship between the building material, the building envelope and its external environment, and to highlight the growing need for such envelopes. Therefore, the research discusses this subject through two axes; the first axis examines the key definitions of the building envelope and analyzes its composition to take advantage of it in formulating the proposed definition. Followed by a study of the impact of the building envelope on the external natural environment by analyzing several international experiences. While the second axis tends to make a modest attempt to formulate a proposal for a new definition, illustrating the emerging capabilities of the envelope towards the external environment, as the definition has important theoretical and practical impacts in applying the concept that highlighted in.