Building science is the study of interactions between the various materials, products and systems used in building construction and their impact on the uses and occupants of the buildings and the environments they are located in.
A building envelope is a set of elements and/or systems that play the role of separating differing environments, as well as of protecting building occupants and materials. A building envelope also functions to control the exchanges that occur between the inside and the outside environment to which it is exposed.
It is the understanding of physical principles related to air, heat and moisture flow, and their effects, that allows the development of building envelope assemblies that can adequately contribute to the control of the inside environment while respecting performance and durability criteria.