Which of the following best describes a “building enclosure”?

A "building enclosure" refers to an assembly of components that work together to separate the interior of a building from the external environment. This assembly typically includes walls, roofs, windows, and doors, which play a critical role in regulating the indoor climate, protecting against the elements, and ensuring energy efficiency. The enclosure acts as a barrier to moisture, air, and thermal transfer, thus significantly impacting the overall performance of the building.

In contrast, internal walls and ceilings focus solely on the partitioning and aesthetic aspects within a building, which do not address the environmental separation that is essential for a building enclosure. A framework for structural support relates to the skeleton of the building that holds it up, but it does not emphasize the enclosure's function in separating the interior and exterior environments. Lastly, while decorative features can enhance the visual appeal of a building, they do not define or fulfill the essential functions of a building enclosure related to environmental separation and performance. Therefore, the definition that encompasses the comprehensive role of a building enclosure is best captured by the assembly of components for environmental separation.