The building envelope includes all the building components that separate the indoors from the outdoors. Building envelopes include the exterior walls, foundations, roof, windows and doors. The performance of the building envelope is impacted by a number of sub‐systems, such as heating, cooling and ventilating equipment, plumbing and electrical systems. The interaction of the sub‐systems with the components of the building envelope, as well as certain activities of the occupants, can affect the performance of the building envelope.
The building envelope, like a car, requires regular inspection and maintenance. If problems can be detected early, before obvious damage is caused, they can be remedied at much less expense and while any existing warranty programs are still in effect.