A facility’s building envelope can make or break utility bills and energy-efficiency goals. As a barrier that keeps indoor temperatures inside and outdoor temperatures outside, the building envelope includes the foundation, exterior walls, insulation, roof, windows, and exterior doors. The quality of the building envelope can also impact indoor air quality and humidity levels, and have an effect on water infiltration.

https://northamerica.llumar.com/window-film-blog/commercial-window-film-blog-llumar/controlling-energy-use-through-the-building-envelope