Sustainable construction begins with an efficient building envelope. As the single largest building element, the building envelope or building shell separates the interior of the building from the external environment and includes the roof, walls, windows, glazing, floors and all the joints in between. A high-performance envelope must meet the project’s requirements for acoustic, thermal, structural, visual, air-quality, fire-resistant, watertight, temperature-control and aesthetic needs. Along with this great responsibility, the building envelope presents great opportunities to enhance sustainability and reduce long-term costs of buildings throughout their life.