Building envelope

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A building envelope is the exterior assembly that encloses the interior space of a building. It serves as the outer shell to protect the indoor environment as well as to facilitate its climate control. Building envelope design is an application area that draws from all areas of building engineering, especially building science and indoor climate control.

Building envelope design includes four major performance objectives:

Structural integrity
Moisture control
Temperature control
Control of air pressure boundaries

Control of air includes air movement through the components of the building envelope (interstitial) itself, as well as into and out of the interior space, which affects building insulation greatly.

The physical components of the envelope include the foundation, roof, walls, doors and windows. The dimensions, performance and compatibility of materials, fabrication process and details, their connections and interactions are the main factors that determine the effectiveness and durability of the building enclosure system.

Common measures of the effectiveness of a building envelope include physical protection from weather and climate (comfort), indoor air quality (hygiene and public health), durability and energy efficiency. In order to achieve these objectives, all building enclosure systems must include a solid structure, a drainage plane, an air barrier, a thermal barrier, and may include a vapor barrier. Moisture control is essential in cold climates. See dew point, condensation, and toxic mold.