What is the Building Envelope?
What is the Building Envelope? That is an excellent question and one we love to answer here at the Building Enclosure Blog.
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Answer
The building envelope is the part of the building that physically separates the building’s interior environment from the exterior environment. In short, it is the physical assembly that separates the inside from the outside.
Important clarification
This post’s title could well have been “What is the building envelope, and is it the same as the building enclosure?” since this is a ubiquitous question. Yes, we believe the building enclosure is the same as the building envelope, and while we prefer the term enclosure over envelope, we use both. If you want our full answer on this question, please refer to our article here.
From what is the building envelope made?
The envelope is intentionally constructed of particular assemblies to separate the interior environment from the exterior. Meaning, unless you are living in a cave or other naturally formed burrow-like environment, the envelope enclosing your space was purposely built in the way it was to fulfill specific functions.
These functions include but are not limited to protecting the occupants and contents on the interior by controlling the passage of moisture, air, and heat. It was likely also built to resist specific forces (like those imparted by snow, wind, and gravity) since if it were unable to do so, it would not control the passage of moisture, air, and heat for very long. (Think about that tent you tried to pitch in the middle of the blizzard of 06).
Materials, Components, Assemblies, and Systems
Speaking of a tent, while some building envelopes consist of only one component (at a particular section), most envelopes consist of multiple materials formed into various parts (components) combined in various assemblies to function as systems. For example, a typical exterior wall assembly consists of the exterior siding, building wrap, sheathing, studs, insulation, interior drywall, and paint. The assembly also includes any air gaps and voids since it contributes to the envelope’s control function.
Summary
Therefore, the building envelope includes all the assemblies that make up the foundation walls and slab, exterior walls (including doors, windows, louvers, vents, etc.), and roof. It is common practice in the envelope design, consulting, and commissioning fields to focus on ‘control layers’ when considering the envelope.
References, Credits, and Further Reading
AIA Definitions for Building Performance
