Building Envelope Overview

What is a building envelope?

The building envelope is the skin or shell of a building, it's the physical separator between the interior and the exterior of the building. The envelope is made up of all the exterior components of the building, including the walls, roofing, foundations, windows, and doors. 

Building Envelope Fenestrations Building Envelope Penetrations
  • windows
  • doors
  • skylights
  • pass-throughs
  • mail slots
  • drop boxes
  • gaps
  • cracks
  • electrical boxes
  • conduit
  • pipes
  • outlets
  • light fixtures
  • wires - phone, cable
  • exit signs

Examples of Building Envelope Fenestrations:

Building Fenestrations

 

Examples of Building Envelope Penetrations:

Building Penetrations

 

Heat Transfer Through a Building Envelope

 Heat is transferred across the building envelope. If it’s a hot day the heat will want to get into the building and if it’s a cold day heat will want to get out. Knowing how fast the heat transfers from one side of the wall to the other will determine how hard your HVAC system needs to work, and how much energy it uses, to keep the indoor temperature comfortable.

The speed of heat transfer depends on the materials of the wall. For example, drywall, concrete, wood, steel, insulation, etc. Engineers measure the heat transfer through a material by using its calculated U-value (a low U-value is good, and a high U-value is bad). The inverse of a U-value is the R-value, which is the resistance to heat transfer.