The design of building envelopes is a delicate balance of energy related factors and non-energy factors. A well-designed envelope that gives careful consideration elements such as heat transfer and air leakage allows for buildings to save on energy. For example, using materials with high R-values can help provide better insulation and reduce mechanical loads and/or even reduce the size of the mechanical equipment required. Also, well-designed building envelopes are a critical piece to achieving net-zero buildings.
A well-designed envelope also takes into consideration non-energy elements such as daylighting and indoor air quality, which can lead to higher occupant satisfaction and productivity. The most critical of these design factors may very well be moisture mitigation as it can have significant energy and non-energy impacts. For example, moisture infiltration can lead to the corrosion of envelope insulating elements, which in turn can lead to higher levels of infiltration and mechanical systems having to use more energy to heat/cool buildings. Furthermore, moisture infiltration can lead to mold growth, which can have adverse effects on building occupant health.
Envelope commissioning is a critical step to ensure design criteria (as described above) have been addressed and met - both energy and non-energy. Please refer to the Commissioning (Cx) section for more information.