The envelope controls four flows: heat by insulation, air by the air barrier, water vapor by vapor control layers, and liquid water by cladding and flashing. Its quality sets the conduction, solar and infiltration loads that HVAC equipment must meet, and gaps in it cause condensation, drafts and mold. HVAC designers start from envelope details, because a better envelope means smaller, quieter equipment.
Building envelope on this one is tight and well insulated, the ventilation load is going to dominate, size for latent.
Also heard as
- envelope
- thermal envelope
- building shell
Related terms
Infiltration
Outdoor air that sneaks into a building through gaps in its shell, pushed by wind, stack effect and fans rather than by design.
Stack effect
The buoyancy-driven airflow that pushes warm air out the top of a building and pulls outdoor air in at the bottom.
Cooling load
How much heat and moisture a cooling system has to pull out of a space each hour to keep it at design conditions.
Building pressurization
Controlling the air pressure inside a building relative to outdoors, usually by bringing in more outdoor air than is exhausted.