Glossary
Building Envelope
Plain-Language Definition
The physical barrier between the conditioned interior and the exterior environment — comprising walls, roof, windows, doors, and foundation. The envelope controls heat transfer, moisture, air infiltration, light, and noise.
Technical Context
Envelope performance is measured by: U-value (thermal transmittance), SHGC (Solar Heat Gain Coefficient) for glazing, air tightness (ACH at 50 Pa), and vapour permeability. ASHRAE 90.1 prescribes envelope requirements by climate zone. In hot-humid climates like Bangladesh, controlling solar heat gain and moisture is critical.
Why It Matters
The building envelope determines 25-40% of a building's energy consumption. A poor envelope means the HVAC system works harder — higher energy cost, more maintenance, shorter equipment life. Envelope defects (leaks, thermal bridges, failed sealants) cause water damage, mould, and occupant discomfort.
Related Terms
Related Articles
Explore in-depth articles related to this topic in the Knowledge Library.
Search Knowledge Library →