ABSTRACT
The term thermal envelope refers to the shell of the building as a barrier to the loss of interior heat or to the penetration of unwanted outside heat into the building. It refers to the walls, windows, roof and basement floor of the building. The building envelope is more than a thermal barrier, however, as it contributes to the structural integrity of the building and serves as a barrier to moisture, the infiltration or exfiltration of air and noise. These functions are tightly coupled, such that measures that lead to a higher quality thermal barrier will lead to improvements in the envelope as a barrier to wind and rain, thereby reducing maintenance costs and increasing the lifespan of the building envelope. For example, measures to eliminate thermal bridges (places where there are gaps in the insulation or highly conductive materials bridging from indoors to outdoors) reduce the likelihood of condensation and all the problems associated with condensation. Thermally tight buildings will have smaller spatial variations in temperature and lower noise from outside, contributing to a higher-quality and more comfortable indoor environment.
