Foundations
The foundation is a somewhat invisible component of a building. Attention to good foundation design and construction has significant benefits, however, and can help avoid some serious future problems. Good foundation design and construction practice means not only insulating to save energy, but also providing effective structural design as well as moisture, termite, and radon control techniques where appropriate.
While saving energy may be the primary reason for understanding good foundation design practices, there are other related benefits. For example, insulating any type of foundation is likely to result in warmer floors during winter in above-grade spaces, thus improving comfort as well as reducing energy use. Insulating basement foundations creates more comfortable conditions in below-grade space as well, making it more usable for a variety of purposes at a relatively low cost. Raising basement temperatures by using insulation can also reduce condensation, thus minimizing problems with mold and mildew. In addition to energy conservation and thermal comfort, good foundation design must be structurally sound, prevent water and moisture problems, and control termites and radon where appropriate.
The importance of these issues increases with an energy-efficient design because there are some potential problems caused by incorrect insulating practices. Under certain circumstances the structural integrity of a foundation can be negatively affected by insulation when water control is not adequate. Without properly installing vapor barriers and adequate air sealing, moisture can degrade foundation insulation and other moisture problems can actually be created. Improperly installed foundation insulation may also provide entry paths for termites. Insulating and sealing a foundation to save energy results in a tighter building with less infiltration. If radon is present, it can accumulate and reach higher levels in the building than if greater outside air exchange was occurring.