Insulation has no moving parts. Most of it is not visible once it is installed. Although insulation is not glamorous, it is very important. An occupant’s comfort within a home, and the cost of maintaining that comfort level, is determined by how well the habitable space of a home is insulated. Further, the integrity and condition of a home are influenced by the effectiveness of the insulating system. This Unit presents the basics of heat transfer. In addition, the Unit discusses in detail the four components of a home insulating system: insulation, air leakage prevention, moisture control, and ventilation.