the process that keeps heat from being transferred between two substances is
HEAT TRANSFER THROUGH CONVECTION. Like conduction and unlike radiation, convection requires a medium. However, in conduction the heat is transferred from one molecule to another, whereas in convection the heated fluid itself is actually moving. As it does, it removes or displaces cold air in its path.
Heat transfer can never be stopped, it can only be slowed or reflect away. The purpose of insulation is to impede this natural process. In hot weather, you want to stop heat from being transferred into the building, and in cold weather you want to stop it from being transferred out.