Power Thesaurus. (2015). scavenger thesaurus. Retrieved October 15, 2015, from http://www.powerthesaurus.org/scavenger/antonyms.
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.
This is the equivalent of saying that heat is the energy transferred from a hot system to a cold system. Before it is transferred, the energy which remains within the boundary of the system is not heat, but internal energy or total available energy.