This standard applies to existing buildings@ portions of buildings@ and building complexes@ including the envelope and all systems in the building. This standard excludes industrial and agricultural processes in buildings for which the energy targets do not include those processes. PURPOSE This standard provides criteria that will result in reduced energy consumption through improved energy efficiency and performance in existing buildings. This standard is directed toward providing procedures and programs essential to energy efficient operation@ maintenance@ management@ and monitoring; increasing the energy efficiency of the energy-using systems and components; and upgrading the thermal performance of the building envelope.