ASHRAE STD 100 2015 Edition, January 28, 2015
Energy Conservation in Existing Buildings
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.
This standard provides criteria that will result in energy efficiency 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.