Legislation passed in the 1970s and 1980s and updated in subsequent decades established mandatory federal minimum energy efficiency standards for equipment and appliances in buildings and fuel economy standards for light-duty vehicles (LDVs). Three scenarios in EIA’s Annual Energy Outlook 2018 (AEO2018) examine the impacts of varying energy efficiency policies on end-use consumption, including what could happen under current laws and what might happen if energy efficiency policies were made more or less stringent.