American Energy Efficiency Act of 2019 This bill directs the Department of Energy (DOE) to prescribe a federal energy efficiency resource standard for retail electricity and natural gas suppliers. Among other things, the bill establishes procedures and standards for evaluating, measuring, and verifying electricity and natural gas savings, including specifying the types of energy efficiency and energy conservation measures that may be counted; certain requirements governing retail electricity suppliers; other requirements governing applications for, and implementation of, delegated state administration; rules to govern transfers of electricity or natural gas savings between suppliers and third-party efficiency providers serving the same state and between suppliers and third-party efficiency providers serving different states; performance standards for retail electricity and natural gas suppliers; and penalties for suppliers who fail to document the adequate savings required by this bill.