; and (2) by striking subsections (c) and (d) and inserting the following: (c) Periodic review The Secretary shall— (1) once every 5 years, review the Federal building energy standards established under this section; and (2) on completion of a review under paragraph (1), if the Secretary determines that significant energy savings would result, upgrade the standards to include all new energy efficiency and renewable energy measures that are technologically feasible and economically justified. . 423. Enhanced energy efficiency underwriting (a) Definitions In this section: (1) Covered agency The term covered agency — (A) means— (i) an executive agency, as that term is defined in section 102 of title 31, United States Code; and (ii) any other agency of the Federal Government; and (B) includes any enterprise, as that term is defined under section 1303 of the Federal Housing Enterprises Financial Safety and Soundness Act of 1992 ( 12 U.S.C. 4502 ). (2) Covered loan The term covered loan means a loan secured by a home that is issued, insured, purchased, or securitized by a covered agency. (3) Homeowner The term homeowner means the mortgagor under a covered loan. (4) Mortgagee The term mortgagee means— (A) an original lender under a covered loan or the holder of a covered loan at the time at which that mortgage transaction is consummated; (B) any affiliate, agent, subsidiary, successor, or assignee of an original lender under a covered loan or the holder of a covered loan at the time at which that mortgage transaction is consummated; (C) any servicer of a covered loan