as the Secretary may identify and adopt by regulation, as may be necessary for purposes of this paragraph, except that the Secretary shall make a determination regarding whether to adopt and apply any such requirements, standards, checklist, or rating system for purposes of this section not later than the expiration of the 180-day period beginning upon date of receipt of any written request, made in such form as the Secretary shall provide, for such adoption and application. (5) Green building For purposes of this subsection, the term green building means, with respect to standards for structures, standards to require use of sustainable design principles to reduce the use of nonrenewable resources, minimize the impact of development on the environment, and to improve indoor air quality. (6) Energy audits The Secretary shall establish standards and requirements for energy audits for purposes of paragraph (3)(A)(ii). (7) Applicability and updating of standards (A) Applicability Except as provided in subparagraph (B), the requirements, standards, checklists, and rating systems referred to in this subsection that are in effect for purposes of this subsection are such requirements, standards, checklists, and systems are as in existence upon the date of the enactment of this Act. (B) Updating For purposes of this section, the Secretary may adopt and apply by regulation, as may be necessary, future amendments and supplements to, and editions of, the requirements, standards, checklists, and rating systems referred to in this subsection. (c) Authority of Secretary To apply standards to federally assisted housing and programs (1) HUD housing and programs The Secretary of Housing and Urban Development may, by regulation, provide for the applicability of the energy efficiency standards under subsection (a) or the enhanced energy efficiency and conservation standards and green building standards under subsection (b), or both, with respect to any covered federally assisted housing described in paragraph (3)(A) or any HUD