The U.S. Department of Energy (DOE) is proposing a rule to implement provisions of the Energy Conservation and Production Act (ECPA), as amended by the Energy Policy Act of 2005 and the Energy Independence and Security Act of 2007, which require DOE to establish sustainable design principles for the siting, design, and construction of certain new Federal buildings and major renovations of Federal buildings (42 U.S.C. 6834(a)(3)). In addition, this rule would also establish regulations that require water conservation technologies and solar hot water heaters be applied to the extent life-cycle cost effective (42 U.S.C. 6834 (a)(3)(A)(ii)).  DOE previously issued a final rule under RIN 1904-AD62 that established standards for the use of third-party green building certification systems in the design of new Federal buildings which may be used in lieu of the Federal sustainable design standards that will be addressed in the forthcoming supplemental proposed rule (79 FR 61563).