This legislation, known as the "Federal Mechanical Insulation Act," clarifies that the installation of mechanical insulation property is an eligible energy or water efficiency measure for federal buildings. It specifically amends the National Energy Conservation Policy Act to include this provision, thereby promoting greater energy and water conservation in government facilities. The bill defines mechanical insulation property as insulation materials, facings, and accessory products used in connection with a mechanical system that meet or exceed the American Society of Heating, Refrigerating and Air-Conditioning Engineers Standard 90.1 and reduce energy loss. Consequently, comprehensive energy and water evaluations conducted in federal buildings will now explicitly identify and consider the installation of mechanical insulation property as a key energy- and water-saving measure.