or joint resolution, or amendment thereto or conference report thereon, that provides the authority to enter into or modify any covered energy savings contract on a net present value basis (NPV). (b) NPV calculations The net present value of any covered energy savings contract shall be calculated as follows: (1) The discount rate shall reflect market risk. (2) The cash flows shall include, whether classified as mandatory or discretionary, payments to contractors under the terms of their contracts, payments to contractors for other services, and direct savings in energy and energy-related costs. (3) The stream of payments shall cover the period covered by the contracts but not to exceed 25 years. (c) Definition As used in this section, the term covered energy savings contract means— (1) an energy savings performance contract authorized under section 801 of the National Energy Conservation Policy Act