(a) General rule.--A guaranteed energy savings contract may provide that all payments, except obligations on termination of the contract before its scheduled expiration, shall be made over a period of time. Every guaranteed energy savings contract that requires payments over a period of time shall provide that, after the initial year of the contract, the savings in every subsequent year are guaranteed to the extent necessary to make payments under the contract during that year. A guaranteed energy savings contract, in addition to the quantification and guarantee of energy savings, shall expressly state, quantify and validate the budgetary sources of all energy-related cost savings and operating costs utilized to satisfy the financial obligations and performance during the term of the agreement.

(b) Written guarantee.--A guaranteed energy savings contract shall include a written guarantee that savings will meet or exceed the cost of the energy conservation measures to be evaluated, recommended, designed, implemented or installed under the contract.

(c) Payments.--A guaranteed energy savings contract may provide for payments over a period of time not to exceed 20 years and for the evaluation, recommendation, design, implementation and installation of energy conservation measures on an installment payment or lease purchase basis.

(d) Improvements not causally connected to an energy conservation measure.--An improvement that is not causally connected to an energy conservation measure may be included in a guaranteed energy savings contract if:

and the savings justification for the improvement is documented by industry engineering standards.

(e) Other expenditures.--A facility alteration which includes expenditures that are required to properly implement other energy conservation measures may be included as part of a guaranteed energy savings contract. In such case, notwithstanding any other provision of law, the installation of these additional measures may be supervised by the contractor performing the guaranteed energy savings contract.