(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 shall provide that the savings in any year are guaranteed to the extent necessary to make payments under the contract during that year.

(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 ten years, and for the evaluation, recommendation, design, implementation and installation of energy conservation measures on an installment payment or lease purchase basis.