105 ILCS 5/19b-4
The guaranteed energy savings contract shall include a written guarantee of the qualified provider that either the energy or operational cost savings, or both, will meet or exceed within 20 10 years the costs of the energy conservation measures. The qualified provider shall reimburse the school district or area vocational center for any shortfall of guaranteed energy savings projected in the contract. A qualified provider shall provide a sufficient bond to the school district or area vocational center for the installation and the faithful performance of all the measures included in the contract. The guaranteed energy savings contract may provide for payments over a period of time, not to exceed 20 years from the date of final installation of the measures.
105 ILCS 5/19b-4