Ill. Admin. Code tit. 44 § 1400.4526
Notwithstanding any rule, regulation, statute, order, or policy of any kind, the Treasurer's office shall contract for supplies and services that are environmentally preferable. If, however, contracting for an environmentally preferable supply or service would impose an undue economic or practical hardship on the Treasurer's office, or if an environmentally preferable supply or service cannot be used to meet the requirements of the Treasurer's office, then the Treasurer's office need not contract for an environmentally preferable supply or service. Specifications for contracts, at the discretion of the Treasurer's office, may include a price preference of up to 10% for environmentally preferable supplies or services. [30 ILCS 500/45-26 ]
Ill. Admin. Code tit. 44, § 1400.4526