If, however, contracting for an environmentally preferable supply or service would impose an undue economic or practical hardship on the contracting State agency, or if an environmentally preferable supply or service cannot be used to meet the requirements of the State agency, then the State agency need not contract for an environmentally preferable supply or service. Specifications for contracts, at the discretion of the contracting State agency, may include a price preference of up to 10% for environmentally preferable supplies or services.
30 ILCS 500/45-26