On August 13, 2004, Illinois Governor Rod Blagojevich signed House Bill 4099 (HB 4099) into law. HB 4099 created the Energy Efficient Commercial Building Act, requiring statewide adoption of the commercial buildings requirements of the 2000 International Energy Conservation Code (IECC) with a 2001 Supplement.

The Illinois Capital Development Board (CDB) is responsible for the rulemaking process to establish the procedural criteria for code implementation. The Department of Commerce and Economic Opportunity (DCEO) is responsible for the outreach and training programs to educate code officials, designers and contractors about the details of the new code.

The CDB is the construction management arm of Illinois' state government. The CDB oversees design and construction of new state structures, including elementary and high schools, college and university facilities, public safety centers, museums and historic sites, state recreation areas, health centers, office buildings, prisons and other state facilities.

DCEO works to enhance Illinois' economic competitiveness by providing technical and financial assistance to businesses, local governments, workers and families. As the state's lead economic development agency, DCEO works to capitalize on Illinois' strengths as a center of transportation, manufacturing and technology development. DCEO administers a wide array of programs and services designed to help Illinois businesses thrive in the global economy. The state organization is committed to forging partnerships with the private sector in an effort to build upon Illinois' reputation as a center for business and industry.