Sustainable Codes

Desired Trend


Current Trend

Baseline (2013): 86.8%
Current (2022): 87.0%

Theme Green


Percent of local governments that have an energy conservation code and/or a green construction code

Why is it Important?

Local governments are uniquely positioned to promote sustainable development through local codes and ordinances. There are two model codes that local governments may adopt to improve the sustainability of buildings in their communities: the International Energy Conservation Code (IECC) and the International Green Construction Code (IgCC). These two codes are developed by national experts and may be adopted in whole or in part by local governments. The IECC provides a choice of prescriptive or performance-based standards for energy efficiency in residential and commercial buildings, and addresses topics such as lighting, heating and cooling, and insulation. The IECC is released every three years, with each version requiring higher levels of energy efficiency. The 2021 IECC was released in July 2021. Compared to the 2018 IECC, the 2021 codes are estimated to improve efficiency by 9.4 percent and improve carbon emissions by 8.7 percent. In addition, the revised codes provide more flexibility and clarification.1 The International Code Council estimates that in the first 20 years of existence the codes saved consumers at least $44 billion and reduced carbon dioxide emissions by 36 million tons.1 The IgCC is a relatively new code, first released in 2012, was also updated in 2021. IgCC provides standards for the design and construction process including materials and resource use, indoor environmental quality, and energy and water efficiency. This indicator measures the percent of local governments (cities and counties) that have adopted the IECC or the IgCC, as well as the percent of local governments where developments are subject to statewide IECC requirements.


How are we Doing?

As of 2022, at least 87 percent of the local governments in the St. Louis region have the International Energy Conservation Code (IECC), which corresponds to 174 out of 200 local governments. As of 2022, we are not aware of any local governments in the St. Louis region adopting the International Green Construction Code (IgCC).

In the state of Illinois, the Energy Efficient Buildings Act requires all construction occurring in jurisdictions that require building permits to comply with the 2018 IECC. Due to this law, all local governments in the St. Louis region in Illinois are considered to have the 2018 IECC. The Capital Development Board and the Department of Commerce and Economic Opportunity updated the Illinois Energy Conservation Code with the new code/2018 IECC effective July 1, 2019.

In the Missouri portion of the St. Louis region, seven local governments have partially of fully adopted the 2018 IECC, 61 local governments have partially or fully adopted the 2015 IECC, one has partially or fully adopted the 2012 IECC, and 42 have partially or fully adopted the 2009 IECC. One limitation to this indicator is that it does not account for the level of code compliance or enforcement. As one study of energy code compliance in Illinois found, some communities have a lack of political will to adopt the state-mandated energy conservation code, and others lack the resources (staff) to enforce the code.

Geographic Level

St. Louis eight-county bi-state region, including Franklin, Jefferson, St. Charles, and St. Louis counties and the city of St. Louis in Missouri and Madison, Monroe, and St. Clair counties in Illinois. View map.


1 IECC, Reasons for adopting the 2021 IECC, accessed at,existing%20requirements%20that%20provide%20clarification

Data Sources

International Code Council and East-West Gateway Council of Governments