The ordinance amends the Municipal Code of Chicago to impose new limitations on combustion in both new buildings and existing structures undergoing significant additions. It introduces definitions such as "COMBINED HEAT AND POWER SYSTEM" and "INDUSTRIAL PRODUCTION," while deleting the definition of "code official." The primary goal of the ordinance is to control carbon dioxide emissions from buildings, which contribute to approximately 70% of the city's carbon footprint, thereby protecting public health and addressing climate change. The ordinance highlights the adverse health effects of elevated carbon dioxide levels, particularly in communities that are disproportionately affected by respiratory issues.

In addition to the combustion limitations, the ordinance establishes specific requirements for commercial buildings that exceed the Illinois Energy Conservation Code. It prohibits the combustion of substances emitting 25 kilograms or more of carbon dioxide per million British thermal units, with exceptions for electricity generation, emergency standby, and certain operational activities. The ordinance also updates terminology from the "Chicago Energy Conservation Code" to the "Chicago Energy Transformation Code," effective November 1, 2022, and mandates a market segmentation study to enhance understanding of the building stock and improve energy efficiency strategies. The ordinance will take effect upon passage and approval.