California air quality district accelerates zero-emission transition with updated ruling

The South Coast Air Quality Management District (South Coast AQMD) in California has updated a ruling that will require new and existing buildings to transition to zero-emission water heaters. Rule 1146.2 was adopted in January 1998 to regulate emissions from equipment fired with natural gases with heat input capacities of less than or equal to 2 million British thermal units (Btu) per hour.

The rule update is a part of the district’s 2022 Air Quality Management Plan, which is designed to improve air quality and meet federal air pollution standards by 2037. As part of the amendment, residential and commercial buildings, which have been a major source of greenhouse gas (GHG) emissions, will need to either replace or update water heating utilities to reduce air pollution. South Coast AQMD estimates the changes will help reduce GHG emissions by 5.6 tons per day.

The amendment will affect approximately 1 million units within the South Coast AQMD’s jurisdiction. All new equipment must meet a nitrogen oxide (NOx) standard before being installed. The South Coast AQMD will also introduce alternative compliance options to give more time to transition to zero-emission technologies. These alternatives apply if:

• Utility upgrades are necessary.
• Multiple units must be replaced within two consecutive years.
• Emergency replacements are needed.
• An instantaneous water heater in a mobile home must be replaced.
• A new unit is required in a property under lease relying on landlords to upgrade electricity.
• Construction is needed to expand spacing or relocate a unit.

The amendment specifies that existing units may reach the end of their unit age before transitioning to zero-emission replacements. This allows residences and small businesses to meet zero-emission limits through natural replacement rather than replacing them once they reach a defined age.

The updated Rule 1146.2 will go into effect Jan. 1, 2026. Implementation dates will vary based on what types of units will be replaced, whether the buildings are new or existing and the size of the units. South Coast AQMD is developing a Zero-Emission Rebate Program to help residential and commercial buildings with zero-emission transition. The program will prioritize overburdened communities.