Assessment of Residential Natural Gas Emissions

Measuring post-meter natural gas methane leaks in California residences

Lawrence Berkeley National Laboratory


Berkeley, CA

Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Result

Researchers completed field measurements of methane emission from homes. About 75 single-family homes from both northern and southern California were measured. Researchers found that emissions come from a combination of whole house leaks, continuous operation of pilot lights, and episodic operation of combustion appliances. Analysis shows that under the quiescent condition (no operation of appliances), the pilot lights contribute about 30% of the indoor emissions. The results suggest that repairing leaks, updating combustion appliances (e.g. replacing the pilot light with electronic ignitions), and electrification of appliances will greatly reduce methane emissions from the residential sector. The final report is posted on the Commission website, publication number CEC-500-2018-021
[placeholder /]. The results have been shared with the Air Resource Board to advise the greenhouse gas inventory database.

The Issue

Natural gas leakage emissions from California's energy infrastructure are estimated to be ~40 billion cubic feet/year, or ~2% of total natural gas consumption. Identifying and controlling these losses would provide benefits for local safety, regional air quality, and global climate. One important subsector of natural gas infrastructure that has not been carefully evaluated is residential structures, including single-family homes and multi-unit buildings. While this leakage is typically assumed to be small, residential usage accounts for ~22% of total natural gas consumption in California and the potential for losses could easily constitute a significant fraction of total emissions.

Project Innovation

This project estimates methane emissions from the "after meter" natural gas system in California residences. The research team designed a study and trained subcontractors to conduct building methane leakage measurements in approximately 75 sample houses. The researchers analyzed the field data to quantify the emission rates from these homes.

Project Benefits

This project measures post-meter natural gas methane leaks in a representative sample of single-family California residences, estimates the distribution of likely leaks, and determines total residential methane leakage. The results will be very important for the California Air Resource Board to update the state GHG inventory and to give greater insight to the climate impacts of natural gas consumption.

Environmental & Public Health

Environmental Sustainability

Methane is a potent greenhouse gas. The project identifies and quantifies after-meter sources of methane leakage from this sector. Project results found emissions from appliances to be about 10 times the 2015 state inventory estimates for residential natural gas methane emissions. The results provide critical information for greenhouse gas emission inventory and potential mitigation efforts by state and local agencies.

Key Project Members

Project Member

Marc Fischer

Staff Scientist



Richard Heath and Associates, Inc.


Contact the Team