Appendix J Clean Air Delivery — 2025 California Mechanical Code

(Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

This state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.

APPENDIX J

CLEAN AIR DELIVERY

The provisions contained in this appendix are not mandatory unless specifically adopted by a state agency, or referenced in the adopting ordinance.

This appendix provides criteria for an increased protection level for occupant health by delivering and monitoring clean air in occupied areas of certain buildings. The provisions contained in this appendix are not mandatory unless specifically referenced in the adopting ordi nance.

In groups A, B, E, and I occupancies, each mechanical system shall meet the requirements in Section J 201.1.1.

Exception: Occupiable spaces where 100 percent of the supply air meets High-Efficiency Particulate Air (HEPA) filtration.

J 201.1.1 Airflow for Increased Filtration. Mechanical systems shall be sized to accommodate a design airflow at a total static pressure drop which assumes the utilization of a supply air filter with a Minimum Efficiency Reporting Value (MERV) of no less than 13.

Group A, B, E and I occupancies shall be equipped with a minimum of one carbon dioxide sensor for every 500 square feet (46.45 m [2] ) of occupiable space. Carbon dioxide sensors installed in accordance with this section shall meet the requirements in Sections J 301.1.1 and Section J 301.1.3 Mechanical equipment serving each zone(s) shall be equipped with controls which meet the requirements in Section J 301.1.2.

J 301.1.1 Carbon Dioxide Sensor Performance Specifications. Carbon dioxide sensors installed in accordance with Section J 301.0 shall comply with the following carbon dioxide measurement specifications as certified by the equipment manufacturer:

(1) Range lower bound less than or equal to 400 ppm.

(2) Range upper bound greater than or equal to 2000

ppm.

(3) Accuracy within ±75 ppm at a reading of 1000 ppm.

(4) Output resolution of 20 ppm or less. J 301.1.2 Mechanical System Controls. Controls installed in accordance with Section J 301.0 shall comply with the following:

(1) Receive data from the carbon dioxide sensor in the occupiable zone(s) at least once per 15 minutes.

(2) Be calibrated to provide pre-established outdoor airflow rates, or be equipped with the necessary instrumentation to measure outdoor airflow rate.

(3) Be capable of adjusting the outdoor airflow in response to an adjustable outdoor airflow setpoint.

(4) Increase the amount of outdoor air provided to each occupiable zone until the carbon dioxide level in each occupiable zone falls below a maximum threshold as defined by the user.

J 301.1.3 Carbon Dioxide Detection Threshold

Level. The default detection threshold level for carbon dioxide measurement above which triggers an alert in accordance with Section J 301.1.4 shall be set to 1100 parts per million (ppm). The end user can modify the detection threshold level based on specific operations and needs.

J 301.1.4 Carbon Dioxide Detection Threshold

Level Exceeded. When carbon dioxide levels exceed

the detection threshold level established in Section J 301.1.3, the mechanical equipment shall modify the outdoor airflow rate as required in Section J 301.1.2. When the carbon dioxide concentration remains above the detection threshold level for a period of 30 minutes or more, the occupants in the zone shall be alerted by approved audible and visual notification devices or through a building monitoring system.