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Nonresidential Indoor Air Quality

Nonresidential Indoor Air Quality and Ventilation

Codes and Standards Enhancement (CASE) Report

The Statewide CASE Team is requesting feedback on the 2019 Title 24, Part 6 Draft CASE Reports. The CASE Report presents pertinent information that supports the code change proposal. Please email feedback to You may also submit written comments to the Energy Commission. See the agenda for Energy Commission pre-rulemaking workshop (available here) for instructions on how to submit comments to the Energy Commission’s docket.

Measure Description

This measure proposes revising Title 24, Part 6 requirements using a combination of the requirements in Title 24, Part 4, ASHRAE 62.1-2016: Ventilation for Acceptable Indoor Air Quality (ASHRAE 62.1), and leveraging current research on indoor air quality. The ventilation requirements in Title 24, Part 4 are based on or reference ASHRAE 62.1. Therefore, aligning Title 24, Part 6 with select sections in Title 24, Part 4 will concurrently align with the corresponding section in ASHRAE 62.1. All of the proposed changes would impact the mandatory requirements for ventilation in Section 120.1 of Title 24, Part 6. The specific recommendations include:

  1. Update the minimum ventilation categories and rates for all Title 24, Part 6 nonresidential occupancy categories
    • The proposed code change will expand Title 24, Part 6 Table 120.1-A – Minimum Ventilation Rates to include and specify ventilation rates for all Title 24, Part 6 occupancy categories, aligning with the rates found in ASHRAE 62.1 Table Minimum Ventilation Rates in Breathing Zone multiplied by 130 percent.
  2. Harmonize with the full ventilation rate procedure (VRP) found in Title 24, Part 4 (ASHRAE 62.1) including the requirements for multiple zone recirculating systems.
    • The proposed code change will adapt the full ventilation rate procedure found in Title 24, Part 4 (ASHRAE 62.1) for calculation of minimum ventilation air supply rates. The ventilation rate procedure calculates outdoor air intake rates based upon the contaminant sources and source emission rates that are typical for that occupancy category. The calculated outdoor air intake rate is intended to be sufficient to dilute and exhaust contaminants from occupants and off-gassing from building materials and furnishings in order to meet the sensory satisfaction of occupants. Hence, the ventilation rate procedure calculates rates that account for the control of both the people-related and building-related sources of contaminants. It is assumed that the people and building area-related source components are additive, and can be scaled proportionally to occupancy and to the space’s floor area, respectively. In addition, the ASHRAE 62.1 Appendix A calculations for multiple-zone recirculating systems will be included.
  3. Revise requirements for natural ventilation.
    • The proposed code change will align the Title 24, Part 6 natural ventilation requirements with those found in Title 24, Part 4 (ASHRAE 62.1). The ASHRAE 62.1 natural ventilation rate requirements include a calculation that establishes the floor area to be ventilated by natural ventilation based on the size and types of openings, and allows a greater floor area of the building to be naturally ventilated without the use of mechanical ventilation than is allowed in the 2016 Title 24, Part 6 requirements.
  4. Revise requirements for outdoor air treatment.
    • The proposed code change will add to Title 24, Part 6 the ASHRAE 62.1 requirements for outdoor air treatment of particulate matter (PM). The proposed code change requires that if the regional and/or local air quality where the building is located is in “non-attainment” (i.e., above threshold concentrations), then outdoor air treatment would be required for the building. For areas that exceed the PM standard, higher minimum efficiency reporting value (MERV) filters or other method of reducing PM in the air stream would be required (MERV 13 for areas exceeding the 2.5 micron (PM2.5) threshold).
  5. Include requirements for exhaust ventilation from Title 24, Part 4 to Title 24, Part 6.
    • The proposed code change will incorporate the requirements for exhaust ventilation found in Title 24, Part 4 Section 403.7 (ASHRAE 62.1 Section 6.5.1) into Title 24, Part 6. This proposed change is primarily an effort to include all ventilation requirements in Title 24, Part 6 for all occupancies regulated by the Energy Commission. Exhaust ventilation requirements are currently included in the California Mechanical Code (Title 24, Part 4) and all other ventilation requirements are in Part 6, which is a source of confusion.

Request for Feedback

The Statewide Utility Team encourages participation in the CASE Report development process through the submission of data—both primary sources and references to existing data. We are requesting data on areas such as energy savings, costs, market impacts, industry practices, barriers to code compliance, etc. from stakeholders. The data will inform the energy savings estimates, cost-effectiveness analysis, compliance and enforcement, and market impacts that will be presented in CASE Reports.

Do you have feedback or data to share? Send us an email at

California Statewide Utility Codes and Standards Program

This program is funded by California utility customers and administered by Pacific Gas and Electric Company, Southern California Edison, San Diego Gas and Electric Company, Southern California Gas Company, Sacramento Municipal District, and Los Angeles Department of Water and Power in preparation for the California Energy Commission’s Codes and Standards Buildings Advocacy.