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Multifamily Indoor Air Quality

Measure Description

In order to compare proposed code changes to the current language, the Statewide Case Team refers to the current sections of the 2019 Title 24, Part 6 Standards. The current standard has separate sections for low-rise and high-rise multifamily dwelling units. However, if the proposed code requirement for a unified multifamily section is accepted, the Statewide CASE Team would make one requirement for all multifamily units.  

This Draft CASE Report proposes three sets of requirements, one that is primarily prescriptive but includes a mandatory fan efficacy requirement, and two that are mandatory, for ventilation in all multifamily new construction and additions: 

Heat Recovery Ventilator (HRV)/Energy Recovery Ventilator (ERV)

This proposal would provide cost-effective energy savings by requiring the exhaust stream of a balanced ventilation system to pass through an ERV or HRV so that incoming ventilation air is preheated or precooled.

Kitchen Exhaust Minimum Capture

The purpose of this submeasure is to improve IAQ. As Title 24 evolves to require more envelope tightening, the need for adequate ventilation increases. In particular, 2019 Title 24, Part 6 added the Quality Insulation Installation (QII) procedures to the prescriptive path for low-rise multifamily buildings, and proposed requirements for 2022 Title 24, Part 6 include a version of QII for the prescriptive path for high-rise multifamily buildings. Increased sealing measures in QII reduces infiltration, which provides energy savings, but also heightens the need for adequate ventilation.

Cooking-related pollution carries various health risks, and there is a growing body of research that highlights the health impacts from cooking-related pollution. Cooking over any type of cooktop (natural gas or electric) releases ultra fine and fine particles such as particulate matter 2.5 micrometers or smaller (“PM2.5”), as well as other irritants and potentially harmful gases including formaldehyde, acetaldehyde, acrolein,and polycyclic aromatic hydrocarbons(Singer and Chan 2018).The use of natural gas burners and ovens also releases nitrogen dioxide

The proposed code change will be a mandatory measure that will require a kitchen exhaust system with either a minimum capture efficiency or minimum airflow. The kitchen exhaust system must meet one of the following paths:

  1. A vented range hood with a minimum capture efficiency of 70 percent at nominal installed airflow, or
  2. A vented range hood with a minimum airflow of 250 cubic feet per minute (cfm) at a static pressure of 0.1 inches w.c. or greater, or
  3. A vented downdraft exhaust with a minimum airflow of 300 cubic feet per minute (cfm) at a static pressure of 0.1 inches w.c. or greater, or
  4. (for enclosed kitchens only) Continuous kitchen exhaust at a minimum of five kitchen air changes per hour

The first path is new. The second path doubles the minimum airflow requirement. The third and fourth paths exist in the current requirements and have been retained.

Central Ventilation Duct Sealing

This measure is primarily for energy savings but would also result in IAQ benefits.

The measure would require duct sealing for ventilation ductwork serving multiple dwelling units (referred to as “central ventilation ducts” in this report), and field verification that a sample of ducts meets a maximum leakage requirement. The central ventilation ductwork is typically comprised of a central fan (often located at the rooftop), a central ventilation duct (“shaft”) that runs between floors, horizontal branches to connect the dwelling units to the shaft, and in-unit connection points such as grilles to deliver (for supply) or remove (for exhaust) air from each dwelling unit. The figure below illustrates an example; in this example, there are no horizontal branches.

Relevant Documents

Measure proposals, supporting documents, and other outside references will be made public as they become available.

CASE Reports

Round Two Utility-Sponsored Stakeholder Meeting Materials

Round One Utility-Sponsored Stakeholder Meeting Materials

Submeasure Summaries

Provide Feedback

Draft CASE Report Now Available (Comments accepted until June 12, 2020)

This measure description will be updated as research is developed to support the 2022 code cycle. For questions or suggestions, email Include the measure name in the subject line.


Give Us Your Feedback

The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.

  • Use the form above to provide feedback on this measure.