© Copyright CalCERTS, Inc. 2019
Code Cycle: 2019 Non-Residential Standards
Reference: NRCM 220.127.116.11.1.8
Reference: CalCERTS Non-Residential Training Manual Chapter 5, Section 5
Transfer air is the airflow between adjacent dwelling units in a multifamily building which can be a major contributor to poor indoor air quality in the dwelling units. It is desirable to minimize or eliminate leaks in all of the dwelling enclosures in the building – to compartmentalize the dwellings - to prevent pollutants such as tobacco smoke, pollution generated from food preparation in the kitchen, odors, and other pollutants from being transferred to adjacent dwellings in the building.
Title 24 provides for two compliance paths for mechanical ventilation that improve compartmentalization in multifamily buildings (choose one):
1. Install a balanced ventilation system.
- This may consist of either a single balanced ventilation unit (such as an ERV or HRV), or
- This may consist of separate supply and exhaust fans that operate simultaneously and are controlled to balance the supply and exhaust airflow's, and
- The outdoor ventilation supply air must be filtered (MERV 13 or better).
2. Verify that the dwelling unit leakage is not greater than 0.3 cfm per ft2 of dwelling unit enclosure area using the procedures in RA3.8 (blower door test).
- If the dwelling unit enclosure passes this blower door test, use of continuously operating supply ventilation systems, or continuously operating exhaust ventilation systems in that dwelling is allowed.
For mechanical ventilation system types and verification protocols, see article titled
"2019 HERS Non-Residential Mechanical Ventilation (IAQ) Verification and Form".