Compartmentalization and Balanced Ventilation / Indoor Air Quality (IAQ)

Proposal Description

The 2022 version of Title 24, Part 6 requires multifamily units to comply with either of the following: providing balanced ventilation or meeting a compartmentalization maximum of 0.3 cfm/ft² @50 Pa. This proposal would add a mandatory measure for all new construction multifamily units, with the purpose of protecting IAQ to:

• Use supply-only or balanced ventilation as a whole dwelling unit strategy. Use of exhaust-only ventilation cannot be used for whole dwelling unit ventilation. The proposed language also requires that IAQ system components (i.e., filter and HRV/ERV heat/energy recovery core) be accessible for replacement and maintenance. And
• Require mandatory compartmentalization at a maximum of level of 0.3 cfm/ft² @50Pa.

Local exhaust systems would still be used to meet local exhaust requirements, such as in bathrooms, kitchens, and dryers, and exhaust fans could be used as part of a balanced ventilation approach.

In addition to these changes to the mandatory requirements, the Statewide CASE Team proposes the following changes to the prescriptive requirements and compliance options to promote energy savings:

• Revise the prescriptive requirement in the 2022 Title 24, Part 6 that requires multifamily dwelling units in Climate Zones 1, 2, 4, 11 through 14, and 16 that use the balanced ventilation path to include a heat recovery ventilator (HRV) or energy recovery ventilator (ERV). The proposed change is to prescriptively require all multifamily dwelling units in Climate Zones 1, 2, 4, 11 through 14, and 16 to use balanced ventilation with an HRV or ERV. Multifamily dwelling units in these climate zones that use a performance path could use supply-only ventilation, but the project would need to compensate by exceeding code requirements for energy efficiency with another measure.
• A prescriptive requirement for an FID that serves the outdoor air fan or, where applicable, the HRV/ERV. Projects could instead follow the performance path and incur a penalty in the modeling software that assumes 10 percent lower ventilation fan efficacy, and 10 percent lower SRE for an HRV/ERV.

The proposal does not make changes for additions or alterations.

While most of this CASE Report discusses proposals for multifamily units, the Statewide CASE Team proposes the following requirements for single-family dwelling units.

• Mandatory requirements for IAQ system component accessibility, in which the filter panel, HRV/ERV access panel, and outdoor air inlet must be accessible or within 10 feet of a walking surface. Ventilation systems with an FID would not need to meet the filters, HRV/ERV energy recovery core or outdoor air intake accessibility requirements.
• A prescriptive requirement for an FID that serves the outdoor air fan or, where applicable, the HRV/ERV. Projects could instead follow the performance path and incur a penalty in the modeling software that assumes 10 percent lower ventilation fan efficacy, and 10 percent lower SRE for an HRV/ERV.

Both of these proposed measures for single-family homes align with the proposed requirement for multifamily units, and with 2022-Title 24 Part 6 ACM requirements.