What ventilation rate procedure applies to dwelling units (405.0 series)?

Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:

• CMC § 62.2 High relevance — show source text

  Vertically attached dwelling units shall not reduce their minimum ventilation rates in accordance with Subsections ii and iii.

  i. Total Required Ventilation Rate [ASHRAE 62.2:4.1.1]. The total required ventilation rate shall be calculated using Equation 150.0-B. (Equation 150.0-B) Q tot = 0.03 A floor + 7.5( N br + 1)

  where:

  Q tot = total required ventilation rate, cfm A floor = dwelling-unit floor area, ft [2]

  N br = number of bedrooms (not to be less than 1) ii. Effective Annual Average Infiltration Rate. The effective annual average infiltration rate shall be determined in accordance with Subsections a and b:

  a. An enclosure leakage rate in cubic feet per minute at 50 Pa (0.2 inch water) ( Q 50 ) shall be determined by either Subsection 1 or Subsection 2 below.

  1. Q 50 shall be calculated based on the conditioned volume of the dwelling unit and a default value for dwelling unit envelope leakage of 2 air changes per hour at 50 PA (0.2 inch water) (2 ACH 50 ) as specified by Equation 150.0-C below. (Equation 150.0-C) Q 50 = V du x 2 ACH 50 /60 min

  168 2025 CALIFORNIA ENERGY CODE

  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

  SINGLE-FAMILY RESIDENTIAL BUILDINGS— MANDATORY FEATURES AND DEVICES

  where:

  Q 50 = leakage rate at 50 Pa. V du = dwelling unit conditioned volume, ft [3] . ACH 50 = air changes per hour at 50 Pa (0.2 inch water). 2. If dwelling unit envelope leakage less than 2 ACH 50 is confirmed by field verification and diagnostic testing, Q 50 shall be calculated according to Equation 150.0-D below, using the value for dwelling unit envelope leakage less than 2 ACH 50 verified by the procedures specified in Reference Residential Appendix RA3.8. (Equation 150.0-D) Q 50 = V du x Verified ACH 50 /60 min

  where:

  Q 50 = leakage rate at 50 Pa. V du = dwelling unit conditioned volume, ft [3] . ACH 50 = air changes per hour at 50 Pa (0.2 inch water). b. The Effective Annual Average Infiltration Rate ( Q inf ) shall be calculated using Equation 150.0-E [ASHRAE 62.2:4.1.2.1]. (Equation 150.0-E) Q inf = 0.052 × Q 50 × wsf × [ H/H r ] [z]

  where:

• CMC § 62.2 High relevance — show source text

  {ASHRAE 62.2:4.1.2.1} E 605.1.3.3 Required Mechanical Ventilation Rate ( Qfan ). If a blower door test has been performed, then a credit for estimated infiltration may be taken for detached dwelling units using either the procedure in Section E 605.1.3.2 or E 605.1.3.4. Attached dwelling units other than horizontally attached shall not be permitted to take an infiltration credit. Horizontally attached dwelling units shall be permitted to use a blower door test result to take this credit, subject to the reduction factor Aext in Equation E 605.1.3.3.

  If this credit is taken, then the Required Mechanical Ventilation Rate ( Qfan ) shall be calculated using Equation E 605.1.3.3: (Equation E 605.1.3.3) Qfan = Qtot – Φ ( Qinf × Aext )

  Where: Qfan = required mechanical ventilation rate, CFM (L/s) Qtot = total required ventilation rate, CFM (L/s) Qinf = infiltration, CFM (L/s) (see ASHRAE 62.2 for exceptions for existing buildings) Aext = 1 for detached dwelling units; otherwise, for horizontally attached dwelling units, the ratio of exterior envelope surface area that is not attached to garages or other dwelling units to total envelope surface area. Φ = 1 for balanced ventilation systems, and Qinf / Qtot otherwise.

  For SI units: 1 cubic foot per minute = 0.4719 L/s

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  ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

  APPENDIX E

  Col1	TABLE E 605.1.3.1 VENTILATION AIR REQUIREMENTS, (cubic foot per minute) [ASHRAE 62.2: TABLE 4-1a]	Col3	Col4	Col5	Col6
  FLOOR AREA (ft2)	BEDROOMS	BEDROOMS	BEDROOMS	BEDROOMS	BEDROOMS
  FLOOR AREA (ft2)	1	2	3	4	5
  <500	30	38	45	53	60
  501-1000	45	53	60	68	75
  1001-1500	60	68	75	83	90
  1501-2000	75	83	90	98	105
  2001-2500	90	98	105	113	120
  2501-3000	105	113	120	128	135
  3001-3500	120	128	135	143	150
  3501-4000	135	143	150	158	165
  4001-4500	150	158	165	173	180
  4501-5000	165	173	180	188	195

  For SI units: 1 square foot = 0.0929 m [2], 1 cubic foot per minute = 0.00047 m [3] /s

• CMC § 62.2 High relevance — show source text

  Exception: Where Qfan, calculated for unbalanced ventilation, is less than or equal to 15 CFM (7 L/s), a dwelling-unit ventilation system is not required.

  [ASHRAE 62.2:4.1.2] E 605.1.3.4 Effective Annual Average Infiltra- tion Rate ( Qinf ) Using a Multipoint Envelope Leakage Test. Effective Annual Average Infiltration Rate ( Qinf ) shall be calculated using the normalized leakage calculated from measurements of envelope leakage using a multipoint test from either ASTM E779 in accordance with Section E 605.1.3.4(A) or CGSB 149.10 in accordance with Section E 605.1.3.4(B). E 605.1.3.4(A) ASTM Procedure. To calculate the effective leak area ( ELA ) from ASTM E779, the leakage area for pressurization and depressurization (using a 0.0006 psi [4 Pa] reference pressure) shall be averaged using Equation E 605.1.3.4(A):

  [Equation E 605.1.3.4(A)]

  ELA = ( Lpress + Ldepress )/ 2

  Where:

  ELA = effective leakage area, ft [2] (m [2] ) Lpress = leakage area from pressurization, ft [2 ] (m [2] ) Ldepress = leakage area from depressurization, ft [2 ] (m [2] )

  For SI units: 1 square foot = 0.0929 m [2]

  E 605.1.3.4(B) CGSB Procedure. To calculate the ELA from CGSB 149.10, the following modifications to the test procedure must be made:

  (1) All vents and intentional openings must be in the same configuration as specified in ASTM E779 (i.e., HVAC dampers and registers should be in the normal operating position; fireplace and

  other dampers should be closed unless they are required for test operation). (2) Height and floor area must be reported consistently with the definitions of this standard. (3) The leakage area as calculated from the CGSB procedure must be converted using Equation E 605.1.3.4(B):

  [Equation E 605.1.3.4(B)] ELA = 0.61 × (0.4) [n] – 0.5 × Lcgsb

  Where:

  n = exponent measured from the CGSB 149.10 Lcgsb = CGSB leakage area as modified above, ft [2 ] (m [2] )

  For SI units: 1 square foot = 0.0929 m [2] E 605.1.3.4(C) Normalized Leakage. Normalized leakage shall be calculated using Equation E 605.1.3.4(C):

  [Equation E 605.1.3.4(C)]

  ELA H z NL = 1000 x x

  Afloor [ Hr ]

  Where:

• CMC § 1.0 High relevance — show source text

  where:

  Q tot = total required ventilation rate, cfm. A floor = dwelling-unit floor area, ft [2] . N br = number of bedrooms (not to be less than 1). b. All dwelling units in a multifamily building shall use the same whole-dwelling unit ventilation system type. The dwelling unit shall comply with Subsections 1 and 2 below.

  1. Balanced or supply ventilation . A balanced or supply ventilation system shall provide the required whole-dwelling-unit ventilation airflow. Balanced systems with heat recovery or energy recovery that serve a single dwelling unit shall have a fan efficacy of ≤1.0 W/cfm; and
  2. Compartmentalization testing. The air leakage rate shall not exceed 0.3 cubic feet per minute at 50 Pa (0.2 inch water) per ft [2] of dwelling unit envelope surface area as confirmed by ECC-Rater field verification and diagnostic testing in accordance with the procedures specified in Reference Appendix RA3.8 or NA2.3 as applicable. In multifamily buildings with four or more habitable stories,

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  MULTIFAMILY BUILDINGS—MANDATORY REQUIREMENTS

  the field verification and diagnostic testing which requires an ECC-Rater may alternatively be performed by a certified Mechanical Acceptance Test Technician according to the requirements specified in Reference Appendix NA1.9. v. Multifamily building central ventilation system airflow rate tolerance. Multifamily building central ventilation systems that serve multiple dwelling units shall have airflow rates in each dwelling unit served that meet or exceed a design ventilation airflow rate specification. a. Designers shall specify a design ventilation airflow rate for each dwelling unit that is equal to or greater than the rate specified by Equation 160.2-B. b. The design ventilation airflow rate for each dwelling unit shall be stated on the building design plans approved by the enforcement agency. c. Airflow in each dwelling unit shall be no more than 20 percent greater than the specified design ventilation airflow rate. Ventilation systems shall utilize mechanical or software airflow control means to ensure each of the dwelling-unit airflows can be maintained at the design ventilation airflow within this tolerance at all times. System airflow control-means may include but are not limited to constant air regulation devices, orifice plates and variable speed central fans. vi. Local mechanical exhaust. A local mechanical exhaust system shall be installed in each kitchen and bathroom. Systems shall be rated for airflow in accordance with ASHRAE 62.2 Section 7.1. a. Nonenclosed kitchens shall have a demand-controlled mechanical exhaust system meeting the requirements of Section 160.2(b)2Avic. b. Enclosed kitchens and all bathrooms shall have either one of the following options 1 or 2:

  1. A demand-controlled mechanical exhaust system meeting the requirements of Section 160.2(b)2Avic; or
  2. A continuous mechanical exhaust system meeting the requirements of Section 160.2(b)2Avid. c. Demand-controlled mechanical exhaust. A local mechanical exhaust system shall be designed to be operated as needed.
  3. Control and operation. Demand-controlled mechanical exhaust systems shall be provided with at least one of the following controls: A. A readily accessible occupant-controlled ON-OFF control. B. An automatic control that does not impede occupant ON control.
  4. **Ventilation rate and capture efficiency.
• CMC § 62.2 High relevance — show source text

  (1) The building has no mechanical cooling and is in zone 1 or 2 of the climate zone map.

  (2) The building is thermally conditioned for human occupancy for less than 876 hours per year. [ASHRAE 62.2:4.1.1] E 605.1.3.2 Effective Annual Average Infiltra- tion Rate ( Qinf ) Using a Single-Point Enve- lope Leakage Test. Effective Annual Average

  Infiltration Rate ( Qinf ) shall be calculated using a single-point test at 0.007 psi (50 Pa). The Effective Annual Average Infiltration Rate ( Qinf ) shall be calculated using Equation 605.1.3.2:

  (Equation E 605.1.3.2) Qinf = 0.052 × Q 50 × wsf × ( H/Hr ) [z]

  Where: Qinf = estimated infiltration rate, CFM (L/s). Q50 = leakage rate at 0.007 psi (50 Pa) depressurization or pressurization, CFM (L/s). wsf = weather and shielding factor from ASHRAE 62.2.

  H = vertical distance between the lowest and highest above-grade points within the pressure boundary, ft (m). Hr = reference height, 8.2 ft (2.5 m). z = 0.4 for the purpose of calculating the Effective Annual Average Infiltration Rate.

  For SI units: 1 foot = 0.3048 m, 1 cubic foot per minute =

  0.4719 L/s

  {ASHRAE 62.2:4.1.2.1} E 605.1.3.3 Required Mechanical Ventilation Rate ( Qfan ). If a blower door test has been performed, then a credit for estimated infiltration may be taken for detached dwelling units using either the procedure in Section E 605.1.3.2 or E 605.1.3.4. Attached dwelling units other than horizontally attached shall not be permitted to take an infiltration credit. Horizontally attached dwelling units shall be permitted to use a blower door test result to take this credit, subject to the reduction factor Aext in Equation E 605.1.3.3.

  If this credit is taken, then the Required Mechanical Ventilation Rate ( Qfan ) shall be calculated using Equation E 605.1.3.3: (Equation E 605.1.3.3) Qfan = Qtot – Φ ( Qinf × Aext )

  Where: Qfan = required mechanical ventilation rate, CFM (L/s) Qtot = total required ventilation rate, CFM (L/s) Qinf = infiltration, CFM (L/s) (see ASHRAE 62.2 for exceptions for existing buildings) Aext = 1 for detached dwelling units; otherwise, for horizontally attached dwelling units, the ratio of exterior envelope surface area that is not attached to garages or other dwelling units to total envelope surface area. Φ = 1 for balanced ventilation systems, and Qinf / Qtot otherwise.

  For SI units: 1 cubic foot per minute = 0.4719 L/s

  476 2025 CALIFORNIA MECHANICAL CODE

• CMC § 605.1.3 High relevance — show source text

  E 605.1.3 Dwelling Unit Ventilation. A mechanical exhaust system, supply system, or combination thereof shall be designed and provided with the capacity to deliver outdoor air ventilation to the whole dwelling unit at a continuous rate not less than that specified in Section E 605.1.3.1 through Section E 605.1.3.5. [ASHRAE 62.2:4.1]

  E 605.1.3.1 Total Ventilation Rate. The total required ventilation rate ( Qtot ) shall be as specified in Table E 605.1.3.1 or, alternatively, calculated using Equation E 605.1.3.1.

  (Equation E 605.1.3.1) Qtot = 0.03 Afloor + 7.5( Nbr + 1)

  Where:

  Qtot = total required ventilation rate, CFM Afloor = dwelling unit floor area, ft [2] Nbr = number of bedrooms (not to be less than one)

  For SI units: 1 cubic foot per minute = 0.00047 m [3] /s, 1 cubic foot

  per minute = 0.4719 L/s

  Exceptions: Dwelling-unit mechanical ventilation systems shall not be required where the Authority Having Jurisdiction determines that window operation is a locally permissible method of providing ventilation and provided one or more of the following conditions is met:

  (1) The building has no mechanical cooling and is in zone 1 or 2 of the climate zone map.

  (2) The building is thermally conditioned for human occupancy for less than 876 hours per year. [ASHRAE 62.2:4.1.1] E 605.1.3.2 Effective Annual Average Infiltra- tion Rate ( Qinf ) Using a Single-Point Enve- lope Leakage Test. Effective Annual Average

  Infiltration Rate ( Qinf ) shall be calculated using a single-point test at 0.007 psi (50 Pa). The Effective Annual Average Infiltration Rate ( Qinf ) shall be calculated using Equation 605.1.3.2:

  (Equation E 605.1.3.2) Qinf = 0.052 × Q 50 × wsf × ( H/Hr ) [z]

  Where: Qinf = estimated infiltration rate, CFM (L/s). Q50 = leakage rate at 0.007 psi (50 Pa) depressurization or pressurization, CFM (L/s). wsf = weather and shielding factor from ASHRAE 62.2.

  H = vertical distance between the lowest and highest above-grade points within the pressure boundary, ft (m). Hr = reference height, 8.2 ft (2.5 m). z = 0.4 for the purpose of calculating the Effective Annual Average Infiltration Rate.

  For SI units: 1 foot = 0.3048 m, 1 cubic foot per minute =

  0.4719 L/s

• CMC § 38.22 High relevance — show source text

  Airport|38.22|–122.28|California| |724957|0.49|Santa Rosa (AWOS)|38.52|–122.82|California| |725845|0.44|Blue Canyon AP|39.30|–120.72|California| |725846|0.66|Truckee–Tahoe|39.32|–120.13|California| |725847|0.64|South Lake Tahoe|38.90|–120.00|California| |725905|0.47|Ukiah Municipal AP|39.13|–123.20|California| |725910|0.50|Red Bluff Municipal Arpt|40.15|–122.25|California| |725920|0.47|Redding Municipal Arpt|40.52|–122.32|California| |725945|0.56|Arcata Airport|40.98|–124.10|California| |725946|0.60|Crescent City Faa Ai|41.78|–124.23|California| |725955|0.55|Montague Siskiyou County AP|41.78|–122.47|California| |725958|0.59|Alturas|41.50|–120.53|California| |745090|0.45|Mountain View Moffett Fld NAS|37.40|–122.05|California| |745160|0.67|Travis Field AFB|38.27|–121.93|California| |746120|0.52|China Lake Naf|35.68|–117.68|California| |747020|0.50|Lemoore Reeves NAS|36.33|–119.95|California| |747185|0.46|Imperial|32.83|–115.58|California| |747187|0.46|Palm Springs Thermal AP|33.63|–116.17|California| |747188|0.48|Blythe Riverside Co Arpt|33.62|–114.72|California|

  iii. Required Mechanical Ventilation Rate [ASHRAE 62.2:4.1.2] The Required Mechanical Ventilation Rate ( Q fan ) shall be calculated using Equation 150.0-F. (Equation 150.0-F) Q fan = Q tot – Φ ( Q inf × A ext )

  where:

  Q fan = required mechanical ventilation rate, cfm (L/s). Q tot = total required ventilation rate, cfm (L/s) from Equation 150.0-B. Q inf = effective annual average infiltration rate, cfm (L/s) from Equation 150.0-E. A ext = 1 for single-family detached homes, or the ratio of exterior envelope surface area that is not attached to garages or other dwelling units to total envelope surface area for attached dwelling units not sharing ceilings or floors with other dwelling units, occupiable spaces, public garages, or commercial spaces. Φ = 1 for balanced ventilation systems and Q inf /Q tot otherwise. iv. **Requirements for balanced and supply-only ventilation systems.

• CMC § 605.0 High relevance — show source text

  E 605.0 Indoor Air Quality for Low-Rise Residential. E 605.1 General. Rooms or occupied spaces within singlefamily homes and multifamily structures of three stories or less above grade shall be designed to have ventilation (outdoor) air for occupants in accordance with Section E 605.1.1 through Section E 605.1.3.2, or the applicable local code.

  2025 CALIFORNIA MECHANICAL CODE 475

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  APPENDIX E

  E 605.1.1 Natural Ventilation. Naturally ventilated spaces shall be permanently open to and within 20 feet (6096 mm) of operable wall or roof openings to the outdoors, the openable area of which is not less than 5 percent of the conditioned floor area of the naturally ventilated space. Where openings are covered with louvers or otherwise obstructed, openable area shall be based on the free unobstructed area through the opening. E 605.1.1.1 Access to Operable Openings. The means to open required operable openings shall be readily accessible to building occupants where the space is occupied.

  E 605.1.2 Mechanical Ventilation. Each space that is not naturally ventilated in accordance with Section E 605.1.1 shall be ventilated with a mechanical system capable of providing an outdoor air rate not less than 15 ft [3] /min (0.007 m [3] /s) per person times the expected number of occupants. Mechanical ventilation shall comply with this code.

  E 605.1.3 Dwelling Unit Ventilation. A mechanical exhaust system, supply system, or combination thereof shall be designed and provided with the capacity to deliver outdoor air ventilation to the whole dwelling unit at a continuous rate not less than that specified in Section E 605.1.3.1 through Section E 605.1.3.5. [ASHRAE 62.2:4.1]

  E 605.1.3.1 Total Ventilation Rate. The total required ventilation rate ( Qtot ) shall be as specified in Table E 605.1.3.1 or, alternatively, calculated using Equation E 605.1.3.1.

  (Equation E 605.1.3.1) Qtot = 0.03 Afloor + 7.5( Nbr + 1)

  Where:

  Qtot = total required ventilation rate, CFM Afloor = dwelling unit floor area, ft [2] Nbr = number of bedrooms (not to be less than one)

  For SI units: 1 cubic foot per minute = 0.00047 m [3] /s, 1 cubic foot

  per minute = 0.4719 L/s

  Exceptions: Dwelling-unit mechanical ventilation systems shall not be required where the Authority Having Jurisdiction determines that window operation is a locally permissible method of providing ventilation and provided one or more of the following conditions is met:

  (1) The building has no mechanical cooling and is in zone 1 or 2 of the climate zone map.

• CMC § 180.2 High relevance — show source text

  A. Small duct high velocity systems shall demonstrate a minimum system airflow rate greater than or equal to 250 cfm per ton of nominal cooling capacity; or

  2025 CALIFORNIA ENERGY CODE 277

  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

  MULTIFAMILY BUILDINGS—ADDITIONS, ALTERATIONS AND REPAIRS TO EXISTING MULTIFAMILY BUILDINGS

  B. All other air-cooled air conditioner or air-source heat pump systems shall demonstrate a minimum system airflow rate greater than or equal to 300 cfm per ton of nominal cooling capacity. Exception 1 to Section 180.2(b)2AivbI : Systems unable to comply with the minimum airflow rate requirement shall demonstrate compliance using the procedures in Section RA3.3.3.1.5, and the system's thermostat shall conform to the specifications in Section 110.12. Exception 2 to Section 180.2(b)2AivbI: Entirely new or complete replacement space-conditioning systems, as specified by Section 180.2(b)2Ai, without zoning dampers may comply with the minimum airflow rate by meeting the applicable requirements in Table 160.3-A or 160.3-B as confirmed by field verification and diagnostic testing in accordance with the procedures in Reference Residential Appendix Sections RA3.1.4.4 and RA3.1.4.5. The design clean-filter pressure drop requirements of Section 160.2(a)1C for the system air filter device(s) shall conform to the requirements given in Tables 160.3-A and 160.3-B.

  II. The installer shall charge the system according to manufacturer’s specifications. Refrigerant charge shall be verified according to one of the following options, as applicable. A. The installer and rater shall perform the standard charge verification procedure as specified in Reference Residential Appendix Section RA3.2.2, or an approved alternative procedure as specified in Section RA1; or B. The installer shall perform the weigh-in charging procedure as specified by Reference Residential Appendix Section RA3.2.3.1, provided the system is of a type that can be verified using the RA3.2.2 standard charge verification procedure and RA3.3 airflow rate verification procedure or approved alternatives in RA1. The ECC-Rater shall verify the charge using RA3.2.2 and RA3.3 or approved alternatives in RA1. Exception 1 to Section 180.2(b)2AivbII : When the outdoor temperature is less than 55°F and the installer utilizes the weigh-in charging procedure in Reference Residential Appendix Section RA3.2.3.1 to demonstrate compliance, the installer may elect to utilize the verification procedure in Reference Residential Appendix Section RA3.2.3.2. If the verification procedure in Section RA3.2.3.2 is used for compliance, the system's thermostat shall conform to the specifications in Section 110.12. Ducted systems shall comply with the minimum system airflow rate requirements in Section 180.2(b)2AivbI. Exception 2 to Section 180.2(b)2Aivb: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. v. Altered space-heating system. Altered or replacement space-heating systems shall not use electric resistance as the primary heat source.

• CMC § 160.2 High relevance — show source text

  If the outdoor airflow for the CFI ventilation system is fan-powered, then the outdoor air fan shall not operate when the required motorized damper(s) on the outdoor air ventilation duct(s) is closed.

  d. Variable ventilation. CFI ventilation systems shall incorporate controls that track outdoor air ventilation run time, and either open or close the required motorized damper(s) depending on whether or not outdoor air ventilation is required for compliance with Section 160.2(b)2Aiv. During periods when comfort conditioning is not called for by the space-conditioning thermostat, the CFI ventilation system controls shall operate the space-conditioning system central fan and outdoor air damper(s) when necessary to ensure compliance with the minimum outdoor air ventilation required by Section 160.2(b)2Aiv in accordance with applicable variable mechanical ventilation methods specified in ASHRAE 62.2 Section 4.5.

  iii. Air filtration. Air filtration shall conform to the specifications in Section 160.2(b)1. Compliance with ASHRAE 62.2 Sections 6.7 (Minimum Filtration) and 6.7.1 (Filter Pressure Drop) shall not be required. iv. Whole-dwelling unit mechanical ventilation . Multifamily attached dwelling units shall comply with Subsections a and b below.

  a. Mechanical ventilation airflow shall be provided at rates greater than or equal to the value determined in accordance with Equation 160.2-B. Total Required Ventilation Rate [ASHRAE 62.2:4.1.1]: (Equation 160.2-B) Q tot = 0.03 A floor + 7.5( N br + 1)

  where:

  Q tot = total required ventilation rate, cfm. A floor = dwelling-unit floor area, ft [2] . N br = number of bedrooms (not to be less than 1). b. All dwelling units in a multifamily building shall use the same whole-dwelling unit ventilation system type. The dwelling unit shall comply with Subsections 1 and 2 below.

  1. Balanced or supply ventilation . A balanced or supply ventilation system shall provide the required whole-dwelling-unit ventilation airflow. Balanced systems with heat recovery or energy recovery that serve a single dwelling unit shall have a fan efficacy of ≤1.0 W/cfm; and
  2. Compartmentalization testing. The air leakage rate shall not exceed 0.3 cubic feet per minute at 50 Pa (0.2 inch water) per ft [2] of dwelling unit envelope surface area as confirmed by ECC-Rater field verification and diagnostic testing in accordance with the procedures specified in Reference Appendix RA3.8 or NA2.3 as applicable. In multifamily buildings with four or more habitable stories,

  202 2025 CALIFORNIA ENERGY CODE

  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

  MULTIFAMILY BUILDINGS—MANDATORY REQUIREMENTS

  the field verification and diagnostic testing which requires an ECC-Rater may alternatively be performed by a certified Mechanical Acceptance Test Technician according to the requirements specified in Reference Appendix NA1.9. v. Multifamily building central ventilation system airflow rate tolerance. Multifamily building central ventilation systems that serve multiple dwelling units shall have airflow rates in each dwelling unit served that meet or exceed a design ventilation airflow rate specification.

• CMC § 35.68 High relevance — show source text

  52|China Lake Naf|35.68|–117.68|California| |747020|0.50|Lemoore Reeves NAS|36.33|–119.95|California| |747185|0.46|Imperial|32.83|–115.58|California| |747187|0.46|Palm Springs Thermal AP|33.63|–116.17|California| |747188|0.48|Blythe Riverside Co Arpt|33.62|–114.72|California|

  iii. Required Mechanical Ventilation Rate [ASHRAE 62.2:4.1.2] The Required Mechanical Ventilation Rate ( Q fan ) shall be calculated using Equation 150.0-F. (Equation 150.0-F) Q fan = Q tot – Φ ( Q inf × A ext )

  where:

  Q fan = required mechanical ventilation rate, cfm (L/s). Q tot = total required ventilation rate, cfm (L/s) from Equation 150.0-B. Q inf = effective annual average infiltration rate, cfm (L/s) from Equation 150.0-E. A ext = 1 for single-family detached homes, or the ratio of exterior envelope surface area that is not attached to garages or other dwelling units to total envelope surface area for attached dwelling units not sharing ceilings or floors with other dwelling units, occupiable spaces, public garages, or commercial spaces. Φ = 1 for balanced ventilation systems and Q inf /Q tot otherwise. iv. Requirements for balanced and supply-only ventilation systems. a. IAQ filter and HRV/ERV accessibility: System air filters and HRV/ERV heat/energy recovery cores shall be located such that they are accessible for service from within occupiable spaces, basements, garages, balconies, and mechanical closets. Filters and heat/energy cores behind access panels, access doors, or grilles located not more than 10 feet above a walking surface inside a space specified above comply with this requirement. Exception to Section 150.0(o)1Civa: Systems that require servicing from inside the attic shall have the following:

  1. A fault indicator display (FID) meeting the requirements of Reference Appendix JA17.
  2. An attic access door located in a wall or, where attic access is provided through a ceiling, an attic access hatch that includes an integrated ladder.
  3. A walkway from the attic access door to the HRV/ERV. b. IAQ system component accessibility: Fans, motors, heat exchangers, filters and recovery cores shall meet all applicable requirements of California Mechanical Code Section 304.0 accessibility for service. c. Outdoor air intake design: Outdoor air intakes shall comply with California Mechanical Code Section 402.4.1.

  d. Outdoor air intake location and accessibility: To provide access for cleaning, outdoor air intakes shall be accessible. Air intakes located not more than 10 feet above a walking surface comply with this requirement. If located on roofs, they shall meet the requirements of California Mechanical Code Section 304.3.1.

  Exception to Section 150.0(o)1Civd: Outdoor air intake serving equipment with an FID meeting the requirements of Reference Appendix JA17.

  2025 CALIFORNIA ENERGY CODE 171

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• CMC § 110.0 High relevance — show source text

  B. Space-conditioning and ventilation systems. All space heating and space cooling equipment serving dwelling units shall comply with minimum Appliance Efficiency Regulations as specified in Sections 110.0 through 110.2 and meet all applicable requirements of Sections 160.3(b) and 170.2(c)2. i. Refrigerant charge—systems serving individual dwelling units. When refrigerant charge verification or fault indicator display is shown as required by Table 170.2-K, the system shall comply with either Section 170.2(c), 170.2(c)3Bia or 170.2(c)3Bib:

  a. Air-cooled air conditioners and air-source heat pumps, including but not limited to ducted split systems, ducted packaged systems, small duct high velocity systems and mini-split systems, shall comply with Subsections I, II and III, unless the system is of a type that cannot be verified using the specified procedures: I. Have measurement access holes (MAH) installed according to the specifications in Reference Residential Appendix Section RA3.2.2.3; and II. System airflow rate in accordance with Subsection A or B below shall be confirmed through field verification and diagnostic testing in accordance with all applicable procedures specified in Reference Residential Appendix Section RA3.3 or an approved alternative procedure as specified by RA1; and A. For small duct high velocity systems, the system airflow rate shall be greater than or equal to 250 cfm per ton; or B. For all other air-cooled air conditioner or air-source heat pump systems, the system airflow rate shall be greater than or equal to 350 cfm per ton. III. The installer shall charge the system according to manufacturer’s specifications. Refrigerant charge shall be verified according to one of the following options, as applicable: A. The installer and rater shall perform the standard charge procedure as specified by Reference Residential Appendix Section RA3.2.2 or an approved alternative procedure as specified by RA1; or B. The installer shall perform the weigh-in charging procedure as specified by Reference Residential Appendix Section RA3.2.3.1, provided the system is of a type that can be verified using

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  MULTIFAMILY BUILDINGS—PERFORMANCE AND PRESCRIPTIVE COMPLIANCE APPROACHES

  the RA3.2.2 standard charge verification procedure and RA3.3 airflow rate verification procedure or approved alternatives in RA1. The ECC-Rater shall verify the charge using RA3.2.2 and RA3.3 or approved alternatives in RA1. Exception to Section 170.2(c)3BiaI: Systems that cannot conform to the specifications for hole location in Reference Residential Appendix Figure RA3.2-1 shall not be required to provide holes as described in Figure RA3.2-1. Exception to Section 170.2(c)3BiaII: Standard ducted systems without zoning dampers may comply with the minimum airflow rate by meeting the applicable requirements in Table 160.3-A and Table 160.3-B as confirmed by field verification and diagnostic testing in accordance with the procedures in Reference Residential Appendix Sections RA3.1.4.4 and RA3.1.4.5. The design clean-filter pressure drop requirements of Section 160.2(b)1D for the system air filter device(s) shall conform to the requirements given in Table 160.3-A and Table 160.3-B.

• CMC § 150.0 High relevance — show source text

  ii. Outdoor air damper(s) . A motorized damper(s) shall be installed on the connected ventilation duct(s) of CFI systems that prevents all airflow into or out of the space-conditioning duct system when the damper(s) is closed.

  iii. Damper control . The required motorized damper(s) shall be controlled to be in an opened position when outdoor air ventilation is required for compliance, and shall be in the closed position when ventilation air is not required. The damper(s) shall be closed whenever the space-conditioning system air handling unit is not operating. If the outdoor airflow for the CFI ventilation system is fan-powered, then the outdoor air fan shall not operate when the required motorized damper(s) on the outdoor air ventilation duct(s) is closed. iv. Variable ventilation. CFI ventilation systems shall incorporate controls that track outdoor air ventilation run time, and either open or close the required motorized damper(s) depending on whether or not outdoor air ventilation is required for compliance with Section 150.0(o)1C. During periods when comfort conditioning is not called for by the space-conditioning thermostat, the CFI ventilation system controls shall operate the spaceconditioning system central fan and outdoor air damper(s) when necessary to ensure compliance with the minimum outdoor air ventilation required by Section 150.0(o) in accordance with applicable variable mechanical ventilation methods specified in ASHRAE 62.2 Section 4.5. C. Whole-dwelling unit mechanical ventilation for single-family dwellings. Single-family dwellings shall have mechanical ventilation as specified in Subsections i and iv. Single-family detached dwelling units and attached dwelling units not sharing ceilings or floors with other dwelling units, occupiable spaces, public garages, or commercial spaces may reduce their required mechanical ventilation rates in accordance with Subsections ii and iii. Vertically attached dwelling units shall not reduce their minimum ventilation rates in accordance with Subsections ii and iii.

  i. Total Required Ventilation Rate [ASHRAE 62.2:4.1.1]. The total required ventilation rate shall be calculated using Equation 150.0-B. (Equation 150.0-B) Q tot = 0.03 A floor + 7.5( N br + 1)

  where:

  Q tot = total required ventilation rate, cfm A floor = dwelling-unit floor area, ft [2]

  N br = number of bedrooms (not to be less than 1) ii. Effective Annual Average Infiltration Rate. The effective annual average infiltration rate shall be determined in accordance with Subsections a and b:

  a. An enclosure leakage rate in cubic feet per minute at 50 Pa (0.2 inch water) ( Q 50 ) shall be determined by either Subsection 1 or Subsection 2 below.

  1. Q 50 shall be calculated based on the conditioned volume of the dwelling unit and a default value for dwelling unit envelope leakage of 2 air changes per hour at 50 PA (0.2 inch water) (2 ACH 50 ) as specified by Equation 150.0-C below. (Equation 150.0-C) Q 50 = V du x 2 ACH 50 /60 min

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• CMC § 150.1 High relevance — show source text

  Exception to Section 150.1(c)7Aib: Standard ducted systems without zoning dampers may comply with the minimum airflow rate by meeting the applicable requirements in Table 150.0-B or 150.0-C as confirmed by field verification and diagnostic testing in accordance with the procedures in Reference Residential Appendix Section RA3.1.4.4 and RA3.1.4.5. The design clean-filter pressure drop requirements of Section 150.0(m)12D for the system air filter device(s) shall conform to the requirements given in Tables 150.0-B and 150.0-C.

  c. The installer shall charge the system according to manufacturer’s specifications. Refrigerant charge shall be verified according to one of the following options, as applicable: I. The installer and rater shall perform the standard charge procedure as specified by Reference Residential Appendix Section RA3.2.2, or an approved alternative procedure as specified by Section RA1; or

  II. The installer shall perform the weigh-in charging procedure as specified by Reference Residential Appendix Section RA3.2.3.1 provided the system is of a type that can be verified using the Section RA3.2.2 standard charge verification procedure and Section RA3.3 airflow rate verification procedure or approved alternatives in Section RA1. The ECC-Rater shall verify the charge using Sections RA3.2.2 and RA3.3 or approved alternatives in Section RA1. Exception 1 to Section 150.1(c)7Aic: When the outdoor temperature is less than 55°F and the installer utilizes the weigh-in charging procedure in Reference Residential Appendix Section RA3.2.3.1 to verify the refrigerant charge, the installer may elect to utilize the verification procedure in Reference Residential Appendix Section RA3.2.3.2. If the verification procedure in Section RA3.2.3.2 is used for compliance, the system's thermostat shall conform to the specifications in Section 110.12. Ducted systems shall comply with minimum system airflow rate requirement in Section 150.1(c)7Aib. ii. Air-cooled air conditioners and air-source heat pumps, including but not limited to ducted split systems, ducted packaged systems, small duct high-velocity systems and mini-split systems, which are of a type that cannot be verified using the specified procedures, with the requirements of Section 150.1(c)7Ai shall comply with Subsections a and b, as applicable. a. The installer shall confirm the refrigerant charge using the weigh-in charging procedure specified in Reference Residential Appendix Section RA3.2.3.1, as verified by an ECC-Rater according to the procedures specified in Reference Residential Appendix Section RA3.2.3.2.; and b. Systems that utilize forced air ducts shall comply with the minimum system airflow rate requirement in Section 150.1(c)7Aib provided the system is of a type that can be verified using the procedures in Section RA3.3 or an approved alternative procedure in Section RA1.

• CMC § 403.3 High relevance — show source text

  403.3 Single-Zone Systems. For ventilation systems where one or more air handlers supply a mixture of outdoor air and recirculated air to only one ventilation zone, the outdoor air intake flow ( Vot ) shall be determined in accordance with Equation 403.3. [ASHRAE 62.1:6.2.2]

  Vot = Voz (Equation 403.3)

  403.4 One Hundred Percent Outdoor Air Systems. For ventilation systems where one or more air handlers supply only outdoor air to one or more ventilation zones, the outdoor air intake flow ( Vot ) shall be determined in accordance with Equation 403.4. [ASHRAE 62.1:6.2.3]

  Vot = ∑ all zones Voz (Equation 403.4)

  403.5 Multiple-Zone Recirculating Systems. For ventilation systems where one or more air handlers supply a mixture of outdoor air and recirculated air to more than one ventilation zone, the outdoor air intake flow ( Vot ) shall be determined in accordance with Section 403.5.1 through Section 403.5.2. [ASHRAE 62.1:6.2.4]

  403.5.1 Uncorrected Outdoor Air Intake. The uncorrected outdoor air intake ( Vou ) flow shall be determined in accordance with Equation 403.5.1. [ASHRAE 62.1:6.2.4.1]

  (Equation 403.5.1) Vou = D ∑ all zones ( Rp•Pz ) + ∑ all zones ( Ra•Az )

  403.5.1.1 Occupant Diversity. The occupant diversity ratio ( D) shall be determined in accordance with Equation 403.5.1.1 to account for variations in population within the ventilation zones served by the system.

  (Equation 403.5.1.1) D = Ps / ∑ all zones Pz

  Where the system population ( Ps ) is the total population in the area served by the system.

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  VENTILATION AIR

  Exception: Alternative methods to account for occupant diversity shall be permitted, provided that the resulting ( Vou ) value is not less than that determined in accordance with Equation 403.5.1.

  [ASHRAE 62.1:6.2.4.1.1]

  403.5.1.2 System Ventilation Efficiency. The system ventilation efficiency ( Ev ) shall be determined in accordance with Section 403.5.1.3 for the

  simplified procedure or Section 404.0 for the alternate procedure. These procedures also establish zone minimum primary airflow rates for VAV systems.

  [ASHRAE 62.1:6.2.4.2]

  403.5.1.3 Simplified Procedure for System Ventilation Efficiency. System ventilation efficiency ( Ev ) shall be determined in accordance with Equation 403.5.1.3(1) or Equation 403.5.1.3(2).

• CMC § 0.0929 High relevance — show source text

  For SI units: 1 square foot = 0.0929 m [2]

  E 605.1.3.4(B) CGSB Procedure. To calculate the ELA from CGSB 149.10, the following modifications to the test procedure must be made:

  (1) All vents and intentional openings must be in the same configuration as specified in ASTM E779 (i.e., HVAC dampers and registers should be in the normal operating position; fireplace and

  other dampers should be closed unless they are required for test operation). (2) Height and floor area must be reported consistently with the definitions of this standard. (3) The leakage area as calculated from the CGSB procedure must be converted using Equation E 605.1.3.4(B):

  [Equation E 605.1.3.4(B)] ELA = 0.61 × (0.4) [n] – 0.5 × Lcgsb

  Where:

  n = exponent measured from the CGSB 149.10 Lcgsb = CGSB leakage area as modified above, ft [2 ] (m [2] )

  For SI units: 1 square foot = 0.0929 m [2] E 605.1.3.4(C) Normalized Leakage. Normalized leakage shall be calculated using Equation E 605.1.3.4(C):

  [Equation E 605.1.3.4(C)]

  ELA H z NL = 1000 x x

  Afloor [ Hr ]

  Where:

  NL = normalized leakage ELA = effective leakage area, ft [2] (m [2] ) Afloor = floor area of residence, ft [2] (m [2] ) H = vertical distance between the lowest and highest above-grade points within the pressure boundary, ft (m) Hr = reference height, 8.2 ft (2.5 m) z = 0.4 for the purpose of calculating the Effective Annual Infiltration Rate

  For SI units: 1 foot = 0.3048 m, 1 square foot = 0.0929 m [2]

  ELA H z NL = 1000 x x [ Hr ]

  Afloor Hr

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  APPENDIX E

  Exception: For multifamily dwelling units, the manual ON-OFF control shall not be required to be readily accessible. [ASHRAE 62.2:4.4, 4.4.1] E 605.1.6.1 Operation. The system shall be operated as designed. [ASHRAE 62.2:4.4.2] E 605.1.7 Variable Mechanical Ventilation. Dwellingunit mechanical ventilation systems designed to provide variable ventilation shall comply with Section E 605.1.7.1, Section E 605.1.7.2, or Section E 605.1.7.3. Section E 605.1.7.2 and Section E 605.1.7.3 also require compliance with ASHRAE 62.2 and require verification with supporting documentation from the manufacturer, designer, or specifier of the ventilation control system that the system meets the requirements of these sections.

• CMC § 150.2 High relevance — show source text

  a. Minimum system airflow rate shall comply with the applicable Subsection I or II below as confirmed through field verification and diagnostic testing in accordance with the procedures specified in Reference Residential Appendix Section RA3.3 or an approved alternative procedure as specified in Section RA1.

  1. Small duct high-velocity systems shall demonstrate a minimum system airflow rate greater than or equal to 250 cfm per ton of nominal cooling capacity; or
  2. All other air-cooled air conditioner or air-source heat pump systems shall demonstrate a minimum system airflow rate greater than or equal to 300 cfm per ton of nominal cooling capacity; and Exception 1 to Section 150.2(b)1Fiia: Systems unable to comply with the minimum airflow rate requirement shall demonstrate compliance using the procedures in Section RA3.3.3.1.5; and the system’s thermostat shall conform to the specifications in Section 110.12. Exception 2 to Section 150.2(b)1Fiia: Entirely new or complete replacement space-conditioning systems, as specified by Section 150.2(b)1C, without zoning dampers may comply with the minimum airflow rate by meeting the applicable requirements in Table 150.0-B or 150.0-C as confirmed by field verification and diagnostic testing in accordance with the procedures in Reference Residential Appendix Section RA3.1.4.4 and RA3.1.4.5. The design clean-filter pressure drop requirements of Section 150.0(m)12C for the system air filter device(s) shall conform to the requirements given in Tables 150.0-B and 150.0-C. b. The installer shall charge the system according to manufacturer’s specifications. Refrigerant charge shall be verified according to one of the following options, as applicable. I. The installer and rater shall perform the standard charge verification procedure as specified in Reference Residential Appendix Section RA3.2.2, or an approved alternative procedure as specified in Section RA1; or

  II. The installer shall perform the weigh-in charging procedure as specified by Reference Residential Appendix Section RA3.2.3.1, provided the system is of a type that can be verified using the RA3.2.2 standard charge verification procedure and RA3.3 airflow rate verification procedure or approved alternatives in RA1. The ECC-Rater shall verify the charge using RA3.2.2 and RA3.3 or approved alternatives in RA1.

  Exception to Section 150.2(b)1Fiib: When the outdoor temperature is less than 55°F and the installer utilizes the weigh-in charging procedure in Reference Residential Appendix Section RA3.2.3.1 to demonstrate compliance, the installer may elect to utilize the verification procedure in Reference Residential Appendix Section RA3.2.3.2. If the verification procedure in Section RA3.2.3.2 is used for compliance, the system’s thermostat shall conform to the specifications in Section 110.12. Ducted systems shall comply with the minimum system airflow rate requirements in Section 150.2(b)1Fiia. iii. Air-cooled air conditioners in Climate Zones 2 and 8 through 15 and air-source heat pumps in all climate zones, including but not limited to ducted split systems, ducted package systems, small duct high-velocity, and minisplit systems, which are of a type that cannot comply with the requirements of 150.2(b)1Fiib shall comply with Subsections a and b, as applicable.

• CMC § 1.8 High relevance — show source text

  For SI units: °C = (°F-32)/1.8

  • NR = Not Required

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  APPENDIX E

  (1) Unit controls shall have the mechanical cooling capacity control interlocked with the air economizer controls such that the outdoor air damper is at the 100 percent open position when mechanical cooling is on, and the outdoor air damper does not begin to close to prevent coil freezing due to minimum compressor run time until the leaving air temperature is less than 45°F (7°C).

  (2) DX units with a rated capacity no less than 65 000 Btu/h (19 kW) that control the capacity of the mechanical cooling directly based on occupied space temperature shall have not less than two stages of mechanical cooling capacity.

  (3) Other DX units, including those that control space temperature by modulating the airflow to the space, shall comply with the requirements of Table E 503.5.3. [ASHRAE 90.1:6.5.1.3]

  been previously cooled, either by mechanical cooling or by economizer systems.

  (4) Other simultaneous operation of heating and cooling systems to the same zone.

  Exceptions:

  (1) Zones for which the volume of air that is reheated, recooled, or mixed is less than the larger of the following:

  (a) For systems without DDC, 30 percent of the zone design peak supply.

  (b) For systems with DDC, the minimum primary airflow rate required to meet the Simplified Procedure ventilation requirements of Chapter 4 or ASHRAE 62.1 for the zone, permitted to be the average airflow rate as allowed by Chapter 4 or ASHRAE 62.1.

  (c) Any higher rate that can be demonstrated, to the satisfaction of the Authority Having Jurisdiction, to reduce overall system annual energy use by offsetting reheat/recool energy losses through a reduction in outdoor air intake for the system.

  (d) The airflow rate required to be in accordance with applicable codes or accreditation standards, such as pressure relationships or minimum air change rates.

  (2) Zones with DDC that comply with the following:

  (a) The airflow rate in dead band between heating and cooling does not exceed the larger of the following:

  (i) The minimum primary airflow rate required to meet the Simplified Procedure ventilation requirements of Chapter 4 or ASHRAE 62.1 for the zone, permitted to be the average airflow rate as allowed by Chapter 4 or ASHRAE 62.1.

  (ii) A higher rate that can be demonstrated, to the satisfaction of the Authority Having Jurisdiction, to reduce overall system annual energy use by offsetting reheat/recool energy losses through a reduction in outdoor air intake.

  (iii) The airflow rate required with applicable codes or accreditation standards, such as pressure relationships or minimum air change rates.

  (b) The airflow rate that is reheated, recooled, or mixed shall be less than 50 percent of the zone design peak supply rate.

  (c) The first stage of heating consists of modulating the zone supply air temperature set

  TABLE E 503.5.3

  DX COOLING STAGE REQUIREMENTS FOR

  MODULATING AIRFLOW UNITS

  [ASHRAE 90.1: TABLE 6.5.1.3]

• CMC § 403.9 High relevance — show source text

  Table 403.9 Airstreams or Sources

  Description Air Class . . . . . . . . . . . 75

  403.10 Air Balance . . . . . . . . . . . . . . . . . . . 75

  404.0 Alternative Procedure for

  Multiple-Zone Systems Ventilation Efficiency . . . . . . . . . . . 76

  xxx

  404.1 System Ventilation Efficiency . . . . . 76

  404.2 Average Outdoor Air Fraction. . . . . 76

  404.3 Zone Ventilation Efficiency . . . . . . . 76

  405.0 Ventilation for Residential

  Occupancies. . . . . . . . . . . . . . . . . . 77

  405.1 General. . . . . . . . . . . . . . . . . . . . . . 77

  405.2 Ventilation Air Rate. . . . . . . . . . . . . 77

  405.3 Bathroom Exhaust . . . . . . . . . . . . . 77

  405.4 Kitchen Exhaust . . . . . . . . . . . . . . . 77

  405.5 Ventilation Openings . . . . . . . . . . . 77

  406.0 Evaporative Cooling System for Health Care Facilities . . . . . . . . 78

  407.0 Ventilation System Details . . . . . . . 78

  407.1 General. . . . . . . . . . . . . . . . . . . . . . 78

  407.2 Outdoor Air Intakes and

  Exhaust Outlets . . . . . . . . . . . . . . . 78

  407.3 Air Balance. . . . . . . . . . . . . . . . . . . 78

  407.4 Air Circulation . . . . . . . . . . . . . . . . . 78

  407.5 Variable Air Volume . . . . . . . . . . . . 79

  407.6 Economizers. . . . . . . . . . . . . . . . . . 79

  407.7 Unoccupied Turndown. . . . . . . . . . 79

  407.8 Building Pressurization . . . . . . . . . 80

  408.0 Filters . . . . . . . . . . . . . . . . . . . . . . . 80

  408.1 General. . . . . . . . . . . . . . . . . . . . . . 80

  408.2 Filters for Hospitals. . . . . . . . . . . . . 80

  408.3 Filters for Skilled Nursing Facilities, Intermediate Care Facilities, and Correctional

  Treatment Centers . . . . . . . . . . . . . 80

  408.4 Filters for Outpatient Facilities . . . . 80

  408.5 Filters for Recirculating

  Room Units. . . . . . . . . . . . . . . . . . . 80

• CMC § 62.1 Medium relevance — show source text

  Controls shall be designed to coordinate operation of the natural and mechanical ventilation systems. [ASHRAE 62.1:6.4.3] D. Naturally ventilated spaces shall also include a mechanical ventilation system designed in accordance with Section 120.1(c)3. Exception 1 to Section 120.1(c)2D: Spaces not served by a space-conditioning system. Exception 2 to Section 120.1(c)2D: Spaces where natural ventilation openings complying with Section 120.1(c)2 are either permanently open or have controls that prevent the openings from being closed during periods of expected occupancy. 3. Mechanical ventilation. Occupiable spaces shall be ventilated with a mechanical ventilation system capable of providing an outdoor airflow rate to the zone ( V z ) no less than Equation 120.1-F as described below:

  (Equation 120.1-F) V z = The larger of R p × P z or R a × A z

  Where:

  R p = 15 cubic feet per minute of outdoor airflow per person P z = The expected number of occupants. For spaces without fixed seating, the expected number of occupants shall be the expected number specified by the building designer or the default occupancy density in Table 120.1-A times the occupiable floor area of the zone, whichever is greater. For spaces with fixed seating, the expected number of occupants shall be determined in accordance with Section 1004.6 of the California Building Code. R a = The area-based minimum ventilation airflow rate in Table 120.1-A. A z = The net occupiable floor area of the ventilation zone in square feet.

  Exception 2 to Section 120.1(c)3: Transfer air. The rate of outdoor air required by Section 120.1(c)3 may be provided with air transferred from other ventilated space if: A. Use of transfer air is in accordance with Section 120.1(g); and B. The outdoor air that is supplied to all spaces combined, is sufficient to meet the requirements of Section 120.1(c)3 for each space individually. 4. Exhaust ventilation. The design exhaust airflow shall be determined in accordance with the requirements in Table 120.1-B. Exhaust makeup air shall be permitted to be any combination of outdoor air, recirculated air, or transfer air.

  [ASHRAE 62.1:6.5.1]

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  NONRESIDENTIAL, HOTEL/MOTEL OCCUPANCIES, AND COVERED PROCESSES—MANDATORY REQUIREMENTS

  TABLE 120.1-A—MINIMUM VENTILATION RATES	Col2	Col3	Col4	Col5
  OCCUPANCY CATEGORY	MINIMUM OCCUPANT LOAD DENSITY (persons/1,000 ft2)	AREA-BASED MINIMUM VENTILATION_ Ra_ (cfm/ft2)	AIR CLASS	NOTES
  Educational Facilities	Educational Facilities	Educational Facilities	Educational Facilities	Educational Facilities
  Daycare (through age 4)	14	0.

• CMC § 402.2.1.6 Medium relevance — show source text

  402.2.1.6(A)(1) Single Openings . . . . . . . . . . . . . . . 71

  Table Minimum Openable Areas:

  402.2.1.6(A)(2) Two Vertically

  Spaced Openings . . . . . . . . . . . . . . 71

  402.3 Mechanical Ventilation . . . . . . . . . . 71

  402.4 Outdoor Air Intakes. . . . . . . . . . . . . 71

  Table 402.4.1 Air Intake Minimum

  Separation Distance . . . . . . . . . . . . 72

  403.0 Ventilation Rates . . . . . . . . . . . . . . 72

  403.1 General. . . . . . . . . . . . . . . . . . . . . . 72

  403.2 Zone Calculations. . . . . . . . . . . . . . 73

  403.3 Single-Zone Systems . . . . . . . . . . . 73

  403.4 One Hundred Percent Outdoor

  Air Systems . . . . . . . . . . . . . . . . . . 73

  403.5 Multiple-Zone Recirculating Systems . . . . . . . . . . . . . . . . . . . . . 73

  403.6 Design for Varying Operating Conditions. . . . . . . . . . . . . . . . . . . . 74

  403.7 Exhaust Ventilation. . . . . . . . . . . . . 74

  403.8 Dynamic Reset . . . . . . . . . . . . . . . . 75

  403.9 Air Classification and

  Recirculation. . . . . . . . . . . . . . . . . . 75

  Table 403.9 Airstreams or Sources

  Description Air Class . . . . . . . . . . . 75

  403.10 Air Balance . . . . . . . . . . . . . . . . . . . 75

  404.0 Alternative Procedure for

  Multiple-Zone Systems Ventilation Efficiency . . . . . . . . . . . 76

  xxx

  404.1 System Ventilation Efficiency . . . . . 76

  404.2 Average Outdoor Air Fraction. . . . . 76

  404.3 Zone Ventilation Efficiency . . . . . . . 76

  405.0 Ventilation for Residential

  Occupancies. . . . . . . . . . . . . . . . . . 77

  405.1 General. . . . . . . . . . . . . . . . . . . . . . 77

  405.2 Ventilation Air Rate. . . . . . . . . . . . . 77

  405.3 Bathroom Exhaust . . . . . . . . . . . . . 77

  405.4 Kitchen Exhaust . . . . . . . . . . . . . . . 77

  405.5 Ventilation Openings . . . . . . . . . . . 77

  406.0 Evaporative Cooling System for Health Care Facilities . . . . . . . . 78

  407.0 Ventilation System Details . . . . . . . 78

  407.1 General. . . . . . . . . . . . . . . . . . . . . . 78

  407.2 Outdoor Air Intakes and

• CMC § 160.2 Medium relevance — show source text

  Exception to Section 160.2(b)2 The following sections of ASHRAE 62.2 shall not be required for compliance: Section 4.1.1, Section 4.1.2, Section 4.1.4, Section 4.2, Section 4.3, Section 4.6, Section 5, Section 6.1.1, Section 6.1.3 and Normative Appendix A. A. Amendments to ASHRAE 62.2 requirements. i. Window operation . Window operation is not a permissible method of providing the dwelling unit ventilation airflow specified in Subsection iv or v below. ii. Central fan integrated (CFI) ventilation systems . a. Continuous operation prohibition. Continuous operation of a dwelling unit's central forced air system air handlers used in CFI ventilation systems is not a permissible method of providing the whole-dwelling unit ventilation airflow required by Section 160.2(b)2Aiv. Exception to Section 160.2(b)2Aiia: The Energy Commission may approve continuous operation of central fan integrated ventilation systems pursuant to Section 10-109(h). b. Outdoor air damper(s). A motorized damper(s) shall be installed on the connected ventilation duct(s) of CFI systems that prevents all airflow into or out of the space-conditioning duct system when the damper(s) is closed. c. Damper control. The required motorized damper(s) shall be controlled to be in an opened position when outdoor air ventilation is required for compliance, and shall be in the closed position when ventilation air is not required. The damper(s) shall be closed whenever the space-conditioning system air handling unit is not operating. If the outdoor airflow for the CFI ventilation system is fan-powered, then the outdoor air fan shall not operate when the required motorized damper(s) on the outdoor air ventilation duct(s) is closed.

  d. Variable ventilation. CFI ventilation systems shall incorporate controls that track outdoor air ventilation run time, and either open or close the required motorized damper(s) depending on whether or not outdoor air ventilation is required for compliance with Section 160.2(b)2Aiv. During periods when comfort conditioning is not called for by the space-conditioning thermostat, the CFI ventilation system controls shall operate the space-conditioning system central fan and outdoor air damper(s) when necessary to ensure compliance with the minimum outdoor air ventilation required by Section 160.2(b)2Aiv in accordance with applicable variable mechanical ventilation methods specified in ASHRAE 62.2 Section 4.5.

  iii. Air filtration. Air filtration shall conform to the specifications in Section 160.2(b)1. Compliance with ASHRAE 62.2 Sections 6.7 (Minimum Filtration) and 6.7.1 (Filter Pressure Drop) shall not be required. iv. Whole-dwelling unit mechanical ventilation . Multifamily attached dwelling units shall comply with Subsections a and b below.

  a. Mechanical ventilation airflow shall be provided at rates greater than or equal to the value determined in accordance with Equation 160.2-B. Total Required Ventilation Rate [ASHRAE 62.2:4.1.1]: (Equation 160.2-B) Q tot = 0.03 A floor + 7.5( N br + 1)

  where:

  Q tot = total required ventilation rate, cfm.

• CMC § 2.3.2 Medium relevance — show source text

  If the verification procedure in Section RA3.2.3.2 is used for compliance, the system’s thermostat shall conform to the specifications in Section 110.12. Ducted systems shall comply with the minimum system airflow rate requirement in Section 170.2(c)3BiaII.

  b. For air-cooled air conditioners and air-source heat pumps, including but not limited to ducted split systems, ducted packaged systems, small duct high velocity systems and mini-split systems, which are of a type that cannot comply with the requirements of Section 170.2(c)3Bi: I. The installer shall confirm the refrigerant charge using the weigh-in charging procedure specified in Reference Residential Appendix Section RA3.2.3.1, as verified by a ECC-Rater according to the procedures specified in Reference Residential Appendix Section RA3.2.3.2; and II. Systems that utilize forced air ducts shall comply with the minimum system airflow rate requirement in Section 170.2(c)3BiaII, provided the system is of a type that can be verified using the procedures in RA3.3 or an approved alternative procedure in RA1. Exception 1 to Section 170.2(c)3Bi: Packaged systems for which the manufacturer has verified correct system refrigerant charge prior to shipment from the factory are not required to have refrigerant charge confirmed through field verification and diagnostic testing. The installer of these packaged systems shall certify that the packaged system was precharged at the factory and has not been altered in a way that would affect the charge. Ducted systems shall comply with minimum system airflow rate requirement in Section 170.2(c)3Bib, provided that the system is of a type that can be verified using the procedure specified in RA3.3 or an approved alternative in RA1. Exception 2 to Section 170.2(c)3Bi: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four habitable stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. ii. Space-conditioning distribution systems. All space-conditioning systems shall meet all applicable requirements of a or b below:

  a. High performance attics. Air handlers or ducts are allowed to be in ventilated attic spaces when the roof and ceiling insulation level meet Option B in Table 170.2-A. b. Duct and air handlers located in conditioned space. Duct systems and air handlers of HVAC systems shall be located in conditioned space, and confirmed by field verification and diagnostic testing to meet the criterion of Reference Residential Appendix RA3.1.4.3.8. NOTE: Gas heating appliances installed in conditioned spaces must meet the combustion air requirements of California Mechanical Code Chapter 7, as applicable. iii. Central fan integrated ventilation systems—systems serving individual dwelling units. Central forced air system fans used to provide outside air shall have an air-handling unit fan efficacy less than or equal to the maximum W/cfm specified in a or b below. The airflow rate and fan efficacy requirements in this section shall be confirmed through field verification and diagnostic testing in accordance with all applicable procedures specified in Reference Residential Appendix RA3.3. Central Fan Integrated Ventilation Systems shall be certified to the Energy Commission as Intermittent Ventilation Systems as specified in Reference Residential Appendix RA3.7.4.2.

• CMC § 5.08 High relevance — show source text

  minute per square foot = 5.08 [(L/s)/m [2] ]

  405.0 Ventilation for Residential Occupancies.

  405.1 General. Rooms or occupied spaces within residential occupancies, where the occupants are nontransient, shall be designed to have mechanical ventilation and exhaust air in accordance with Section 405.2 through Section 405.5.

  405.1.1 Natural Ventilation. Where approved by the Authority Having Jurisdiction, natural ventilation shall be permitted for Climate Zone 1, Climate Zone 2, or for thermally conditioned buildings for less than 876 hours

  per year.

  405.2 Ventilation Air Rate. The required mechanical ventilation outdoor air rate ( Qtot ) shall be as calculated in accordance with Equation 405.2.

  Exception: For existing buildings and where permitted by the Authority Having Jurisdiction, the total mechanical ventilation ( Qtot ) is not required where Qtot is calculated to be less than 15 ft [3] /min (7.08 L/s).

  Qtot = 0.03 Afloor + 7.5 ( Nbr + 1) (Equation 405.2)

  Where:

  Qtot = Total required ventilation outdoor air rate, CFM (L/s) Afloor = Floor area, ft [2] (m [2] ) Nbr = Number of bedrooms more than 1

  For SI Units: 1 square foot = 0.0929 m [2], 1 cubic foot per minute = 0.0283 m [3] /min, 1 cubic foot per minute = 0.4719 L/s

  405.2.1 Reduced Ventilation Air Rate. Where permitted by the Authority Having Jurisdiction, the mechanical ventilation air rate required in Section 405.2 shall be permitted to be reduced where an infiltration rate is determined in accordance with ASTM E779.

  405.3 Bathroom Exhaust. A mechanical exhaust directly to the outdoors shall be provided in each room containing a bathtub, shower, or tub/shower combination. The fan shall run intermittently (on demand) or continuously. A readily accessible manual control designed to be operated as needed or an automatic control shall be provided for intermittent operations. [HCD 1 & HCD 2] Each bathroom shall also be mechanically ventilated in accordance with Division 4.5 of the California Green Building Standards Code (CALGreen).

  405.3.1 Exhaust Rate. The exhaust rate shall be not less than 50 ft [3] /min (23.6 L/s) for intermittent operation and 25 ft [3] /min (11.8 L/s) for continuous operation. 405.4 Kitchen Exhaust. A mechanical exhaust system that discharges directly to the outdoors shall be provided in each kitchen. The fan shall run intermittently (on demand) or continuously. A readily accessible manual control designed to be operated as needed or an automatic control shall be provided for intermittent operations.

  Exception: Recirculating systems installed in accordance with Section 516.0 and the manufacturer’s installation

  instructions.

• CMC § 403.2.1. High relevance — show source text

  Pz = Zone population: see Section 403.2.1. Ra = Area outdoor air rate, CFM/ft [2] . See Section 403.2.1.

  Rp = People outdoor air rate, CFM/person. See Section 403.2.1.

  Vbz = Breathing zone outdoor airflow, CFM. See Section 403.2.1.

  Vdz = Zone discharge airflow, CFM. The expected discharge (supply) airflow to the zone that includes primary airflow and secondary recirculated airflow, CFM.

  Vot = Outdoor air intake flow, CFM. See Section 403.3, Section 403.4, and Section 403.5.2.

  Vou = Uncorrected outdoor air intake, CFM. See Section 403.5.1.

  Voz = Zone outdoor airflow, CFM. See Section 403.2.3. Vps = System primary airflow, CFM. The total primary airflow supplied to all zones served by the system from the air-handling unit at which the outdoor air intake is located.

  Vpz = Zone primary airflow, CFM. The zone primary airflow to the ventilation zone, including outdoor air and recirculated air.

  Xs = Average outdoor air fraction: At the primary air handler, the fraction of outdoor air intake flow in the system primary airflow. Zpz = Primary outdoor air fraction: The outdoor air fraction required in the primary air supplied to the ventilation zone prior to the introduction of any secondary recirculation air. [ASHRAE 62.1:A3]

  For SI Units: 1 square foot = 0.0929 m [2], 1 cubic foot per minute =

  0.0283 m [3] /min, 1 cubic foot per minute = 0.4719 L/s, 1 cubic foot per

  minute per square foot = 5.08 [(L/s)/m [2] ]

  405.0 Ventilation for Residential Occupancies.

  405.1 General. Rooms or occupied spaces within residential occupancies, where the occupants are nontransient, shall be designed to have mechanical ventilation and exhaust air in accordance with Section 405.2 through Section 405.5.

  405.1.1 Natural Ventilation. Where approved by the Authority Having Jurisdiction, natural ventilation shall be permitted for Climate Zone 1, Climate Zone 2, or for thermally conditioned buildings for less than 876 hours

  per year.

  405.2 Ventilation Air Rate. The required mechanical ventilation outdoor air rate ( Qtot ) shall be as calculated in accordance with Equation 405.2.

  Exception: For existing buildings and where permitted by the Authority Having Jurisdiction, the total mechanical ventilation ( Qtot ) is not required where Qtot is calculated to be less than 15 ft [3] /min (7.08 L/s).

  Qtot = 0.03 Afloor + 7.5 ( Nbr + 1) (Equation 405.2)

  Where:

  Qtot = Total required ventilation outdoor air rate, CFM (L/s) Afloor = Floor area, ft [2] (m [2] ) Nbr = Number of bedrooms more than 1

  For SI Units: 1 square foot = 0.0929 m [2], 1 cubic foot per minute = 0.0283 m [3] /min, 1 cubic foot per minute = 0.4719 L/s

• CMC § 403.7 Medium relevance — show source text

  1
  Table 403.7_Notes 11 & 12_
  
  
  ||||X|X||||||||||||||||||||

  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.

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  CHAPTER 4

  VENTILATION AIR

  401.0 General.

  401.1 Applicability. This chapter contains requirements for ventilation air supply, exhaust, and makeup air requirements for occupiable spaces within a building. [OSHPD 1, 1R, 2, 3, 4 & 5] See Sections 406.0 through 419.0. [SFM] Air filters shall comply with all requirements of Part 12, Title 24, Chap- ter 12-71, SFM Standard 12-71-1. Spaces within buildings, except those within a dwelling unit in residential occupancies where occupants are nontransient, shall comply with Section 402.0 through Section 404.0. Requirements for ventilation air rate for dwelling units in residential occupancies, where the occupants are nontransient, shall be in accordance with Section 405.0 or ASHRAE 62.2.

  401.2 Indoor Swimming Pools. The design of ventilation systems serving an indoor aquatic facility (natatorium) shall comply with the Uniform Swimming Pool, Spa and Hot Tub Code (USPSHTC).

  401.3 Filters. [BSC-CG & DSA-SS] In mechanically ven- tilated buildings, provide regularly occupied areas of the building with air filtration media for outside and return air that provides at least a Minimum Efficiency Reporting Value (MERV) of 13. MERV 13 filters shall be installed prior to occupancy, and recommendations for maintenance with fil- ters of the same value shall be included in the operation and maintenance manual in compliance with Chapter 5, Division 5.5 of the California Green Building Standards Code (CAL- Green).

  Exception: Existing mechanical equipment.

  401.3.1 Labeling. Installed filters shall be clearly labeled by the manufacturer indicating the MERV rating.

  402.0 Ventilation Air.

  402.1 Occupiable Spaces. Occupiable spaces listed in Table 402.1 shall be designed to have ventilation (outdoor) air for occupants in accordance with this chapter. [DSA-SS] Ven- tilation air requirements for occupancies regulated by the California Energy Commission are found in the California Energy Code.

  [CEC] Ventilation air requirements for occupancies regu- lated by the California Energy Commission and found in the California Energy Code supersede those of the California Mechanical Code.

• CMC § 416.2 Medium relevance — show source text

  0_
  414.0
  415.0
  416.0 – 416.2
  416.3
  416.4
  417.0
  418.0
  419.0
  Table 4-A
  Table 4-B
  Table 4-C
  Table 402.1
  Table 403.7_Notes 11 & 12_
  
  
  |X|||||||X||||||||||||||||| |Adopting Agency
  Adopt Entire Chapter
  Adopt Entire Chapter as
  amended (amended sections
  listed below)
  Adopt only those sections
  that are listed below
  Chapter/Section
  401.1
  401.3
  401.3.1
  402.1
  402.1.2
  402.2
  402.3
  403.0
  403.7.2.1 – 403.7.2.4
  405.3
  406.0
  407.0
  408.0
  409.0
  410.0
  411.0
  412.0
  413.0
  414.0
  415.0
  416.0 – 416.2
  416.3
  416.4
  417.0
  418.0
  419.0
  Table 4-A
  Table 4-B
  Table 4-C
  Table 402.1
  Table 403.7_Notes 11 & 12_
  
  
  ||||X|X||||||||||||||||||||

  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.

  2025 CALIFORNIA MECHANICAL CODE 67

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  ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

  CHAPTER 4

  VENTILATION AIR

  401.0 General.

  401.1 Applicability. This chapter contains requirements for ventilation air supply, exhaust, and makeup air requirements for occupiable spaces within a building. [OSHPD 1, 1R, 2, 3, 4 & 5] See Sections 406.0 through 419.0. [SFM] Air filters shall comply with all requirements of Part 12, Title 24, Chap- ter 12-71, SFM Standard 12-71-1. Spaces within buildings, except those within a dwelling unit in residential occupancies where occupants are nontransient, shall comply with Section 402.0 through Section 404.0. Requirements for ventilation air rate for dwelling units in residential occupancies, where the occupants are nontransient, shall be in accordance with Section 405.0 or ASHRAE 62.2.

• CMC § 0.0929 Medium relevance — show source text

  For SI Units: 1 square foot = 0.0929 m [2], 1 cubic foot per minute = 0.0283 m [3] /min, 1 cubic foot per minute = 0.4719 L/s

  405.2.1 Reduced Ventilation Air Rate. Where permitted by the Authority Having Jurisdiction, the mechanical ventilation air rate required in Section 405.2 shall be permitted to be reduced where an infiltration rate is determined in accordance with ASTM E779.

  405.3 Bathroom Exhaust. A mechanical exhaust directly to the outdoors shall be provided in each room containing a bathtub, shower, or tub/shower combination. The fan shall run intermittently (on demand) or continuously. A readily accessible manual control designed to be operated as needed or an automatic control shall be provided for intermittent operations. [HCD 1 & HCD 2] Each bathroom shall also be mechanically ventilated in accordance with Division 4.5 of the California Green Building Standards Code (CALGreen).

  405.3.1 Exhaust Rate. The exhaust rate shall be not less than 50 ft [3] /min (23.6 L/s) for intermittent operation and 25 ft [3] /min (11.8 L/s) for continuous operation. 405.4 Kitchen Exhaust. A mechanical exhaust system that discharges directly to the outdoors shall be provided in each kitchen. The fan shall run intermittently (on demand) or continuously. A readily accessible manual control designed to be operated as needed or an automatic control shall be provided for intermittent operations.

  Exception: Recirculating systems installed in accordance with Section 516.0 and the manufacturer’s installation

  instructions.

  405.4.1 Exhaust Rate. For intermittent-controlled operations, the exhaust rate shall be not less than 100 ft [3] /min (47.2 L/s) for range hoods or 300 ft [3] /min (142 L/s) for mechanical exhaust fans including downdraft appliances. For continuous operated ventilation, the exhaust rate shall be not less than 50 ft [3] /min (23.6 L/s). 405.5 Ventilation Openings. Occupiable spaces shall be provided with a readily accessible ventilation opening openable to the outdoors. The opening shall be not less than 5 square feet (0.464 m [2] ) or 4 percent of the occupied floor area. The openable area shall be based on free, unobstructed area through the opening.

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  VENTILATION AIR

  406.0 Evaporative Cooling System for Health Care Facilities. [OSHPD 1, 2, 3, 4 & 5] Direct evaporative cool- ing systems where the air directly contacts the wetted surface or spray shall be limited in health facilities to nonpatient areas such as laundry rooms, and boiler or machinery rooms. Similar rooms with high heating-producing equipment will be consid- ered when specifically approved by the enforcing agency. The evaporative pads shall be a synthetic type. Filters shall be required in accordance with Tables 4-B and 4-C except utility rooms, i.e.: boiler or machinery rooms.

• CMC § 2.5 Medium relevance — show source text

  iv. Attic ventilation shall comply with the California Residential Code, Title 24, Part 2.5, Section R806. Exception 1 to Section 150.2(b)1J: Dwelling units with at least R-38 existing insulation installed at the ceiling level. Exception 2 to Section 150.2(b)1J: Dwelling units where the alteration would directly cause the disturbance of asbestos.

  Exception 3 to Section 150.2(b)1J: Dwelling units with knob and tube wiring located in the vented attic.

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  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

  SINGLE-FAMILY RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS TO EXISTING RESIDENTIAL BUILDINGS

  Exception 4 to Section 150.2(b)1J: Where the accessible space in the attic is not large enough to accommodate the required R -value, the entire accessible space shall be filled with insulation provided such installation does not violate Section 806.3 of Title 24, Part 2.5. Exception 5 to Section 150.2(b)1J: Where the attic space above the altered dwelling unit is shared with other dwelling units and the requirements of Section 150.2(b)1J are not triggered for the other dwelling units. K. Lighting. The altered lighting system shall meet the lighting requirements of Section 150.0(k). The altered luminaires shall meet the luminaire efficacy requirements of Section 150.0(k). Where existing screw-base sockets are present in ceiling-recessed luminaires, removal of these sockets is not required provided that new JA8-compliant trim kits or lamps designed for use with recessed downlights or luminaires are installed. L. Mechanical ventilation for indoor air quality—entirely new or complete replacement ventilation systems. Entirely new or complete replacement ventilation systems shall comply with all applicable requirements in Section 150.0(o). An entirely new or complete replacement ventilation system includes a new ventilation fan component and an entirely new duct system. An entirely new or complete replacement duct system is constructed of at least 75 percent new duct material, and up to 25 percent may consist of reused parts from the dwelling unit's existing duct system, including but not limited to registers, grilles, boots, air filtration devices and duct material, if the reused parts are accessible and can be sealed to prevent leakage. M. Mechanical ventilation for indoor air quality—altered ventilation systems. Altered ventilation system components or newly installed ventilation equipment serving the alteration shall comply with Section 150.0(o) as applicable subject to the requirements specified in Subsections i and ii below. i. Whole-dwelling unit mechanical ventilation. a. Whole-dwelling unit airflow. If the whole-dwelling ventilation fan is altered or replaced, then one of the following Subsections 1 or 2 shall be used for compliance as applicable.

  1. Dwellings that were required by a previous building permit to comply with the whole-dwelling unit airflow requirements in Section 150.0(o) shall meet or exceed the whole-dwelling unit mechanical ventilation airflow specified in Section 150.0(o)1C, 150.0(o)1E or 150.0(o)1F as confirmed through field verification and diagnostic testing in accordance with the applicable procedures specified in Reference Residential Appendix RA3.7.
• CMC § 120.10 Medium relevance — show source text

  4(f)2 Variable Air volume (VAV) 120.10(a), 140.4(c)2, 140.4(d), 140.9(c)4, 141.0(a)2, 141.0(b)3, 160.2(c)7, 170.2(c)4A, 170.2(c)4B, Table 170.2-B, Table 170.2-C, Table 180.2-D Capacity heat pump (VCHP) 150.1(b)3, 170.1(d)2 Exhaust 140.9(c)3 Flow control 140.4(k)6, 160.3(d), 170.2(c)4I Fluid flow 140.4(k)1, 170.2(c)4I Speed 120.6(a), 120.6(b)5 Speed compressor 120.6(a)3, 120.6(a)7, 150.0(m)13, 160.3(b)5L Speed control 140.4(k)6, 140.9(b) Speed drive 120.6(e), 120.9(b), 140.4(c)1, 140.4(k)6, 160.4(e), 170.2(c)4I Speed fan 120.6(a)4, 120.6(a)8, 120.6(b)1, 150.0(o), 160.2(b)2 Ventilation 150.0(o), 160.2(b)2A Vending Machine 140.6(a)3J, K, L Vent Damper 110.2(d), 110.2(f) Vented Attic 150.0(a), 150.0(g), 150.2(b)1J, 160.1(a), 160.1(d), 180.2(b)1 Vented Range Hood 150.0(o), Table 150.0-E, 150.0(v), 160.2(b)2B, Table 160.2-E Ventilated Attic 150.1(c)9, 170.2(c), 180.2(a)1 Ventilation 120.1, 140.4(b)4, 150.0(o), 160.3(d)2 Air 120.1(d), 120.2(e), 130.1(f), 140.4(e), 140.4(m), 140.9(b), 150.0(o), 150.1(b), 150.2(a)2C, 160.2(b)2B, 160.2(c), 160.5(b), 170.1(d), 170.2(c), 180.1(a), 180.3(a) And indoor air quality 120.1, 150.0(o), 160.2(b)2 Cooling 150.1(b)3, 150.1(c)12, 150.2(a), 170.1(d) Dampers 150.0(m)8, 160.3(b) Device 10-103(b), 120.1(d), 160.2(c)5 Doors 120.6(f) Fan 120.6(f), 150.2(b)1L, 180.2(b) Load 140.4(b)4, 170.2(c) Only 120.1(h)

• CMC § 403.0 Medium relevance — show source text

  403.0 Ventilation Rates. [Not permitted for OSHPD 1, 2, 3, 4 & 5 spaces listed in Table 4-A]

  403.1 General. The design outdoor air intake flow rate for a ventilation system shall be determined in accordance with Section 403.2 through Section 403.10.

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  VENTILATION AIR

  403.2 Zone Calculations. Ventilation zone parameters shall be determined in accordance with Section 403.2.1 through Section 403.2.3 for ventilation zones served by the ventilation system, except that the ventilation rates from ASHRAE/ASHE 170 shall be used for the occupancy categories, as applicable. [ASHRAE 62.1:6.2.1]

  403.2.1 Breathing Zone Outdoor Airflow. The outdoor airflow required in the breathing zone ( Vbz ) of the occupiable space or spaces in a ventilation zone shall be not less than the value determined in accordance with Equation 403.2.1.

  Vbz = Rp•Pz + Ra• Az (Equation 403.2.1)

  Where: Az = zone floor area, the net occupiable floor area of the ventilation zone, ft [2] (m [2] ). Pz = zone population, the number of people in the ventilation zone during usage. Rp= outdoor airflow rate required per person (CFM/person) as determined from Table 402.1. Ra= outdoor airflow rate required per unit area (CFM/ft [2] ) as determined from Table 402.1.

  [ASHRAE 62.1:6.2.1.1] For SI Units: 1 square foot = 0.0929 m [2], 1 cubic foot per minute = 0.0283 m [3] /min, 1 cubic foot per minute = 0.4719 L/s, 1 cubic foot per minute per square foot = 5.08 [(L/s)/m [2] ] 403.2.2 Zone Air Distribution Effectiveness. The zone air distribution effectiveness ( Ez ) shall be determined in accordance with Table 403.2.2. [ASHRAE 62.1:6.2.1.2] 403.2.2.1 Stratified Air Distribution Systems. A stratified air distribution system shall be designed in accordance with Section 403.2.2.1.1 through Section 403.2.2.2.2, or the zone air distribution effectiveness ( Ez ) shall be determined in accordance with ASHRAE 62.1. [ASHRAE 62.1:6.2.1.2.1] 403.2.2.1.1 Supply Air. Cool air shall be at least 4°F (2°C) less than the average room air temperature. [ASHRAE 62.1:6.2.1.2.1.1] 403.2.2.1.2 Return Air. The return air openings or pathways shall be located not less than 9 feet (2743 mm) above the floor. [ASHRAE 62.1:6.2.1.2.1.2]