Air classification, recirculation limits and transfer air rules

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

• CMC § 403.9.2 High relevance — show source text

  403.9.2 Class 2 Air. Recirculation of Class 2 air within the space of origin shall be permitted. Recirculation or transfer of Class 2 air to other Class 2 or Class 3 spaces shall be permitted, provided that the other spaces are used for the same or similar purpose or task and involve the same or similar pollutant sources as the Class 2 space. Transfer of Class 2 air to toilet rooms shall be permitted. Recirculation or transfer of Class 2 air to Class 4 spaces shall be permitted. Class 2 air shall not be recirculated or transferred to Class 1 spaces.

  Exception: When using any energy recovery device, recirculation from leakage, carryover, or transfer from the exhaust side of the energy recovery device shall be permitted but shall not be counted as outdoor air. Exhaust air transfer ratio of Class 2 air shall not exceed 10 percent of the outdoor air intake flow. {ASHRAE 62.1:5.18.3.2 – 5.18.3.2.5}

  403.9.3 Class 3 Air. Recirculation of Class 3 air within the space of origin shall be permitted. Class 3 air shall not be recirculated or transferred to any other space.

  Exception: When using any energy recovery device, recirculation from leakage, carryover, or transfer from the exhaust side of the energy recovery device shall be permitted but shall not be counted as outdoor air. Exhaust air transfer ratio of Class 3 air shall not exceed 5 percent of the outdoor air intake flow. {ASHRAE 62.1:5.18.3.3 – 5.18.3.3.2}

  403.9.4 Class 4 Air. Class 4 air shall not be recirculated or transferred to any space or recirculated within the space of origin. [ASHRAE 62.1:5.18.3.4]

  403.10 Air Balance. All mechanical ventilation systems shall be tested, balanced, and operated to demonstrate that the installation and performance of the systems are in accordance with the design intent. All testing and balancing shall be performed by a technician certified by the Associated Air Balance Council (AABC), the National Environmental Balancing Bureau (NEBB), the Testing, Adjusting and Balancing Bureau (TABB), or other equivalent approved agencies.

  Exception: For single family residential, compliance with Section 403.10 shall not be required.

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  VENTILATION AIR

  404.0 Alternative Procedure for Multiple-Zone Sys- tems Ventilation Efficiency.

  404.1 System Ventilation Efficiency. The system ventilation efficiency shall equal the lowest zone ventilation efficiency among the ventilation zones served by the air handler in accordance with Equation 404.1. [ASHRAE 62.1:A1.3] This section presents an alternative procedure for calculating the system ventilation efficiency ( Ev ) for multiple zone recirculating systems that shall be used when Section 403.5.1.3 is not used.

  Ev = minimum ( Evz ) (Equation 404.1)

  404.2 Average Outdoor Air Fraction. The average outdoor air fraction ( X s) for the ventilation system shall be determined in accordance with Equation 404.2.

• CMC § 402.1 High relevance — show source text

  Air (return, transfer, or exhaust air) leaving each space or location shall be designated at an expected air-quality classification not less than that shown in Table 402.1, Table 403.7, or Table 403.9 or as approved by the Authority Having Jurisdiction. Air leaving spaces or locations that are not listed in Table 402.1, Table 403.7, or Table 403.9 shall be designated with the same classification as air from the most similar space or location listed in terms of occupant activities and building construction.

  Exception: Air from spaces where environmental tobacco smoke (ETS) is present. (Classification of air from spaces where ETS is present is not addressed. Spaces that are expected to include ETS do not have a classification listed in Table 402.1.)

  [ASHRAE 62.1:5.18.1]

  TABLE 403.9

  AIRSTREAMS OR SOURCES DESCRIPTION AIR CLASS

  [ASHRAE 62.1: TABLE 6-3]

  DESCRIPTION	AIR CLASS
  Kitchen grease hoods	4
  Kitchen hoods other than grease	3
  Diazo printing equipment discharge	4
  Hydraulic elevator machine room	2
  Laboratory hoods	4
  Paint spray booths	4
  Refrigerating machinery rooms	3

  403.9.1 Class 1 Air. Recirculation or transfer of Class 1 air to any space shall be permitted. [ASHRAE 62.1:5.18.3.1]

  403.9.2 Class 2 Air. Recirculation of Class 2 air within the space of origin shall be permitted. Recirculation or transfer of Class 2 air to other Class 2 or Class 3 spaces shall be permitted, provided that the other spaces are used for the same or similar purpose or task and involve the same or similar pollutant sources as the Class 2 space. Transfer of Class 2 air to toilet rooms shall be permitted. Recirculation or transfer of Class 2 air to Class 4 spaces shall be permitted. Class 2 air shall not be recirculated or transferred to Class 1 spaces.

  Exception: When using any energy recovery device, recirculation from leakage, carryover, or transfer from the exhaust side of the energy recovery device shall be permitted but shall not be counted as outdoor air. Exhaust air transfer ratio of Class 2 air shall not exceed 10 percent of the outdoor air intake flow. {ASHRAE 62.1:5.18.3.2 – 5.18.3.2.5}

  403.9.3 Class 3 Air. Recirculation of Class 3 air within the space of origin shall be permitted. Class 3 air shall not be recirculated or transferred to any other space.

  Exception: When using any energy recovery device, recirculation from leakage, carryover, or transfer from the exhaust side of the energy recovery device shall be permitted but shall not be counted as outdoor air. Exhaust air transfer ratio of Class 3 air shall not exceed 5 percent of the outdoor air intake flow. {ASHRAE 62.1:5.18.3.3 – 5.18.3.3.2}

• CMC § 403.7.2.3 High relevance — show source text

  403.7.2.3 Exhaust Inlet Distribution. [HCD 1 & 2] To ensure proper exhaust of contaminated air and fumes from parking garages, exhaust systems utilizing multiple exhaust inlets shall be designed so that exhaust inlets are distributed in such a manner

  that no portion of the parking garage is more than 50 feet (15 240 mm) from an exhaust inlet. Such exhaust inlets shall be installed so that the highest elevation of the exhaust inlet is no greater than 12 inches (305 mm) below the lowest ceiling level.

  Exception: Garage exhaust systems designed with- out distributed exhaust inlets may have their exhaust inlets designed based on the principles of engineering and mechanics and shall provide the minimum required exhaust rate in Table 403.7.

  403.7.2.4 Exhaust System Operation. [HCD 1 & 2] Exhaust systems shall operate continuously unless one of the exceptions to continuous operation of Section 403.7.2 is utilized.

  403.8 Dynamic Reset. The system shall be permitted to be designed to reset the outdoor air intake flow ( Vot ), the space or ventilation zone airflow ( Voz ) as operating conditions change, or both. [ASHRAE 62.1:6.2.6]

  403.9 Air Classification and Recirculation. Air shall be

  classified as shown in Table 402.1, Table 403.7, or Table 403.9, and its recirculation shall be limited in accordance with Section

  403.9.1 through Section 403.9.4. {ASHRAE 62.1:5.18} Recirculated air shall not be taken from prohibited locations in accordance with Section 311.3.

  Air (return, transfer, or exhaust air) leaving each space or location shall be designated at an expected air-quality classification not less than that shown in Table 402.1, Table 403.7, or Table 403.9 or as approved by the Authority Having Jurisdiction. Air leaving spaces or locations that are not listed in Table 402.1, Table 403.7, or Table 403.9 shall be designated with the same classification as air from the most similar space or location listed in terms of occupant activities and building construction.

  Exception: Air from spaces where environmental tobacco smoke (ETS) is present. (Classification of air from spaces where ETS is present is not addressed. Spaces that are expected to include ETS do not have a classification listed in Table 402.1.)

  [ASHRAE 62.1:5.18.1]

  TABLE 403.9

  AIRSTREAMS OR SOURCES DESCRIPTION AIR CLASS

  [ASHRAE 62.1: TABLE 6-3]

  DESCRIPTION	AIR CLASS
  Kitchen grease hoods	4
  Kitchen hoods other than grease	3
  Diazo printing equipment discharge	4
  Hydraulic elevator machine room	2
  Laboratory hoods	4
  Paint spray booths	4
  Refrigerating machinery rooms	3

  403.9.1 Class 1 Air. Recirculation or transfer of Class 1 air to any space shall be permitted. [ASHRAE 62.1:5.18.3.1]

• CMC § 160.2 High relevance — show source text

  7. Design and control requirements for quantities of outdoor air . A. All mechanical ventilation and space-conditioning systems shall be designed with and have installed ductwork, dampers and controls to allow outside air rates to be operated at the minimum levels specified in Section 160.2(c)3 or the rate required for make-up of exhaust systems that are required for an exempt or covered process, for control of odors or for the removal of contaminants within the space. B. All variable air volume mechanical ventilation and space-conditioning systems shall include dynamic controls that maintain measured outside air ventilation rates within 10 percent of the required outside air ventilation rate at both full and reduced supply airflow conditions. Fixed minimum damper position is not considered to be dynamic and is not an allowed control strategy. C. Measured outdoor air rates of constant volume mechanical ventilation and space-conditioning systems shall be within 10 percent of the required outside air rate.

  8. Air classification and recirculation limitations. Air classification and recirculation limitations of air shall be based on the air classification as listed in Table 160.2-B or Table 160.2-D, in accordance with the following: A. Class 1 air is air with low contaminant concentration, low sensory-irritation intensity or inoffensive odor. Recirculation or transfer of Class 1 air to any space shall be permitted; [ASHRAE 62.1:5.13.3.1] B. Class 2 air is air with moderate contaminant concentration, mild sensory-irritation intensity or mildly offensive odor (Class 2 air also includes air that is not necessarily harmful or objectionable but that is inappropriate for transfer or recirculation to spaces used for different purposes). Recirculation or transfer of Class 2 air shall be permitted in accordance with Sections 160.2(c)8Bi through 160.2(c)8Bv: i. Recirculation of Class 2 air within the space of origin shall be permitted [ASHRAE 62.1:5.13.3.2.1]. ii. Recirculation or transfer of Class 2 air to other Class 2 or Class 3 spaces shall be permitted, provided that the other spaces are used for the same or similar purpose or task and involve the same or similar pollutant sources as the Class 2 space [ASHRAE 62.1:5.13.3.2.2]; or iii. Transfer of Class 2 air to toilet rooms [ASHRAE 62.1:5.13.3.2.3]; or

  iv. Recirculation or transfer of Class 2 air to Class 4 spaces [ASHRAE 62.1:5.13.3.2.4]. v. Class 2 air shall not be recirculated or transferred to Class 1 spaces. [ASHRAE 62.1:5.13.3.2.5]. Exception to Section 160.2(c)8Bv: When using any energy recovery device, recirculation from leakage, carryover or transfer from the exhaust side of the energy recovery device is permitted. Recirculated Class 2 air shall not exceed 10 percent of the outdoor air intake flow. C. Class 3 air is air with significant contaminant concentration, significant sensory-irritation intensity or offensive odor. Recirculation or transfer of Class 3 air shall be permitted in accordance with Sections 160.2(c)8Ci and 160.2(c)8Cii: i. Recirculation of Class 3 air within the space of origin shall be permitted.

• CMC § 120.1 High relevance — show source text

  **

  1. All mechanical ventilation and space-conditioning systems shall be designed with and have installed ductwork, dampers and controls that allow design minimum outside air rates to be operated at no less than the larger of (1) the minimum levels specified in Section 120.1(c)3; or (2) the rate required for make-up of exhaust systems that are required for a covered or noncovered process, for control of odors, or for the removal of contaminants within the space.
  2. All variable air volume mechanical ventilation and space-conditioning systems shall include dynamic controls that are capable of maintaining measured outside air ventilation rates within 10 percent of the design minimum outside air ventilation rate at both full and reduced supply airflow conditions. Fixed minimum damper position is not considered to be dynamic and is not an allowed control strategy.
  3. All mechanical ventilation and space-conditioning systems shall be tested to confirm their ability to operate within 10 percent of the design minimum outside air rate.

  (g) Air classification and recirculation limitations. Air classification and recirculation limitations of air shall be based on the air classification as listed in Table 120.1-A or Table 120.1-C, and in accordance with the requirements of Sections 120.1(g)1 through 4.

  Note: Air class definitions are taken directly from ASHRAE 62.1 and are duplicated here for convenience.

  1. Class 1 Air is air with low contaminant concentration, low sensory-irritation intensity or inoffensive odor. Recirculation or transfer of Class 1 air to any space shall be permitted; [ASHRAE 62.1:5.13.3.1]

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

  2. Class 2 Air is air with moderate contaminant concentration, mild sensory-irritation intensity or mildly offensive odors (Class 2 air also includes air that is not necessarily harmful or objectionable but that is inappropriate for transfer or recirculation to spaces used for different purposes). Recirculation or transfer of Class 2 air shall be permitted in accordance with Sections 120.1(g)2A through 120.1(g)2E: A. Recirculation of Class 2 air within the space of origin shall be permitted [ASHRAE 62.1:5.13.3.2.1]; B. Recirculation or transfer of Class 2 to other Class 2 or Class 3 spaces shall be permitted, provided that the other spaces are used for the same or similar purpose or task and involve the same or similar pollutant sources as the Class 2 space [ASHRAE 62.1:5.13.3.2.2]; or C. Transfer of Class 2 air to toilet rooms [ASHRAE 62.1:5.13.3.2.3]; or

  D. Recirculation or transfer of Class 2 air to Class 4 spaces [ASHRAE 62.1:5.13.3.2.4]; or E. Class 2 air shall not be recirculated or transferred to Class 1 spaces. [ASHRAE 62.1:5.13.3.2.5] Exception to Section 120.1(g)2E: When using any energy recovery device, recirculation from leakage, carryover, or transfer from the exhaust side of the energy recovery device is permitted.

• CMC § 120.1 High relevance — show source text

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

  2. Class 2 Air is air with moderate contaminant concentration, mild sensory-irritation intensity or mildly offensive odors (Class 2 air also includes air that is not necessarily harmful or objectionable but that is inappropriate for transfer or recirculation to spaces used for different purposes). Recirculation or transfer of Class 2 air shall be permitted in accordance with Sections 120.1(g)2A through 120.1(g)2E: A. Recirculation of Class 2 air within the space of origin shall be permitted [ASHRAE 62.1:5.13.3.2.1]; B. Recirculation or transfer of Class 2 to other Class 2 or Class 3 spaces shall be permitted, provided that the other spaces are used for the same or similar purpose or task and involve the same or similar pollutant sources as the Class 2 space [ASHRAE 62.1:5.13.3.2.2]; or C. Transfer of Class 2 air to toilet rooms [ASHRAE 62.1:5.13.3.2.3]; or

  D. Recirculation or transfer of Class 2 air to Class 4 spaces [ASHRAE 62.1:5.13.3.2.4]; or E. Class 2 air shall not be recirculated or transferred to Class 1 spaces. [ASHRAE 62.1:5.13.3.2.5] Exception to Section 120.1(g)2E: When using any energy recovery device, recirculation from leakage, carryover, or transfer from the exhaust side of the energy recovery device is permitted. Recirculated Class 2 air shall not exceed 10 percent of the outdoor air intake flow. 3. Class 3 Air is air with significant contaminant concentration, significant sensory-irritation intensity or offensive odor. Recirculation or transfer of Class 3 air shall be permitted in accordance with Section 120.1(g)3A and B: A. Recirculation of Class 3 air within the space of origin shall be permitted. [ASHRAE 62.1:5.13.3.3.1] B. Class 3 air shall not be recirculated or transferred to any other space. [ASHRAE 62.1:5.13.3.3.2]. Exception to Section 120.1(g)3B: When using any energy recovery device, recirculation from leakage, carryover, or transfer from the exhaust side of the energy recovery device is permitted. Recirculated Class 3 air shall not exceed 5 percent of the outdoor air intake flow. 4. Class 4 Air is air with highly objectionable fumes or gases or with potentially dangerous particles, bioaerosols, or gases at concentrations high enough to be considered as harmful. Class 4 air shall not be recirculated or transferred to any space or recirculated within the space of origin. [ASHRAE 62.1:5.13.3.4] 5. Ancillary spaces. Redesignation of Class 1 air to Class 2 air shall be permitted for Class 1 spaces that are ancillary to Class 2 spaces. [ASHRAE 62.1:5.13.2.3] 6. Transfer.

• CMC § 62.1 High relevance — show source text

  ii. Recirculation or transfer of Class 2 air to other Class 2 or Class 3 spaces shall be permitted, provided that the other spaces are used for the same or similar purpose or task and involve the same or similar pollutant sources as the Class 2 space [ASHRAE 62.1:5.13.3.2.2]; or iii. Transfer of Class 2 air to toilet rooms [ASHRAE 62.1:5.13.3.2.3]; or

  iv. Recirculation or transfer of Class 2 air to Class 4 spaces [ASHRAE 62.1:5.13.3.2.4]. v. Class 2 air shall not be recirculated or transferred to Class 1 spaces. [ASHRAE 62.1:5.13.3.2.5]. Exception to Section 160.2(c)8Bv: When using any energy recovery device, recirculation from leakage, carryover or transfer from the exhaust side of the energy recovery device is permitted. Recirculated Class 2 air shall not exceed 10 percent of the outdoor air intake flow. C. Class 3 air is air with significant contaminant concentration, significant sensory-irritation intensity or offensive odor. Recirculation or transfer of Class 3 air shall be permitted in accordance with Sections 160.2(c)8Ci and 160.2(c)8Cii: i. Recirculation of Class 3 air within the space of origin shall be permitted. [ASHRAE 62.1:5.13.3.3.1] ii. Class 3 air shall not be recirculated or transferred to any other space. [ASHRAE 62.1:5.13.3.3.2]. Exception to Section 160.2(c)8Cii: When using any energy recovery device, recirculation from leakage, carryover or transfer from the exhaust side of the energy recovery device is permitted. Recirculated Class 3 air shall not exceed 5 percent of the outdoor air intake flow.

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  MULTIFAMILY BUILDINGS—MANDATORY REQUIREMENTS

  D. Class 4 air is air with highly objectionable fumes or gases or with potentially dangerous particles, bioaerosols or gases at concentrations high enough to be considered as harmful. Class 4 air shall not be recirculated or transferred to any space or recirculated within the space of origin. [ASHRAE 62.1:5.13.3.4] E. Ancillary spaces. Redesignation of Class 1 air to Class 2 air shall be permitted for Class 1 spaces that are ancillary to Class 2 spaces. [ASHRAE 62.1:5.13.2.3] F. Transfer. A mixture of air that has been transferred through or returned from spaces or locations with different air classes shall be redesignated with the highest classification among the air classes mixed. [ASHRAE 62.1:5.13.2.2] G. Classification. Air leaving each space or location shall be designated at an expected air-quality classification not less than that shown in Table 160.2-B, 160.2-C or 160.2-D.

• CMC § 160.2 High relevance — show source text

  c. When a single zone damper or a single zone system serves multiple spaces, there shall be an occupant sensor in each space and the zone shall not be considered vacant until all spaces in the zone are vacant. d. One hour prior to normal scheduled occupancy, the occupant sensor ventilation control shall allow preoccupancy purge as described in Section 160.2(c)5B. e. When the zone is scheduled to be occupied and occupant sensing controls in all spaces served by the zone indicate the spaces are unoccupied, the zone shall be placed in occupied-standby mode. f. In 5 minutes or less after entering occupied-standby mode, mechanical ventilation to the zone shall be shut off until the space becomes occupied or until ventilation is needed to provide space heating or conditioning. When mechanical ventilation is shut off to the zone, the ventilation system serving the zone shall reduce the system outside air rate by the amount of outside air required for the zone. g. Where the system providing space conditioning also provides ventilation to the zone, in 5 minutes or less after entering occupied-standby mode, space-conditioning zone setpoints shall be reset in accordance with Section 120.2(e)3. 6. Ducting for zonal heating and cooling units. Where a return plenum is used to distribute outdoor air to a zonal heating or cooling unit that then supplies the air to a space in order to meet the requirements of Section 160.2(c)3, the outdoor air shall be ducted to discharge either: A. Within 5 feet of the unit; or

  B. Within 15 feet of the unit, substantially toward the unit and at a velocity not less than 500 feet per minute. 7. Design and control requirements for quantities of outdoor air . A. All mechanical ventilation and space-conditioning systems shall be designed with and have installed ductwork, dampers and controls to allow outside air rates to be operated at the minimum levels specified in Section 160.2(c)3 or the rate required for make-up of exhaust systems that are required for an exempt or covered process, for control of odors or for the removal of contaminants within the space. B. All variable air volume mechanical ventilation and space-conditioning systems shall include dynamic controls that maintain measured outside air ventilation rates within 10 percent of the required outside air ventilation rate at both full and reduced supply airflow conditions. Fixed minimum damper position is not considered to be dynamic and is not an allowed control strategy. C. Measured outdoor air rates of constant volume mechanical ventilation and space-conditioning systems shall be within 10 percent of the required outside air rate.

  8. Air classification and recirculation limitations. Air classification and recirculation limitations of air shall be based on the air classification as listed in Table 160.2-B or Table 160.2-D, in accordance with the following: A. Class 1 air is air with low contaminant concentration, low sensory-irritation intensity or inoffensive odor. Recirculation or transfer of Class 1 air to any space shall be permitted; [ASHRAE 62.1:5.13.3.1] B. Class 2 air is air with moderate contaminant concentration, mild sensory-irritation intensity or mildly offensive odor (Class 2 air also includes air that is not necessarily harmful or objectionable but that is inappropriate for transfer or recirculation to spaces used for different purposes).

• CMC § 120.1 High relevance — show source text

  Recirculated Class 2 air shall not exceed 10 percent of the outdoor air intake flow. 3. Class 3 Air is air with significant contaminant concentration, significant sensory-irritation intensity or offensive odor. Recirculation or transfer of Class 3 air shall be permitted in accordance with Section 120.1(g)3A and B: A. Recirculation of Class 3 air within the space of origin shall be permitted. [ASHRAE 62.1:5.13.3.3.1] B. Class 3 air shall not be recirculated or transferred to any other space. [ASHRAE 62.1:5.13.3.3.2]. Exception to Section 120.1(g)3B: When using any energy recovery device, recirculation from leakage, carryover, or transfer from the exhaust side of the energy recovery device is permitted. Recirculated Class 3 air shall not exceed 5 percent of the outdoor air intake flow. 4. Class 4 Air is air with highly objectionable fumes or gases or with potentially dangerous particles, bioaerosols, or gases at concentrations high enough to be considered as harmful. Class 4 air shall not be recirculated or transferred to any space or recirculated within the space of origin. [ASHRAE 62.1:5.13.3.4] 5. Ancillary spaces. Redesignation of Class 1 air to Class 2 air shall be permitted for Class 1 spaces that are ancillary to Class 2 spaces. [ASHRAE 62.1:5.13.2.3] 6. Transfer. A mixture of air that has been transferred through or returned from spaces or locations with different air classes shall be redesignated with the highest classification among the air classes mixed. [ASHRAE 62.1:5.13.2.2] 7. Classification. Air leaving each space or location shall be designated at an expected air-quality classification not less than that shown in Tables 120.1-A, 120.1-B or 120.1-C. Air leaving spaces or locations that are not listed in Tables 120.1-A, 120.1-B or 120.1-C shall be designated with the same classification as air from the most similar space or location listed in terms of occupant activities and building construction.

  (h) Ventilation only mechanical systems. HVAC systems without mechanical cooling or mechanical heating shall meet the requirements of Section 120.2(f).

  Note: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code. Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.8, and 25943, Public Resources Code.

  SECTION 120.2—REQUIRED CONTROLS FOR SPACE-CONDITIONING SYSTEMS

  Nonresidential and hotel/motel buildings shall comply with the applicable requirements of Sections 120.2(a) through 120.2(l).

  (a) Thermostatic controls for each zone. The supply of heating and cooling energy to each space-conditioning zone or dwelling unit shall be controlled by an individual thermostatic control that responds to temperature within the zone and that meets the applicable requirements of Section 120.2(b). An energy management control system (EMCS) may be installed to comply with the requirements of one or more thermostatic controls if it complies with all applicable requirements for each thermostatic control.

• CMC § 62.1 Medium relevance — show source text

  Class 3 air shall not be recirculated or transferred to any other space. [ASHRAE 62.1:5.13.3.3.2]. Exception to Section 160.2(c)8Cii: When using any energy recovery device, recirculation from leakage, carryover or transfer from the exhaust side of the energy recovery device is permitted. Recirculated Class 3 air shall not exceed 5 percent of the outdoor air intake flow.

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  MULTIFAMILY BUILDINGS—MANDATORY REQUIREMENTS

  D. Class 4 air is air with highly objectionable fumes or gases or with potentially dangerous particles, bioaerosols or gases at concentrations high enough to be considered as harmful. Class 4 air shall not be recirculated or transferred to any space or recirculated within the space of origin. [ASHRAE 62.1:5.13.3.4] E. Ancillary spaces. Redesignation of Class 1 air to Class 2 air shall be permitted for Class 1 spaces that are ancillary to Class 2 spaces. [ASHRAE 62.1:5.13.2.3] F. Transfer. A mixture of air that has been transferred through or returned from spaces or locations with different air classes shall be redesignated with the highest classification among the air classes mixed. [ASHRAE 62.1:5.13.2.2] G. Classification. Air leaving each space or location shall be designated at an expected air-quality classification not less than that shown in Table 160.2-B, 160.2-C or 160.2-D. Air leaving spaces or locations that are not listed in Table 160.2B, 160.2-C or 160.2-D shall be designated with the same classification as air from the most similar space or location listed in terms of occupant activities and building construction.

  (d) Parking garages. Mechanical ventilation systems for enclosed parking garages in multifamily buildings shall comply with Section 120.6(c).

  Table 160.2-A: Reserved.

  TABLE 160.2-B—MINIMUM OCCUPANT LOAD DENSITY AND VENTILATION RATES FOR MULTIFAMILY COMMON USE AREAS	Col2	Col3	Col4	Col5
  SPACE TYPE	MINIMUM OCCUPANT LOAD DENSITY (p/1000 ft2)1	AREA-BASED MINIMUM VENTILATION Ra (cfm/ft2)	AIR CLASS	NOTES
  Bars, cocktail lounges	33	0.2	2	—
  Break rooms	33	0.15	1	F
  Coffee stations	33	0.15	1	F
  Conference/meeting	33	0.15	1	F
  Corridors	5	0.15	1	F
  Computer (not printing)	5	0.15	1	F
  Daycare (through age 4)	14	0.15	2	—
  Dining rooms	33	0.15	2	—
  Disco/dance floors	100	0.15	2	F
  Freezer and refrigerated spaces (< 50°F)	0	0	2	E
  Game arcades	45	0.

• CMC § 311.1 Medium relevance — show source text

  311.1, 311.3, Chapter 4,

  908.3.2, 932.1, 1105.1,

  E 502.10.2, E 805.0

  Pollution control

  devices. . . . . . . . . . . . . . . . . . . 203.0, 512.3, 512.3.5,

  513.1.1, 513.3.3

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  INDEX

  Recirculation. . . . . . . . . . . . . . . . . . 403.3, 403.5, 403.7,

  403.9, 404.3, 407.4.5, 512.3.5

  Replacement . . . . . . . . . . . . . . . . . . . (see Air, makeup)

  Return . . . . . . . . . . . . . 203.0, 311.0, 402.3, 403.2.2.1.2,

  403.2.2.2.2, 404.3.2, 517.1.2,

  604.4, 905.6, 1105.1, Appendix E

  Supply . . . . . . . . . . 203.0, Chapter 4, 914.5, 1104.2.3.2

  Transfer . . . . . . . . . . . . . . . . . 203.0, 403.7, E 503.4.6.9,

  E 503.4.6.11, E 503.5.11.1,

  E 503.11.2.2, I 801.1.4

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

  Ventilation . . . . . . . . . . . . . . . . . . . . Chapter 4, 701.9.3,

  902.2, 914.5.2, 915.3.1.1,

  925.4, Appendix E

  AIRBORNE INFECTION ISOLATION ROOMS . . . 414.0, 417.0

  Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321.7, 416.0

  AIR CIRCULATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407.4

  AIR CONDITIONED

  Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

  Zone isolation . . . . . . . . . . . . . . . . . . . . . . E 503.4.6.3.4

  AIR CONDITIONING

  Air Conditioning and Heating Systems [OSHPD] . . 320.0

  Appliances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 903.0

• CMC § 120.1 Medium relevance — show source text

  iii. When a single zone serves multiple spaces, there shall be an occupant sensor in each space and the zone shall not be considered vacant until all spaces in the zone are vacant. iv. One hour prior to normal scheduled occupancy, the occupant sensor ventilation control shall allow preoccupancy purge as described in Section 120.1(d)2. v. When the zone is scheduled to be occupied and occupant sensing controls in all spaces served by the zone indicate the spaces are unoccupied, the zone shall be placed in occupied-standby mode. vi. In 5 minutes or less after entering occupied-standby mode, mechanical ventilation to the zone shall be shut off until the space becomes occupied or until ventilation is needed to provide space heating or conditioning. When mechanical ventilation is shut off to the zone, the ventilation system serving the zone shall reduce the system outside air rate by the amount of outside air required for the zone. vii. Where the system providing space conditioning also provides ventilation to the zone, in 5 minutes or less after entering occupied-standby mode, space-conditioning zone setpoints shall be reset in accordance with Section 120.2(e)3.

  (e) Ducting for zonal heating and cooling units. Where a return plenum is used to distribute outdoor air to a zonal heating or cooling unit, which then supplies the air to a space in order to meet the requirements of Section 120.1(c)3, the outdoor air shall be ducted to discharge either:

  1. Within 5 feet of the unit; or

  2. Within 15 feet of the unit, substantially toward the unit, and at a velocity not less than 500 feet per minute.

  (f) Design and control requirements for quantities of outdoor air.

  1. All mechanical ventilation and space-conditioning systems shall be designed with and have installed ductwork, dampers and controls that allow design minimum outside air rates to be operated at no less than the larger of (1) the minimum levels specified in Section 120.1(c)3; or (2) the rate required for make-up of exhaust systems that are required for a covered or noncovered process, for control of odors, or for the removal of contaminants within the space.
  2. All variable air volume mechanical ventilation and space-conditioning systems shall include dynamic controls that are capable of maintaining measured outside air ventilation rates within 10 percent of the design minimum outside air ventilation rate at both full and reduced supply airflow conditions. Fixed minimum damper position is not considered to be dynamic and is not an allowed control strategy.
  3. All mechanical ventilation and space-conditioning systems shall be tested to confirm their ability to operate within 10 percent of the design minimum outside air rate.

  (g) Air classification and recirculation limitations. Air classification and recirculation limitations of air shall be based on the air classification as listed in Table 120.1-A or Table 120.1-C, and in accordance with the requirements of Sections 120.1(g)1 through 4.

  Note: Air class definitions are taken directly from ASHRAE 62.1 and are duplicated here for convenience.

  1. Class 1 Air is air with low contaminant concentration, low sensory-irritation intensity or inoffensive odor. Recirculation or transfer of Class 1 air to any space shall be permitted; [ASHRAE 62.1:5.13.3.1]

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• CMC § 404.3.2 Medium relevance — show source text

  of secondary-recirculation systems include dual-fan dualduct and fan-powered mixing-box systems, and systems that include transfer fans for conference rooms.

  [Equation 404.3.2(1)] Evz = ( Fa+Xs•Fb–Zpz•Ep•Fc )/ Fa

  Where system air fractions Fa, Fb, and Fc are determined in accordance with Equation 404.3.2(2), Equation 404.3.2(3), and Equation 404.3.2(4), as applicable.

  Fa = Ep + (1– Ep )• Er [Equation 404.3.2(2)]

  Fb = Ep [Equation 404.3.2(3)]

  Fc = 1–(1– Ez )•(1– Er )•(1– Ep ) [Equation 404.3.2(4)]

  Where the zone primary air fraction ( Ep ) shall be determined in accordance with Equation 404.3.2(5), zone secondary recirculation fraction ( Er ) shall be determined by the designer based on system configuration, and zone air distribution effectiveness ( Ez ) shall be determined in accordance with Section 403.2.2. [ASHRAE 62.1:A1.2.2]

  Ep = Vpz / Vdz [Equation 404.3.2(5)]

  Where:

  Az = Zone floor area: The net occupiable floor area of the ventilation zone, ft [2] (m [2] ).

  D = Occupant diversity: The ratio of the system population to the sum of the zone populations. Ep = Primary air fraction: The fraction of primary air in the discharge air to the ventilation zone. Er = Secondary recirculation fraction: In systems with secondary recirculation of return air, the fraction of secondary recirculated air to the zone that is representative of average system return air rather than air directly recirculated from the zone. Ev = System ventilation efficiency: the efficiency with which the system distributes air from the outdoor air intake to the breathing zone in the ventilationcritical zone, which requires the largest fraction of outdoor air in the primary airstream. Evz = Zone ventilation efficiency: The efficiency with which the system distributes air from the outdoor air intake to the breathing zone in any particular ventilation zone.

  Ez = Zone air distribution effectiveness: A measure of the effectiveness of supply air distribution to the breathing zone. Ez is determined in accordance with Section 403.2.2.

  Fa = Supply air fraction: The fraction of supply air to the ventilation zone from sources or air outside the

  zone.

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  VENTILATION AIR

  Fb = Mixed air fraction: The fraction of supply air to the ventilation zone from fully mixed primary air.

  Fc = Outdoor air fraction: The fraction of outdoor air to the ventilation zone from sources of air outside

  the zone.

  Ps = System population: the simultaneous number of occupants in the area served by the ventilation sys tem.

• CMC § 404.2 Medium relevance — show source text

  Xs =Vou / Vps (Equation 404.2)

  Where the uncorrected outdoor air intake ( Vou ) is determined in accordance with Section 403.5.1, and the system primary airflow ( Vps ) shall be determined at the condition analyzed. [ASHRAE 62.1:A1.1] 404.3 Zone Ventilation Efficiency. The zone ventilation efficiency ( Evz ) shall be determined in accordance with Section 404.3.1 or Section 404.3.2. [ASHRAE 62.1:A1.2] 404.3.1 Single Supply Systems. For single supply systems, where all of the air supplied to each ventilation zone is a mixture of outdoor air and system-level recirculated air, zone ventilation efficiency ( Evz ) shall be determined in accordance with Equation 404.3.1(1). Examples of single supply systems include constant-volume reheat, single-duct VAV, single-fan dual-duct, and multizone-systems.

  Evz = 1+ Xs – Zpz [Equation 404.3.1(1)]

  Where the average outdoor air fraction for the system ( Xs ) shall be determined in accordance with Equation 404.2 and the primary outdoor air fraction for the zone ( Zpz ) shall be determined in accordance with Equation 404.3.1(2).

  Zpz = Voz/Vpz [Equation 404.3.1(2)]

  For VAV systems, Vpz is the lowest zone primary airflow value expected at the design condition analyzed.

  [ASHRAE 62.1:A1.2.1] 404.3.2 Secondary-Recirculation Systems. For secondary-recirculation systems where the supply air or a portion thereof to each ventilation zone is recirculated air (air that has not been directly mixed with outdoor air) from other zones, zone ventilation efficiency ( Evz ) shall be determined in accordance with Equation 404.3.2(1). Examples

  of secondary-recirculation systems include dual-fan dualduct and fan-powered mixing-box systems, and systems that include transfer fans for conference rooms.

  [Equation 404.3.2(1)] Evz = ( Fa+Xs•Fb–Zpz•Ep•Fc )/ Fa

  Where system air fractions Fa, Fb, and Fc are determined in accordance with Equation 404.3.2(2), Equation 404.3.2(3), and Equation 404.3.2(4), as applicable.

  Fa = Ep + (1– Ep )• Er [Equation 404.3.2(2)]

  Fb = Ep [Equation 404.3.2(3)]

  Fc = 1–(1– Ez )•(1– Er )•(1– Ep ) [Equation 404.3.2(4)]

  Where the zone primary air fraction ( Ep ) shall be determined in accordance with Equation 404.3.2(5), zone secondary recirculation fraction ( Er ) shall be determined by the designer based on system configuration, and zone air distribution effectiveness ( Ez ) shall be determined in accordance with Section 403.2.2. [ASHRAE 62.1:A1.2.2]

• CMC § 403.2.2. Medium relevance — show source text

  D = Occupant diversity: The ratio of the system population to the sum of the zone populations. Ep = Primary air fraction: The fraction of primary air in the discharge air to the ventilation zone. Er = Secondary recirculation fraction: In systems with secondary recirculation of return air, the fraction of secondary recirculated air to the zone that is representative of average system return air rather than air directly recirculated from the zone. Ev = System ventilation efficiency: the efficiency with which the system distributes air from the outdoor air intake to the breathing zone in the ventilationcritical zone, which requires the largest fraction of outdoor air in the primary airstream. Evz = Zone ventilation efficiency: The efficiency with which the system distributes air from the outdoor air intake to the breathing zone in any particular ventilation zone.

  Ez = Zone air distribution effectiveness: A measure of the effectiveness of supply air distribution to the breathing zone. Ez is determined in accordance with Section 403.2.2.

  Fa = Supply air fraction: The fraction of supply air to the ventilation zone from sources or air outside the

  zone.

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  VENTILATION AIR

  Fb = Mixed air fraction: The fraction of supply air to the ventilation zone from fully mixed primary air.

  Fc = Outdoor air fraction: The fraction of outdoor air to the ventilation zone from sources of air outside

  the zone.

  Ps = System population: the simultaneous number of occupants in the area served by the ventilation sys tem.

  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 =

• CMC § 403.6.1 Medium relevance — show source text

  T = 3 v/Vbz (Equation 403.6.1)

  Where:

  T = averaging time period, minutes.

  v = the volume of the ventilation zone where averaging is being applied, ft [3] (m [3] ).

  Vbz = the breathing zone outdoor airflow calculated in accordance with Equation 403.2.1 and design value of the zone population ( Pz ), cubic foot per minute (CFM).

  For SI Units: 1 cubic foot = 0.0283 m [3], 1 cubic foot per minute =

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

  Acceptable design adjustments based on this optional provision including the following:

  (1) Zones with fluctuating occupancy: The zone population ( Pz ) shall be permitted to be averaged over time ( T ).

  (2) Zones with intermittent interruption of supply air: The average outdoor airflow supplied to the breathing zone over time ( T ) shall be not less than the breathing zone outdoor airflow ( Vbz ) calculated using Equation 403.2.1.

  (3) Systems with intermittent closure of the outdoor air intake: The average outdoor air intake over time ( T ) shall be not less than the minimum outdoor air intake ( Vot ) calculated using Equation 403.3, Equation 403.4, or Equation 403.5.1 as applicable.

  [ASHRAE 62.1:6.2.5.2]

  403.7 Exhaust Ventilation. Exhaust airflow shall be provided in accordance with the requirements in Table 403.7. Exhaust makeup air shall be permitted to be a combination of outdoor air, recirculated air, and transfer air.

  403.7.1 Parking Garages. Exhaust rate for parking garages shall be in accordance with Table 403.7. Exhaust rate shall not be required for enclosed parking garages having a floor area of 1000 square feet (92.9 m [2] ) or less and used for the storage of 5 or less vehicles.

  403.7.2 Enclosed Parking Garages. Mechanical ventilation systems for enclosed parking garages shall operate continuously.

  Exceptions:

  (1) Mechanical ventilation systems shall be permitted to operate intermittently where the system is designed to operate automatically upon detection of vehicle operation or the presence of occupants by approved automatic detection devices.

  (2) Approved automatic carbon monoxide sensing devices, and nitrogen dioxide detectors shall be permitted to modulate the ventilation system to not exceed a maximum average of 50 parts per million of carbon monoxide, or 1 part per million nitrogen dioxide during an eight-hour period with a concentration of not more than 200 parts per million for carbon monoxide, or 5 parts per million nitrogen dioxide, for a period not exceeding 15 minutes. Automatic sens

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  VENTILATION AIR

  ing devices installed in modulated parking garage ventilation systems shall be approved in accordance with Section 301.2.

  403.7.2.1 Alternative Exhaust Ventilation for Enclosed Parking Garages.

• CMC § 2.5 Medium relevance — show source text

  (3) Select louvers that are Class A when rated according to AMCA 511 and tested per the AMCA 500-L wind-driven rain test when subjected to a simulated rainfall of 3 inches (76 mm) per hour and a 29 mph (13 m/s) wind velocity. The maximum design core area velocity through the louver shall correlate to a Class A rating.

  (4) Use rain hoods sized for no more than 500 feet per minute (2.5 m/s) face velocity with a downward-facing intake such that all intake air passes upward through a horizontal plane that intersects the solid surfaces of the hood before entering the system.

  (5) Manage the water that penetrates the intake opening by providing a drainage area or moisture removal devices. {ASHRAE 62.1:5.5.2} 402.4.3 Rain Intrusion. Air-handling and distribution equipment mounted outdoors shall be designed to prevent rain intrusion into the airstream when tested at design airflow and with no airflow, using the rain test apparatus described in UL 1995. [ASHRAE 62.1:5.5.3] 402.4.4 Snow Entrainment. Where climate dictates, outdoor air intakes that are part of the mechanical ventilation system shall be designed as follows to manage water from snow that is blown or drawn into the system:

  (1) Access doors to permit cleaning of wetted surfaces shall be provided.

  (2) Outdoor air ductwork or plenums shall pitch to drains designed in accordance with the requirements of ASHRAE 62.1. [ASHRAE 62.1:5.5.4]

  402.4.5 Bird Screens. Outdoor air intakes shall include a screening device designed to prevent penetration by a 0.5 inch (13 mm) diameter probe. The screening device material shall be corrosion resistant. The screening device shall be located, or other measures shall be taken, to prevent bird nesting within the outdoor air intake. [ASHRAE 62.1:5.5.5]

  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)

• 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]

• CMC § 401.1 Medium relevance — show source text

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  CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE

  CHAPTER 4 – VENTILATION AIR

  (Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

  • [>]

  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	BSC	BSC- CG	SFM	HCD	Col6	Col7	DSA	Col9	Col10	OSHPD	Col12	Col13	Col14	Col15	Col16	Col17	BSCC	DPH	AGR	DWR	CEC	CA	SL	SLC
  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.

• CMC § 90.1 Medium relevance — show source text

  [ASHRAE 90.1: TABLE 6.4.3.4.3]

  Col1	OUTDOOR AIR INTAKE (CFM/ft2)	Col3	EXHAUST/RELIEF (CFM/ft2)	Col5
  CLIMATE ZONE	NONMOTORIZED1	MOTORIZED	NONMOTORIZED3	MOTORIZED
  0, 1, 2	0, 1, 2	0, 1, 2	0, 1, 2	0, 1, 2
  Any height	20	4	20	4
  3	3	3	3	3
  Any height	20	10	20	10
  4, 5B, 5C	4, 5B, 5C	4, 5B, 5C	4, 5B, 5C	4, 5B, 5C
  Fewer than three stories	204	10	20	10
  Three or more stories	204	10	204	10
  5A, 6, 7, 8	5A, 6, 7, 8	5A, 6, 7, 8	5A, 6, 7, 8	5A, 6, 7, 8
  Fewer than three stories	204	4	20	4
  Three or more stories	204	4	204	4

  For SI units: 1 square foot = 0.0929 m [2], 1 cubic foot per minute = 0.00047 m [3] /s, 1 cubic foot per minute = 0.4719 L/s, 1 cubic foot per minute per square foot = 5.08 [(L/s)/m [2] ], 1 inch water gauge = 0.249 kPa

  Notes:

  1 When tested in accordance with AMCA 500D.

  2 Dampers smaller than 12 inches (305 mm) in height, width, or diameter need not be tested but shall be of the same design and construction as the smallest tested damper meeting the listed leakage rate requirement.

  3 Nonmotorized dampers smaller than 24 inches (610 mm) in height, width, or diameter shall be permitted to have a leakage rate of 40 CFM/ft 2 [0.203 (m 3 /s)/m 2 ].

  4 Where permitted by Section E 503.4.6.4.1, exception 2.

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  APPENDIX E

  (2) Systems serving zones where humidity levels are required to be maintained with precision of not more than ±5 percent relative humidity to comply with applicable codes or accreditation standards or as approved by the Authority Having Jurisdiction.

  [ASHRAE 90.1:6.4.3.6.2]

• CMC § 1220.4.2 Medium relevance — show source text

  8|1220.4.2 – 1220.4.6| |1221.7|1221.6| |1308.2 – 1308.4.1|1308.3 – 1308.5.1| |Table 1308.3.1|Table 1308.4.1| |1308.4.2|1308.5.2| |1308.4.2.2 – 1308.6.4|1308.5.2.1 – 1308.7.3| |Table 1308.4.6.2|Table 1308.5.6.2| |1308.6.5 – 1308.13.1|1308.7.7 – 1308.14.1| |1312.1.2 – 1312.1.3|1312.1.1 – 1312.1.2| |Chapter 17|Appendix F| |Chapter 18|Chapter 17| |D 103.2|D 103.1| |E 503.5.6.7|E 503.5.6.6| |E 503.5.7.2 – E 503.5.7.6|E 503.5.7.1 – E 503.5.7.5| |Table E 503.5.7.2|Table E 503.5.7.1| |Table E 503.5.7.6|Table E 503.5.7.5| |Table E 503.5.10.1.2(1)|Table E 503.5.10(1)| |Table E 503.5.10.1.2(2)|Table E 503.5.10(2)| |E 503.5.10.1.2|E 503.5.10| |E 503.5.10.2 – E 503.5.10.2.2|E 503.5.10.1 – E 503.5.10.1.2| |E 503.5.12.1|E 503.5.12| |E 503.5.12.2|E 503.5.12.1| |E 503.6.5.4|E 503.6.5.4.1|

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• CMC § 10005-4026. Medium relevance — show source text

  IES Illuminating Engineering Society, 120 Wall St. Fl 17, New York, NY 10005-4026.

  IEST Institute of Environmental Sciences and Technology, 1827 Walden Office Square, Suite 400, Schaumburg, IL 60173.

  IGSHPA International Ground Source Heat Pump Association, 1723 W. Tyler Ave. Stillwater, OK 74078.

  IIAR International Institute of Ammonia Refrigeration, 1001 N. Fairfax Street, Suite 503, Alexandria, VA 22314.

  ISO International Organization for Standardization, 1 ch. de la Voie-Creuse, Casa Postale 56, CH-1211 Geneva 20, Switzerland.

  MSS Manufacturers Standardization Society of the Valve and Fittings Industry, 127 Park Street NE, Vienna, VA 22180.

  NAIMA North American Insulation Manufacturers Association, Inc., 11 Canal Center Plaza #103, Alexandria, VA 22314.

  NEBB National Environmental Balancing Bureau, 8575 Grovemont Circle, Gaithersburg, MD 20877.

  NFPA National Fire Protection Association, 1 Batterymarch Park, Quincy, MA 02169-7471.

  NGWA National Ground Water Association, 601 Dempsey Road, Westerville, Ohio 43081-8978.

  NSF NSF International, 789 N. Dixboro Road, Ann Arbor, MI 48105.

  SAE Society of Automotive Engineers, 400 Commonwealth Drive, Warrendale, PA 15096.

  SMACNA Sheet Metal and Air Conditioning Contractors National Association, 4201 Lafayette Center Drive, Chantilly, VA 20151-1219.

  UL Underwriters Laboratories, Inc., 333 Pfingsten Road, Northbrook, IL 60062.

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  APPENDICES

  The appendices are intended to supplement the provisions of the installation requirements of this code. The definitions in Chapter 2 are also applicable to the appendices.

  TABLE OF CONTENTS

  »

  »

  Appendix A Page

  Residential Plans Examiner Review Form for HVAC System Design..............................................................387

  Appendix B

  Procedures to be Followed to Place Gas Equipment in Operation..................................................................391

  Appendix C

  Installation and Testing of Oil (Liquid) Fuel-Fired Equipment ..........................................................................395

  Appendix D

  Fuel Supply: Manufactured/Mobile Home Parks and Recreational Vehicle Parks ..........................................403

  Appendix E

  Sustainable Practices ......................................................................................................................................411

  Appendix F

  Sizing of Venting Systems and Outdoor Combustion and Ventilation Opening Design ..................................533

  Appendix G

  Example Calculation of Outdoor Air Rate........................................................................................................545

  Appendix H

  Professional Qualifications ..............................................................................................................................549

  Appendix I

  Indoor Horticultural Facilities ..........................................................................................................................553

  Appendix J

  Clean Air Delivery............................................................................................................................................559

  2025 CALIFORNIA MECHANICAL CODE 385

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

  386 2025 CALIFORNIA MECHANICAL CODE

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

• CEC § 403 Medium relevance — show source text

  Appendix D Fuel Supply: Manufactured/Mobile Home Parks and Recreational

  Vehicle Parks . . . . . . . . . . . . . . . . 403

  Appendix E Sustainable Practices . . . . . . . . . . 411

  Appendix F Sizing of Venting Systems and Outdoor Combustion and

  Ventilation Opening Design . . . . . 533

  Appendix G Example Calculation of Outdoor Air Rate. . . . . . . . . . . . . . 545

  Appendix H Professional Qualifications . . . . . . 549

  Appendix I Indoor Horticultural Facilities . . . . 553

  Appendix J Clean Air Delivery. . . . . . . . . . . . . 559

  USEFUL TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . 563

  INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 571

  HISTORY NOTE

  APPENDIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 593

  2025 CALIFORNIA MECHANICAL CODE

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

  CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE

  CHAPTER 1 – ADMINISTRATION

  (Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

  Adopting Agency	BSC	BSC- CG	SFM	HCD	Col6	Col7	DSA	Col9	Col10	OSHPD	Col12	Col13	Col14	Col15	Col16	Col17	BSCC	DPH	AGR	DWR	CEC	CA	SL	SLC
  Adopting Agency	BSC	BSC- CG	SFM	1	2	1-AC	AC	** SS**	** SS/CC**	1	1R	2	3	4	5	6	6	6	6	6	6	6	6	6
  Adopt Entire Chapter
  Adopt Entire Chapter as amended (amended sections listed below)
  Adopt only those sections that are listed below	X	X	X	X	X	X	X	X	X	X	** X**	X	X	X	X	X	X	X	X	X	X	X	X	X
  Chapter/Section
  _Division I

• CEC § 384 Medium relevance — show source text

  384 2025 CALIFORNIA MECHANICAL CODE

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

  APPENDICES

  The appendices are intended to supplement the provisions of the installation requirements of this code. The definitions in Chapter 2 are also applicable to the appendices.

  TABLE OF CONTENTS

  »

  »

  Appendix A Page

  Residential Plans Examiner Review Form for HVAC System Design..............................................................387

  Appendix B

  Procedures to be Followed to Place Gas Equipment in Operation..................................................................391

  Appendix C

  Installation and Testing of Oil (Liquid) Fuel-Fired Equipment ..........................................................................395

  Appendix D

  Fuel Supply: Manufactured/Mobile Home Parks and Recreational Vehicle Parks ..........................................403

  Appendix E

  Sustainable Practices ......................................................................................................................................411

  Appendix F

  Sizing of Venting Systems and Outdoor Combustion and Ventilation Opening Design ..................................533

  Appendix G

  Example Calculation of Outdoor Air Rate........................................................................................................545

  Appendix H

  Professional Qualifications ..............................................................................................................................549

  Appendix I

  Indoor Horticultural Facilities ..........................................................................................................................553

  Appendix J

  Clean Air Delivery............................................................................................................................................559

  2025 CALIFORNIA MECHANICAL CODE 385

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

  386 2025 CALIFORNIA MECHANICAL CODE

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

  CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE

  APPENDIX A – RESIDENTIAL PLAN EXAMINER REVIEW FORM FOR HVAC SYSTEM DESIGN

  (Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

  Adopting Agency	BSC	BSC- CG	SFM	HCD	Col6	Col7	DSA	Col9	Col10	OSHPD	Col12	Col13	Col14	Col15	Col16	Col17	BSCC	DPH	AGR	DWR	CEC	CA	SL	SLC
  Adopting Agency	BSC	BSC- CG	SFM	1	2	1-AC	AC	** SS**	** SS/CC**	1	1R	2	3	4	5	6	6	6	6	6	6	6	6	6
  Adopt Entire Chapter
  Adopt Entire Chapter as amended (amended sections listed below)
  Adopt only those sections that are listed below
  Chapter/Section

• CMC § 403.3 Medium 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.

  2025 CALIFORNIA MECHANICAL CODE 73

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

  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 § 403.2.2.1.3 Medium relevance — show source text

  403.2.2.1.3 Stratification. The zone shall not contain any devices that mechanically mix the air, and shall be protected from impinging airstreams from adjacent ventilation zones.

  [ASHRAE 62.1:6.2.1.2.1.3] 403.2.2.2 Personalized Ventilation Systems. A personalized ventilation system shall be designed in accordance with the following subsections, or the zone air distribution effectiveness ( Ez ) shall be determined in accordance with ASHRAE 62.1.

  [ASHRAE 62.1:6.2.1.2.2] 403.2.2.2.1 Personalized Air. The personalized air shall be distributed in the breathing zone and designed such that the velocity is

  equal to or less than 50 feet per minute (0.25 m/s) at the head/facial region of the occupant.

  [ASHRAE 62.1:6.2.1.2.2.1] 403.2.2.2.2 Return Air. The return air openings or pathways shall be located more than 9 feet (2.8 m) above the floor. [ASHRAE 62.1:6.2.1.2.2.2]

  403.2.3 Zone Outdoor Airflow. The zone outdoor airflow ( Voz ) provided to the ventilation zone by the supply air distribution system shall be determined in accordance with Equation 403.2.3. [ASHRAE 62.1:6.2.1.3]

  Voz = Vbz / Ez (Equation 403.2.3)

  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 )

• CMC § 403.2.1. Medium 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