Ventilation Air

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

• California Mechanical Code High relevance — show source text

  A mechanical code, as with any other code, is intended to be adopted as a legally enforceable document to safeguard health, safety, property, and public welfare. The code cannot be effective without satisfactory provisions for its administration and enforcement. The Authority Having Jurisdiction is to review the proposed and completed work and decide whether a mechanical system conforms to the code requirements. As a public servant, the Authority Having Jurisdiction enforces the code in an unbiased proper manner. The design professional is responsible for the design of a safe mechanical system. The contractor is responsible for installing the system in accordance with the plans.

  Chapter 2 Definitions. To maintain consistency and encourage the use of common terminology, Chapter 2 establishes definitions to provide clarity of terms and promote the use of a common language throughout the code. Understanding definitions within the context of their application enables greater collaboration, efficiency, standardization, and interpretation in applying and enforcing terms used throughout the code. Codes are technical documents, and every term can impact the meaning of the code text. Terms not defined have a normally accepted meaning.

  Chapter 3 General Regulations. Chapter 3 regulates the general requirements, not specific to other chapters, for installing mechanical systems. Many regulations are not specific mechanical requirements but relate to the overall mechanical system. This chapter contains safety requirements for appliance location and installation, appliance and system access, condensate disposal, clearances to combustibles, and return or outside air used in mechanical systems. Listing method of approval, based on applicable nationally recognized standards for the safe and proper installation of mechanical systems, is essential to ensure protection of public health, safety, and welfare. These safety requirements provide protection for piping, tubing, materials, and structures, including provisions for installation practices addressing stress and strain, sleeving, and hanger support. The building’s structural stability is protected by the regulations for cutting and notching of structural members.

  Chapter 4 Ventilation Air. Chapter 4 regulates the minimum requirements for ventilation air supply, exhaust, and makeup air for occupiable spaces within a building. Building ventilation is one important factor affecting the relationship between airborne transmission of respiratory infections and the health and productivity of workers. Ventilation air may be composed of mechanical or natural ventilation, infiltration, recirculated air, transfer air, or a suitable combination of these. Providing a comfortable and healthy indoor environment for building occupants is of primary concern. When determining ventilation rates, typical and unusual significant sources of indoor pollution need to be controlled. Areas such as kitchens, bathrooms, and laundries are all built to allow specific functions. These spaces produce pollutants such as moisture, odors, volatile organic compounds, particles, or combustion byproducts. The purpose of local exhaust is to control concentrates of these pollutants in the room into which they were emitted and to reduce the spread of pollutants into other parts of the occupancy. Local exhaust ventilation is the source control for pollution that is expected in certain rooms. Using local exhaust to extract contaminants before they mix with the indoor environment is essential.

  Chapter 5 Exhaust Systems. Chapter 5 regulates the minimum requirements for exhaust systems. Chapter 5 contains two parts: Part I provides exhaust requirements for environmental air ducts and product conveying systems; Part II provides exhaust requirements for commercial hoods and kitchen ventilation. Environmental air ducts include exhaust ducts used for transporting the air from domestic kitchens, bathrooms, shower rooms, lo

• CMC § 403.0 High 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 § 403.7 High relevance — show source text

  1
  Table 403.7_Notes 11 & 12_
  
  
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  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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  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 High 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_
  
  
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  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.

• CMC § 5.08 Medium 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 § 403.7.1 Medium relevance — show source text

  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.

  403.7.2.2 Minimum Exhaust Rate. [HCD 1 & 2] In lieu of the exhaust rates in Table 403.7, venti- lation systems shall be capable of providing 14,000 cfm (6608 L/s) of exhaust air for each operating vehicle. Number of operating vehicles shall be deter- mined based on 2.5 percent of all parking spaces (and not less than one vehicle).

  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

• CMC § 401.2 Medium relevance — show source text

  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.

  [OSHPD 1, 2, 3, 4 & 5] Health care spaces shall meet the ventilation requirements found in Table 4-A. Ventilation rates for areas not specified in Table 4-A shall have minimum ven- tilation and air change rates per ANSI/ASHRAE Standard 62.1. Where areas with prescribed ventilation rates in both Standards 62.1 and Table 4-A exist, the higher of the two air change rates shall be used.

  402.1.1 Construction Documents. The outdoor air ventilation rate and air distribution assumptions made in the design of the ventilation system shall be clearly identified on the construction documents.

  402.1.2 Ventilation in Health Care Facilities.

  Mechanical ventilation for health care facilities shall be designed and installed in accordance with this code, ASHRAE/ASHE 170, and NFPA 99. [OSHPD 1, 1R, 2, 3, 4 & 5] Ventilation for health care facilities shall be designed and installed in accordance with this code and Table 4-A. All supply-air, return air, and exhaust-air sys- tems shall comply with this code and ASHRAE 170. When the requirements of this code conflict with ASHRAE 170, the most restrictive requirements shall prevail. The text of ASHRAE 170 shall be modified as follows:

  (1) ASHRAE 170. Section 6.1.2.1 -- Also see Section 319.0.

  (2) ASHRAE 170. Section 6.3.1.3 – Modify as follows: Relief air other than class 1 shall discharge at least 10 feet (3048 mm) from any outside air intake.

• CMC § 1.83 Medium relevance — show source text

  w. The requirement that all room air be exhausted directly to outdoors applies only to radiology waiting rooms programmed to hold patients who are waiting for chest x-rays for diagnosis of respiratory disease. x. If the planned space is designated in the organization’s operational plan to be used for both bronchoscopy and gastrointestinal endoscopy, the design parameters for “bronchoscopy, sputum collection, and pentamidine administration” shall be used. y. For single-bed patient rooms using Group D diffusers, a minimum of six total ach shall be provided and calculated based on the volume from finished floor to 6 ft (1.83 m) above the floor. z. See AAMI Standard ST79 [12] for additional information for these spaces. aa. Nurse station pressure relationship and ventilation requirements shall match the area in which it is located. bb. Lower total ach ventilation rates shall be permitted when use of the ASHRAE Standard 62.1 1, Section 6.5, “Exhaust Ventilation,” Performance Compliance Path determines that concentration of the contaminants of concern is lower than the corresponding concentration of interest. In addition to other contaminants of concern required by Standard 62,1 Section 6.5.2, the following contaminants of concern shall be considered for the space and maintained not greater than the concentration level indicated: hydrogen peroxide 1 ppm; glutaraldehyde 0.05 ppm; ethyl alcohol 1000 ppm; isopropyl alcohol 400 ppm. ( Informative Note: Listed concentrations of interest were determined by ACGIH [2001]; see Informative Appendix E.) cc. HD segregated compounding area shall have a differential pressure of -0.01 to -0.03 inches water column in relation to adjacent areas and a minimum of 12 air changes per hour. dd. The requirements for the non-HD segregated compounding area shall meet the minimum requirements for the room which it is located. ee. Informative Note: Parenthetic notations following a space name are references to the relevant California Building Code sections from Chapter 12 . These paragraph references are provided to the user to aid in the application of design requirements. Functions from 1225, 1226, 1227, or 1228 not specifically identi- fied in the table can refer to the appropriate section from 1224. ff. If this space uses unoccupied turndown it shall include time-delay controls such that turndown does not occur for the first 20 minutes after the space becomes unoccupied. ( Informative Note: The 20 minute delay approximates the time required for 90% reduction in airborne contamination at 6 ach, assuming perfect mixing.) gg. Intensive care patient rooms that contain a modular toilet/sink combination unit within the room shall be provided with a minimum of 75 cfm (35.4 Lis) of exhaust directly over the modular toilet/sink combination unit.

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  VENTILATION AIR

  TABLE 4-B

  FILTER EFFICIENCIES FOR CENTRAL VENTILATION AND AIR-CONDITIONING SYSTEMS IN GENERAL ACUTE CARE HOSPITALS, OUTPA- TIENT FACILITIES, LICENSED CLINICS AND ACUTE PSYCHIATRIC HOSPITALS [1] [OSHPD 1, 3 & 5]

• CMC § 0.0283 Medium relevance — show source text

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

  Where:

  Vbz = breathing zone outdoor airflow, per Table 402.1. Az = zone floor area, the net occupiable floor area of the ventilation zone. W S = aggregated width of all single outdoor openings located at the same elevation.

  H S = vertical dimension of the single opening or the least vertical dimension of the openings where there are multiple openings.

  • Volumetric airflow rates used to estimate required openable area are based on the following:

  • Dry-air density of 0.075 lbda/ft [3] (1.2 kgda/m [3] ) at a barometric pressure of 1 atm (101.3 kPa) and an air temperature of 70°F (21°C)

  • Temperature difference between indoors and outdoors of 1.8°F (1°C)

  • Gravity constant of 32.2 ft/s [2] (9.81m/s [2] )

  • Window discharge coefficient of 0.6

  (2) Determine the effect of pressure losses along natural ventilation airflow paths on the resulting flow rates, including inlet openings, air transfer grills, ventilation stacks, and outlet openings during representative conditions of expected natural ventilation system use.

  (3) Quantify natural ventilation airflow rates of identified airflow paths accounting for wind induced and thermally induced driving pressures during representative conditions of expected natural ventilation system use.

  (4) Design to provide outdoor air in quantities sufficient to result in acceptable IAQ as established under Section 403.2.1 or ASHRAE 62.1 during representative conditions of expected natural ventilation system use. {ASHRAE 62.1:6.4.2}

  402.2.3 Control and Accessibility. The means to open required operable openings shall be readily accessible to building occupants whenever the space is occupied. Controls shall be designed to coordinate operation of the natural and mechanical ventilation systems.

  [ASHRAE 62.1:6.4.3]

  402.3 Mechanical Ventilation. [Not permitted for OSHPD 1, 2, 3, 4 & 5] Where natural ventilation is not permitted by this section or the California Building Standards Code, mechanical ventilation systems shall be designed, constructed, and installed to provide a method of supply air and either return air or exhaust air, or both, as applicable. Mechan

  |Col1|TABLE 402.2.1.6(A)(2) MINIMUM OPENABLE AREAS: TWO VERTICALLY SPACED OPENINGS* [ASHRAE 62.

• CMC § 1.11. Medium relevance — show source text

  The state agency does not adopt sections identified by 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.

  12-2 2025 CALIFORNIA BUILDING CODE

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

  12 INTERIOR ENVIRONMENT

  User notes:

  About this chapter: Chapter 12 provides minimum provisions for the interior of buildings—the occupied environment. Ventilation, lighting, and space heating are directly regulated in this chapter and in conjunction with the California Mechanical Code and the California Energy Code . Minimum room size, maximum room-to-room sound transmission and classroom acoustics are set for educational occupancies.

  ICC code development note: Code change proposals to sections preceded by the designation [P] will be considered by a code development committee meting during the 2024 (Group A) Code Development Cycle. All other code change proposals will be considered by a code development committee meeting during the 2025 (Group B) Code Development Cycle.

  SECTION 1201—GENERAL

  1201.1 Scope. The provisions of this chapter shall govern ventilation, temperature control, lighting, yards and courts, sound transmission, enhanced classroom acoustics, interior space dimensions, access to unoccupied spaces, toilet and bathroom requirements and ultraviolet (UV) germicidal irradiation systems associated with the interior spaces of buildings.

  SECTION 1202—VENTILATION

  1202.1 General. Buildings shall be provided with natural ventilation in accordance with Section 1202.5, or mechanical ventilation in accordance with the California Mechanical Code .

  Dwelling units complying with the air leakage requirements of the California Energy Code or ASHRAE 90.1 shall be ventilated by mechanical means in accordance with Section 403 of the California Mechanical Code . Ambulatory care facilities and Group I-2 occupancies shall be ventilated by mechanical means in accordance with Section 407 of the California Mechanical Code .

  1202.2 Roof ventilation. Roof assemblies shall be ventilated in accordance with this section or shall comply with Section 1202.3.

  1202.2.1 Ventilated attics and rafter spaces. Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof framing members shall have cross ventilation for each separate space by ventilation openings protected against the entrance of rain and snow. Blocking and bridging shall be arranged so as not to interfere with the movement of air. An airspace of not less than 1 inch (25 mm) shall be provided between the insulation and the roof sheathing. The net free ventilating area shall be not less than [1] / 150 of the area of the space ventilated. Ventilators shall be installed in accordance with manufacturer’s installation instructions.

  Exception: The net free cross-ventilation area shall be permitted to be reduced to [1] / 300 provided both of the following conditions are met:

• CMC § 408.3 Medium relevance — show source text

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  VENTILATION AIR

  408.3 Filters for Skilled Nursing Facilities, Intermedi- ate Care Facilities, and Correctional Treatment Centers.

  408.3.1 The air ventilation systems for skilled nursing facilities, intermediate care facilities and correctional treatment centers shall have filter bank efficiencies as listed in Table 4-C.

  408.3.2 Airborne infection isolation rooms, protective environment rooms, and sensitive areas in correctional treatment centers shall comply with Section 408.2. 408.4 Filters for Outpatient Facilities.

  408.4.1 The air ventilation systems for outpatient facil- ities shall have filter bank efficiencies as listed in Table 4-B.

  408.5 Filters for Recirculating Room Units.

  408.5.1 Filters for recirculating room units shall comply with Section 407.4.5. Where Table 4-A does not permit air recirculated by means of room units, room units with filtration per Table 4-B are permitted.

  409.0 Ducts. [OSHPD 1, 1R, 2, 3, 4 & 5]

  409.1 Ducts which penetrate construction, intended for X- ray or other radiation protection, shall not impair the effec- tiveness of the protection.

  409.2 Duct linings and their use shall meet the requirements of Chapter 6, California Mechanical Code.

  409.3 The anchorage and supporting structural elements for airducts shall be designed to withstand the lateral forces as required by the California Building Code, Title 24, Part 2.

  410.0 Laboratory Ventilating Systems and Hoods.

  [OSHPD 1, 1R, 2, 3, 4 & 5]

  410.1 Laboratory Ventilating Systems. Laboratory ven- tilating systems shall comply with NFPA 99, as required by Section 1224.4.6.4 of the California Building Code.

  410.2 Exhaust Hoods and Safety Cabinets. Hoods and safety cabinets may be used for normal exhaust of a space pro- vided minimum air change rates are maintained. If air change standards in Table 4-A do not provide sufficient air for proper operation of exhaust hoods and safety cabinets (when in use), supplementary makeup air (filtered and preheated) shall be provided around these units to maintain the required airflow direction and exhaust velocity. Makeup systems for hoods shall be arranged to minimize “short circuiting” of air and to avoid reduction in air velocity at the point of contaminant capture.

  410.3 Laboratory Fume Hoods. Laboratory fume hoods shall meet the following standards:

• CMC § 25218.5 Medium relevance — show source text

  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, 25402.5, 25402.8, and 25943, Public Resources Code.

  SECTION 120.1—REQUIREMENTS FOR VENTILATION AND INDOOR AIR QUALITY

  (a) General requirements.

  1. All occupiable spaces in hotel/motel buildings, and nonresidential buildings other than healthcare facilities shall comply with the applicable requirements of Section 120.1(a) through 120.1(g). Healthcare facilities shall be ventilated in accordance with Chapter 4 of the California Mechanical Code.

  2. The required outdoor air-ventilation rate and the air-distribution system design shall be clearly identified on the plans in accordance with Section 10-103 of Title 24, Part 1. (b) Reserved. (c) Nonresidential and hotel/motel buildings. All occupiable spaces shall meet the requirements of Section 120.1(c)1 and shall also comply with either Section 120.1(c)2 or Section 120.1(c)3.

  3. Air filtration.

  A. Mechanical system types specified in Subsections i, ii and iii below shall be designed to ensure that all recirculated air and all outdoor air supplied to the occupiable space is filtered before passing through any system thermal conditioning components. Air filters shall conform to the requirements of Sections 120.1(c)1B, 120.1(c)1C and 120.1(c)1D.

  i. Mechanical space-conditioning systems that supply air to an occupiable space through ductwork exceeding 10 ft (3 m) in length. ii. Mechanical supply-only ventilation systems and makeup air systems that provide outside air to an occupiable space. iii. The supply side of mechanical balanced ventilation systems, including heat recovery ventilation systems and energy recovery ventilation systems that provide outside air to an occupiable space.

  Exception to Section 120.1(c)1A: For heat recovery ventilators and energy recovery ventilators, the location of the filters required by Section 120.1(c)1A may be downstream of a system thermal conditioning component, provided the system is equipped with ancillary filtration upstream of the system’s thermal conditioning component. B. Air filter efficiency. The filters shall have a designated efficiency equal to or greater than MERV 13 when tested in accordance with ASHRAE Standard 52.2, or a particle size efficiency rating equal to or greater than 50 percent in the 0.30–1.0 μm range, and equal to or greater than 85 percent in the 1.0–3.0 μm range when tested in accordance with AHRI Standard 680; and

  C. Systems shall be equipped with air filters that meet either Subsection i or ii below. i. Nominal 2-inch minimum depth filter(s); or ii. Nominal 1-inch minimum depth filter(s) shall be allowed if the filter(s) are sized according to Equation 120.1-A, based on a maximum face velocity of 150 feet per minute.

  (Equation 120.1-A) A face = Q filter /V face

  Where: