Ventilation, outdoor air and indoor air quality (IAQ)

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

• CRC § 605.0 High relevance — show source text

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

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  APPENDIX E

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

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

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

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

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

  Where:

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

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

  per minute = 0.4719 L/s

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

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

• CRC § 603.1.3 Medium relevance — show source text

  Exception: Other means of reducing the contaminant concentration levels shall be permitted where approved by the Authority Having Jurisdiction. E 603.1.3 Covering of Duct Openings and Pro- tection of Mechanical Equipment During Con- struction. At the time of rough installation, or during storage on the construction site and until final startup of the heating and cooling equipment, duct and other related air distribution component openings shall be covered

  with tape, plastic, sheet metal, or other methods acceptable to the Authority Having Jurisdiction to reduce the amount of dust or debris that collects in the system.

  E 603.2 Isolation of Pollutant Sources. Rooms where activities produce hazardous fumes or chemicals, including commercial kitchens, garages, janitorial or laundry rooms, and copy or printing rooms, shall be exhausted and isolated from adjacent spaces in accordance with this code.

  E 603.3 Filters. In mechanically ventilated buildings, particle filters, or air-cleaning devices shall be provided to clean outdoor and return air prior to its delivery to occupied spaces. The particle or air cleaner shall have a MERV of 13.

  Exception: A filter or air cleaning device with a lower MERV value shall be permitted provided it is the highest value commercially available for the specific equipment that is installed.

  E 603.4 Ozone Depletion and Global Warming Reductions. Installations of HVAC and refrigeration shall not contain CFCs and shall be in accordance with this code.

  E 604.0 Indoor Moisture Control.

  E 604.1 Rainwater Control. Roof drainage systems shall discharge to a place of disposal in accordance with the plumbing code. Storm water shall be directed away from the building.

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

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  APPENDIX E

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

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

• California Mechanical Code Medium 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

• CRC § 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

• CMC § 2025 Medium relevance — show source text

  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, locker rooms, janitor’s closets, and clothes dryers. Systems that carry nonabrasive exhaust, such as smoke, moderate abrasives such as sawdust, and high abrasives such as manganese or acid vapors use product-conveying ducts. Part II provides the minimum fire safety requirements related to the design, installation, inspection, and maintenance of grease-type operations, such as cooking, for both fuel-gas and solid fuel. Cooking produces a significant amount of smoke, fumes, vapors, heat, and other pollutants. Therefore, acceptable kitchen ventilation is necessary to prevent fires from the build-up of grease and to provide the occupants protection from smoke, unpleasant odors, pollutants, and dangerous gases. There are two types of exhaust hoods (Type I and Type II) used in commercial kitchen applications.

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  FORMAT OF THE UNIFORM MECHANICAL CODE

  Type I hoods are intended to be installed above equipment or appliances that generate grease or smoke. Type II hoods are intended to be installed above equipment or appliances that generate steam, vapor, heat, or odors and do not generate grease or smoke.

  Chapter 6 Duct Systems. Chapter 6 regulates requirements for ducts and plenums that are portions of a heating, cooling, ventilation, or exhaust system. This chapter contains material and installation requirements for metal, gypsum, factory-made, flexible, and plastic ducts. It also contains provisions for duct insulation, dampers, fire protection, and automatic shutoff for the building’s air distribution system. It is worth noting that exhaust ducts are regulated by Chapter 5, and combustion air ducts are regulated by Chapter 7.

• CRC § 403.7 Medium 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.

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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.

• CRC § 160.2 Medium relevance — show source text

  Use of Table 160.2-H is limited to ventilation systems that conform to all of the following three specifications: A. Total duct length is less than or equal to 25 feet (8 m), B. Duct system has no more than three elbows, and C. Duct system has exterior termination fitting with a hydraulic diameter greater than or equal to the minimum duct diameter and not less than the hydraulic diameter of the fan outlet. f. Sound ratings for local mechanical exhaust . Local mechanical exhaust systems shall be rated for sound in accordance with Section 7.3 of ASHRAE 62.2 at no less than the minimum airflow rate required by Section 160.2(b)2Avi. Exception to Section 160.2(b)2Avif: Kitchen range hoods may be rated for sound at a static pressure determined at working speed as specified in HVI 916 Section 7.2. vii. Airflow measurement of whole-dwelling unit ventilation . The airflow required by Section 160.2(b)2Aiv or 160.2(b)2Av is the quantity of outdoor ventilation air supplied or indoor air exhausted by the mechanical ventilation system as installed and shall be measured by using a flow hood, flow grid or other airflow measuring device at the mechanical ventilation fan’s inlet terminals/grilles or outlet terminals/grilles in accordance with the procedures in Reference Appendix Section RA3.7.4.1.1 or NA2.2.4.1.1 as applicable for supply and exhaust systems or RA3.7.4.1.2 or NA2.2.4.1.2 as applicable for balanced systems. Balanced mechanical ventilation system airflow shall be the average of the supply fan and exhaust fan flows. viii. Sound ratings for whole-dwelling unit ventilation systems. Whole-dwelling unit ventilation systems shall be rated for sound in accordance with Section 7.2 of ASHRAE 62.2 at no less than the minimum airflow rate required by Section 160.2(b)2Aiv or 160.2(b)2Av as applicable. ix. Label for whole-dwelling unit ventilation system on-off control . Compliance with ASHRAE 62.2 Section 4.4 (Control and Operation) shall require manual ON-OFF control switches associated with whole-dwelling unit ventilation systems to have a label clearly displaying the following text, or equivalent text: “This switch controls the indoor air quality ventilation for the home. Leave switch in the ‘on’ position at all times unless the outdoor air quality is very poor.” x. Combustion air and compensating outdoor air or makeup air. a. All dwelling units shall conform to the applicable requirements specified in California Mechanical Code Chapter 7, Combustion Air. b. All dwelling units shall conform to the requirements in ASHRAE 62.2 Section 6.4, Combustion and SolidFuel-Burning Appliances. xi. Balanced and supply ventilation component accessibility. Balanced and supply ventilation systems shall meet the following requirements for accessibility: a. IAQ filter and HRV/ERV accessibility. System air filters and HRV/ERV heat/energy recovery cores shall be located such that they are accessible for service from within occupiable spaces, basements, garages, balconies, mechanical closets or accessible rooftops. Filters and heat/energy recovery cores behind access panels, access doors, or grilles located no more than 10 feet above a walking surface inside a space specified above comply with this requirement.

• CRC § 6.8 Medium relevance — show source text

  Solar water-heating systems and collectors shall be certified and rated by the Solar Rating and Certification Corporation (SRCC), the International Association of Plumbing and Mechanical Officials, Research and Testing (IAPMO R&T), or by a listing agency that is approved by the executive director. 3. Instantaneous water heaters with an input rating greater than 6.8 kBTU/hr (2kW) shall meet the requirements of Section 110.3(c)6.

  (o) Requirements for ventilation and indoor air quality. All dwelling units shall meet the requirements of ASHRAE Standard 62.2. Ventilation and Acceptable Indoor Air Quality in Residential Buildings subject to the amendments specified in Section 150.0(o)1 below. All dwelling units shall comply with Section 150.0(o)2 below.

  Exception to Section 150.0(o): The following sections of ASHRAE 62.2 shall not be required for compliance: Section 4.1.1, Section 4.1.2, Section 4.1.4, Section 4.3, Section 4.6, Section 5, Section 6.1.1, Section 6.1.3 and Normative Appendix A.

  1. Amendments to ASHRAE 62.2 requirements. A. Window operation. Window operation is not a permissible method of providing the dwelling unit ventilation airflow specified in Section 150.0(o)1C below. B. Central fan integrated (CFI) ventilation systems. CFI ventilation systems shall meet the following requirements. i. Continuous operation prohibition. Continuous operation of a dwelling unit’s central forced air system air handlers used in CFI ventilation systems is not a permissible method of providing the whole-dwelling unit ventilation airflow required in Section 150.0(o)1C. ii. Outdoor air damper(s) . A motorized damper(s) shall be installed on the connected ventilation duct(s) of CFI systems that prevents all airflow into or out of the space-conditioning duct system when the damper(s) is closed.

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

• CRC § 62.2 Medium relevance — show source text

  Local exhaust fans shall be permitted to be part of a mechanical exhaust system. Where local exhaust fans are used to provide dwelling-unit ventilation, the local exhaust airflow shall be permitted to be credited toward the dwelling-unit ventilation airflow requirement. Outdoor air ducts connected to the return side of an air handler shall be permitted as supply ventilation where manufacturer’s requirements for return air temperature are met. See ASHRAE Indoor Air Quality Guide for guidance on selection of methods. [ASHRAE 62.2:4.2] E 605.1.5 Airflow Measurement. The airflow required by this section shall be the quantity of outdoor ventilation air supplied and/or indoor air exhausted by the mechanical ventilation system as installed and shall be measured according to the ventilation equipment manufacturer’s installation instructions, or by using a flow hood, flow grid, or other airflow measuring device at the mechanical ventilation fan’s inlet terminals/grilles, outlet terminals/grilles, or in the connected ventilation ducts. Balanced mechanical ventilation system airflow shall be the average of the supply fan and exhaust fan flows. Ventilation airflow of systems with multiple operating modes shall be tested in all modes designed to meet this section.

  [ASHRAE 62.2:4.3] E 605.1.6 Control and Operation. A readily accessible manual ON-OFF control, including but not limited to a fan switch or a dedicated branch-circuit overcurrent device, shall be provided. Controls shall include text or an icon indicating the system’s function.

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  APPENDIX E

  For the purposes of calculating average relative exposure, a dwelling unit shall be permitted to be treated as unoccupied during a time step only if it is unoccupied for the entire time step. [ASHRAE 62.2:4.5.3] E 605.1.8 Equivalent Ventilation. A dwelling-unit ventilation system shall be designed and operated in such a way as to provide the same or lower annual exposure as would be provided in accordance with Section E 605.1.3. The calculations shall be based on a single zone with a constant contaminant emission rate. The manufacturer, specifier, or designer of the equivalent ventilation system shall certify that the system is in accordance with this intent and provide supporting documentation.

  [ASHRAE 62.2:4.6] E 605.2 Bathroom Exhaust Fans. Except where a whole house energy recovery system is used, a mechanical exhaust fan vented to the outdoors shall be provided in each room containing a bathtub, shower, or tub/shower combination. The ventilation rate shall be not less than 50 ft [3] /min (0.02 m [3] /s) for intermittent operation and 20 ft [3] /min (0.009 m [3] /s) for continuous operation. Fans shall comply with the Energy Star Program.

  E 605.3 Filters. Heating and air conditioning filters shall have a MERV rating of 6 or higher. The air distribution system shall be designed for the pressure drop across the filter.

  E 606.0 Indoor Air Quality for Other than Low-Rise Residential Buildings.

  E 606.1 Minimum Indoor Air Quality. The building shall comply with Chapter 4 or ASHRAE 62.1 for ventilation air supply.

  E 607.0 Environmental Comfort.

• CRC § 160.2 Medium relevance — show source text

  a. Designers shall specify a design ventilation airflow rate for each dwelling unit that is equal to or greater than the rate specified by Equation 160.2-B. b. The design ventilation airflow rate for each dwelling unit shall be stated on the building design plans approved by the enforcement agency. c. Airflow in each dwelling unit shall be no more than 20 percent greater than the specified design ventilation airflow rate. Ventilation systems shall utilize mechanical or software airflow control means to ensure each of the dwelling-unit airflows can be maintained at the design ventilation airflow within this tolerance at all times. System airflow control-means may include but are not limited to constant air regulation devices, orifice plates and variable speed central fans. vi. Local mechanical exhaust. A local mechanical exhaust system shall be installed in each kitchen and bathroom. Systems shall be rated for airflow in accordance with ASHRAE 62.2 Section 7.1. a. Nonenclosed kitchens shall have a demand-controlled mechanical exhaust system meeting the requirements of Section 160.2(b)2Avic. b. Enclosed kitchens and all bathrooms shall have either one of the following options 1 or 2:

  1. A demand-controlled mechanical exhaust system meeting the requirements of Section 160.2(b)2Avic; or

  2. A continuous mechanical exhaust system meeting the requirements of Section 160.2(b)2Avid. c. Demand-controlled mechanical exhaust. A local mechanical exhaust system shall be designed to be operated as needed.

  3. Control and operation. Demand-controlled mechanical exhaust systems shall be provided with at least one of the following controls: A. A readily accessible occupant-controlled ON-OFF control. B. An automatic control that does not impede occupant ON control.

  4. Ventilation rate and capture efficiency. The system shall meet or exceed either the minimum airflow in accordance with Table 160.2-E or the minimum capture efficiency in accordance with Table 160.2-E, and Table 160.2-G. Capture efficiency ratings shall be determined in accordance with ASTM E3087, and listed in a product directory approved by the Energy Commission. d. Continuous mechanical exhaust. A mechanical exhaust system shall be installed to operate continuously. The system may be part of a balanced mechanical ventilation system.

  5. Control and operation . A manual ON-OFF control shall be provided for each continuous mechanical exhaust system. The system shall be designed to operate during all occupiable hours. For multifamily dwelling units, the manual ON-OFF control may be accessible to the dwelling unit occupant; however, the manual ON-OFF control shall not be required to be accessible to the dwelling unit occupant.

  6. Ventilation rate. The minimum delivered ventilation shall be at least the amount indicated in Table 160.2-F during each hour of operation. e. Airflow measurement of local mechanical exhaust by the system installer. The airflow required by Section 160.2(b)2Avi is the quantity of indoor air exhausted by the ventilation system as installed in the dwelling unit. When a vented range hood utilizes a capture efficiency rating to demonstrate compliance with Section 160.2(b)2Avic2, the airflow listed in the approved directory corresponding to the compliant capture efficiency rating point shall be met by the installed system. The as-installed airflow shall be verified by the system installer to ensure compliance by use of either Subsection 1 or 2 below:
• CRC § 2.1 Medium relevance — show source text

  Exception: The glazed areas shall not be required where artificial light and a local exhaust system are provided. The minimum local exhaust rates shall be 50 cubic feet per minute (25 L/s) for intermittent ventilation or 20 cubic feet per minute (10 L/s) for contin- uous ventilation in accordance with the California Mechanical Code, Chapter 4 . Exhaust air from the space shall be exhausted directly to the outdoors.

  R325.2.1 Bathroom exhaust fans. Each bathroom containing a bathtub, shower or tub/shower combination shall be mechanically ventilated for purposes of humidity control in accordance with the California Mechanical Code, Chapter 4; and the California Green Building Standards Code, Chapter 4, Division 4.5.

  Note: Window operation is not a permissible method of providing bathroom exhaust for humidity control.

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  BUILDING PLANNING

  R325.3 Ventilation. Ventilation air rates shall be in compliance with the California Mechanical Code.

  R325.4 Opening location. Outdoor intake and exhaust openings shall be located in accordance with Sections R325.4.1 and R325.4.2.

  R325.4.1 Intake openings. Mechanical and gravity outdoor air intake openings shall be located not less than 10 feet (3048 mm) from any hazardous or noxious contaminant, such as vents, chimneys, plumbing vents, streets, alleys, parking lots and loading docks.

  For the purpose of this section, the exhaust from dwelling unit toilet rooms, bathrooms and kitchens shall not be considered as hazardous or noxious.

  Exceptions:

  1. The 10-foot (3048 mm) separation is not required where the intake opening is located 3 feet (914 mm) or greater below the contaminant source.

  2. Vents and chimneys serving fuel-burning appliances shall be terminated in accordance with the applicable provisions of the California Mechanical Code.

  3. Clothes dryer exhaust ducts shall be terminated in accordance with the California Mechanical Code.

  R325.4.2 Exhaust openings. Exhaust air shall not be directed onto walkways.

  R325.5 Outside opening protection. Air exhaust and intake openings that terminate outdoors shall be protected with corrosionresistant screens, louvers or grilles having an opening size of not less than [1] / 4 inch (6 mm) and a maximum opening size of [1] / 2 inch (13 mm), in any dimension. Openings shall be protected against local weather conditions. Outdoor air exhaust and intake openings shall meet the provisions for exterior wall opening protectives in accordance with this code.

  R325.6 Interior stairway illumination. Interior stairways shall be provided with an artificial light source to illuminate the landings and treads. The light source shall be capable of illuminating treads and landings to levels of not less than 1 footcandle (11 lux) as measured at the center of treads and landings. There shall be a wall switch at each floor level to control the light source where the stairway has six or more risers.

  Exception: A switch is not required where remote, central or automatic control of lighting is provided.

• CRC § 150.0 Medium relevance — show source text

  Filters and heat/energy cores behind access panels, access doors, or grilles located not more than 10 feet above a walking surface inside a space specified above comply with this requirement. Exception to Section 150.0(o)1Civa: Systems that require servicing from inside the attic shall have the following:

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

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

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

  2025 CALIFORNIA ENERGY CODE 171

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

  SINGLE-FAMILY RESIDENTIAL BUILDINGS— MANDATORY FEATURES AND DEVICES

  D. Air filtration. Air filtration shall conform to the specifications in Section 150.0(m)12. Compliance with ASHRAE 62.2 Sections 6.7 (Minimum Filtration) and 6.7.1 (Filter Pressure Drop) shall not be required.

  E. Reserved.

  F. Reserved.

  G. Local mechanical exhaust. A local mechanical exhaust system shall be installed in each kitchen and bathroom. Systems shall be rated for airflow in accordance with ASHRAE 62.2 Section 7.1. i. Nonenclosed kitchens shall have a demand-controlled mechanical exhaust system meeting the requirements of Section 150.0(o)1Giii. ii. Enclosed kitchens and all bathrooms shall have either one of the following alternatives a or b: a. A demand-controlled mechanical exhaust system meeting the requirements of Section 150.0(o)1Giii. b. A continuous mechanical exhaust system meeting the requirements of Section 150.0(o)1Giv. iii. Demand-controlled mechanical exhaust. A local mechanical exhaust system shall be designed to be operated as needed.

  a. Control and operation. Demand-controlled mechanical exhaust systems shall be provided with at least one of the following controls:

  1. A readily accessible occupant-controlled ON-OFF control.
  2. An automatic control that does not impede occupant ON control. b. Ventilation rate and capture efficiency. The system shall meet or exceed either the minimum airflow in accordance with Table 150.0-E or the minimum capture efficiency in accordance with Table 150.0-E, and Table 150.0-G. Capture efficiency ratings shall be determined in accordance with ASTM E3087 and listed in a product directory approved by the Energy Commission.