Ventilation rates & outdoor air design

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

• § 150.0 High relevance — show source text

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

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

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

  where:

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

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

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

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

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• § 62.1 High relevance — show source text

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

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

  Where:

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

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

  [ASHRAE 62.1:6.5.1]

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

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

• § 160.2 High relevance — show source text

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

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

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

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

  where:

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

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

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  MULTIFAMILY BUILDINGS—MANDATORY REQUIREMENTS

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

• § 170.2 High relevance — show source text

  Exception 3 to Section 170.2(c)4N2: Any configuration where a DOAS unit provides ventilation air to a downstream fan (a terminal box, air handling unit or other space-conditioning equipment) where the total system airflow can be reduced to ventilation minimum or the downstream fan power is no greater than 0.12 watts per cfm when space temperatures are within the thermostat deadband (at low speed per manufacturer’s literature). 3. DOAS supply and exhaust fans shall have a minimum of three speeds to facilitate system balancing. 4. DOAS with mechanical cooling providing ventilation to multiple zones and operating in conjunction with zone heating and cooling systems shall not use heating or heat recovery to warm supply air above 60°F when representative building loads or outdoor air temperature indicates that the majority of zones requires cooling.

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  MULTIFAMILY BUILDINGS—PERFORMANCE AND PRESCRIPTIVE COMPLIANCE APPROACHES

  O. Exhaust air heat recovery. Fan systems designed to operate to the criteria listed in either Table 170.2-I or Table 170.2-J shall include an exhaust air heat recovery system that meets the following: i. A sensible energy recovery ratio of at least 60 percent or an enthalpy recovery ratio of at least 50 percent for both heating and cooling design conditions. ii. Energy recovery bypass or control to disable energy recovery and to directly economize with ventilation air based on outdoor air temperature limits specified in Table 170.2-G. For energy recovery systems where the transfer of energy cannot be stopped, bypass shall prevent the total airflow rate of either outdoor air or exhaust air through the energy recovery exchanger from exceeding 10 percent of the full design airflow rate. iii. For a DOAS unit and a separate independent space-conditioning system meeting the requirements of Section 170.2(c)4Nia, the design supply fan airflow rate shall be the total airflow of only the DOAS unit. Exception to Section 170.2(c)4Oii : DOAS units with the capability to shut off when a separate independent space-conditioning system meets the economizer requirements specified by Section 170.2(c)4Cia is economizing. Exception 1 to Section 170.2(c)4O : Systems meeting Section 140.9(c) prescriptive requirements for laboratory and factory exhaust systems. Exception 2 to Section 170.2(c)4O : Systems serving spaces that are not cooled and that are heated to less than 60°F.

  Exception 3 to Section 170.2(c)4O : Where more than 60 percent of the outdoor air heating energy is provided from site-recovered energy in Climate Zone 16. Exception 4 to Section 170.2(c)4O : Sensible recovery ratio requirements at heating design conditions are not required for Climate Zone 15. Exception 5 to Section 170.2(c)4O : Sensible recovery ratio requirements at cooling design conditions are not required for Climate Zone 1. Exception 6 to Section 170.2(c)4O : Where the sum of the airflow rates exhausted and relieved within 20 feet of each other is less than 75 percent of the design outdoor airflow rate, excluding exhaust air that is either: i. Used for another energy recovery system; ii. Not allowed by the California Mechanical Code (Title 24, Part 4) for use in energy recovery systems with leakage potential; or iii.

• § 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.

• § 120.1 High relevance — show source text

  4. Demand control ventilation devices.

  A. For each system with demand control ventilation (DCV), CO 2 sensors shall be installed in each room that meets the criteria of Section 120.1(d)3 with no less than one sensor per 10,000 square feet of floor space. When a zone or a space is served by more than one sensor, a signal from any sensor indicating that CO 2 is near or at the setpoint within the zone or space, shall trigger an increase in ventilation. B. CO 2 sensors shall be located in the room between 3 feet and 6 feet above the floor or at the anticipated height of the occupants’ heads. C. Demand ventilation controls shall maintain CO 2 concentrations less than or equal to 600 ppm plus the outdoor air CO 2 concentration in all rooms with CO 2 sensors. Exception to Section 120.1(d)4C: The outdoor air ventilation rate is not required to be larger than the design outdoor air ventilation rate required by Section 120.1(c)3 regardless of CO 2 concentration. D. Outdoor air CO 2 concentration shall be determined by one of the following: i. CO 2 concentration shall be assumed to be 400 ppm without any direct measurement; or ii. CO 2 concentration shall be dynamically measured using a CO 2 sensor located within 4 feet of the outdoor air intake.

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

  E. When the system is operating during hours of expected occupancy, the controls shall maintain system outdoor air ventilation rates no less than R a × A z per Equation 120.1-F for each space with a CO 2 sensor(s), plus the greater of either the exhaust air rate or the rate required by Section 120.1(c)3 for other spaces served by the system. F. CO 2 sensors shall be certified by the manufacturer to be accurate within plus or minus 75 ppm at a 600 and 1000 ppm concentration when measured at sea level and 25°C, factory calibrated and certified by the manufacturer to require calibration no more frequently than once every 5 years. Upon detection of sensor failure, the system shall provide a signal which resets to supply the minimum quantity of outside air to levels required by Section 120.1(c)3 to the zone serviced by the sensor at all times that the zone is occupied. G. The CO 2 sensor(s) reading for each zone shall be displayed continuously, and shall be recorded on systems with DDC to the zone level.

  5. Occupied-standby zone controls. A. Space conditioning zones shall include occupied standby controls complying with Section 120.1(d)5B when all of the following are true: i. All rooms served by the zone are permitted to have their ventilation air reduced to zero while in occupiedstandby mode per Table 120.1-A; and ii. Occupant sensors are required by Sections 130.1(c)5 and 6; and iii. The zone and ventilation system is not served by pneumatic controls. B. Occupied-standby zone controls shall comply with the following: i. Occupant sensors shall have suitable coverage and placement to detect occupants in the entire space. In 20 minutes or less after no occupancy is detected by any sensors covering the room, occupant sensing controls shall indicate a room is vacant.

  ii.

• § 8.2 High relevance — show source text

  2 ft**|Hvs ≤ 8.2 ft|8.2 ft <****Hvs ≤ 16.4 ft|8.2 ft <****Hvs ≤ 16.4 ft|16.4 ft <****Hvs|16.4 ft <****Hvs| |Vbz/Az ≤
  (CFM/ft2)|As/Al
  ≤ 0.5|As/Al
  > 0.5|As/Al
  ≤ 0.5|As/Al
  > 0.5|As/Al
  ≤ 0.5|As/Al
  > 0.5| |0.2|2.0|1.3|1.3|0.8|0.9|0.6| |0.4|4.0|2.6|2.5|1.6|1.8|1.2| |0.6|6.0|3.9|3.8|2.5|2.7|1.7| |0.8|8.0|5.2|5.0|3.3|3.6|2.3| |1.1|11.0|7.1|6.9|4.5|4.9|3.2|

  For SI unit: 1 cubic foot per minute = 0.0283 m [3] /min, 1 cubic foot per minute per square foot = 5.08 [(L/s)/m [2] ], 1 square foot = 0.0929 m [2], 1 foot = 304.8 mm,

  Where:

  Vbz = breathing zone outdoor airflow, per Table 402.1. Az = zone floor area, the net occupiable floor area of the ventilation zone. Hvs = vertical separation between the center of the top and bottom openings’ free operable area; in case of multiple horizontally spaced pairs of openings, use shortest distance encountered. As = openable area of smallest opening (top or bottom); in case of multiple horizontally spaced pairs of top-and-bottom openings, use aggregated areas. Al = openable area of largest opening (top or bottom); in case of multiple horizontally spaced pairs of top-and-bottom openings, use aggregated areas.

  • Volumetric airflow rates used to estimate required operable 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

  ical ventilation systems shall include controls, manual or automatic, that enable the fan system to operate wherever the spaces served are occupied. The system shall be designed to maintain minimum outdoor airflow as required by Section 403.0 under any load conditions.

• § 403.2.2. High 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 =

• § 120.1 High 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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• § 90.1 High relevance — show source text

  (2) Demand ventilation systems on 75 percent or more of the exhaust air. Such systems shall be capable of and configured to provide 50 percent or more reduction in exhaust and replacement air system airflow rates, including controls necessary to modulate airflow in response to appliance operation and to maintain full capture and containment of smoke, effluent, and combustion products during cooking and idle.

  (3) Listed energy recovery devices that result in a sensible energy recovery ratio of 40 percent or more on 50 percent or more of the total exhaust airflow. A 40 percent sensible energy recovery ratio shall mean a change in the dry-bulb temperature of the outdoor air supply equal to 40 percent of the difference between the outdoor air and entering exhaust air dry-bulb temperatures at design conditions. [ASHRAE 90.1:6.5.7.2.3]

  E 503.5.11.2.3 Performance Testing. An approved field test method shall be used to evaluate design air flow rates and demonstrate proper capture and containment performance of installed commercial kitchen exhaust systems. Where demand ventilation systems are utilized

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  APPENDIX E

  «

  E 503.5.12.2 Heating Enclosed Spaces. Radiant heating systems that are used as primary or supplemental heating for enclosed spaces shall be in conformance with the governing provisions of the standard, including, but not limited to the following:

  (1) Radiant hydronic ceiling or floor panels (used for heating or cooling).

  (2) Combination or hybrid systems incorporating radiant heating (or cooling) panels.

  (3) Radiant heating (or cooling) panels used in conjunction with other systems such as VAV or thermal storage systems. [ASHRAE 90.1:6.5.8.2] E 503.5.13 Hot Gas Bypass Limitation. Cooling systems shall not use hot gas bypass or other evaporator pressure control systems unless the system is designed with multiple steps of unloading or continuous capacity modulation. The capacity of the hot gas bypass shall be limited as indicated in Table E 503.5.13 for VAV units and single-zone VAV units. Hot-gas bypass shall not be used on constant-volume units. [ASHRAE 90.1:6.5.9]

  TABLE E 503.5.13

  HOT GAS BYPASS LIMITATION

  [ASHRAE 90.1: TABLE 6.5.9]

  RATED CAPACITY	MAXIMUM HOT GAS BYPASS (percent of total capacity)
  ≤240 000 Btu/h	15%
  >240 000 Btu/h	10%

  For SI units: 1000 British thermal units per hour = 0.293 kW

  E 503.5.14 Door Switches. Conditioned spaces with doors, including doors with more than one-half glass, opening to the outdoors shall be provided with controls that when any such door is open, the following shall occur:

  (1) Disable mechanical heating or reset the heating setpoint to 55°F (13°C) or lower within five minutes of the door opening.

• § 120.1 High relevance — show source text

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

  [ASHRAE 62.1:6.5.1]

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

  TABLE 120.1-A—MINIMUM VENTILATION RATES	Col2	Col3	Col4	Col5
  OCCUPANCY CATEGORY	MINIMUM OCCUPANT LOAD DENSITY (persons/1,000 ft2)	AREA-BASED MINIMUM VENTILATION_ Ra_ (cfm/ft2)	AIR CLASS	NOTES
  Educational Facilities	Educational Facilities	Educational Facilities	Educational Facilities	Educational Facilities
  Daycare (through age 4)	14	0.15	2	—
  Daycare sickroom	5	0.15	3	—
  Classrooms (ages 5–8)	25	0.15	1	—
  Classrooms (age 9–18)	25	0.15	1	—
  Lecture/postsecondary classroom	25	0.15	1	F
  Lecture hall (fixed seats)	-71	0.15	1	F
  Art classroom	25	0.15	2	—
  Science laboratories	25	0.15	2	—
  University/college laboratories	25	0.15	2	—
  Wood/metal shop	10	0.15	2	—
  Computer lab	25	0.15	1	—
  Media center	25	0.15	1	A
  Music/theater/dance	33	0.15	1	F
  Multiuse assembly	33	0.15	1	F
  Food and Beverage Service	Food and Beverage Service	Food and Beverage Service	Food and Beverage Service	Food and Beverage Service
  Restaurant dining rooms	33	0.15	2	—
  Cafeteria/fast-food dining	33	0.15	2	—
  Bars, cocktail lounges	33	0.20	2	—
  Kitchen (cooking)	3	0.

• § 140.4 High relevance — show source text

  4-K represent the design supply fan airflow rate in cfm.
  2.
  For a DOAS unit providing outdoor air to another space-conditioning system, the full design supply fan airflow rate shall be the total airflow of only the DOAS unit.|1.
  Flow rates in Table 140.4-K represent the design supply fan airflow rate in cfm.
  2.
  For a DOAS unit providing outdoor air to another space-conditioning system, the full design supply fan airflow rate shall be the total airflow of only the DOAS unit.|1.
  Flow rates in Table 140.4-K represent the design supply fan airflow rate in cfm.
  2.
  For a DOAS unit providing outdoor air to another space-conditioning system, the full design supply fan airflow rate shall be the total airflow of only the DOAS unit.|1.
  Flow rates in Table 140.4-K represent the design supply fan airflow rate in cfm.
  2.
  For a DOAS unit providing outdoor air to another space-conditioning system, the full design supply fan airflow rate shall be the total airflow of only the DOAS unit.|1.
  Flow rates in Table 140.4-K represent the design supply fan airflow rate in cfm.
  2.
  For a DOAS unit providing outdoor air to another space-conditioning system, the full design supply fan airflow rate shall be the total airflow of only the DOAS unit.|1.
  Flow rates in Table 140.4-K represent the design supply fan airflow rate in cfm.
  2.
  For a DOAS unit providing outdoor air to another space-conditioning system, the full design supply fan airflow rate shall be the total airflow of only the DOAS unit.|

  (r) DDC controller logic using ASHRAE Guideline 36. HVAC systems with DDC controllers shall use controller logic originating from a programming library based on sequences of operation from ASHRAE Guideline 36 in accordance with the following:

  1. Requirement applies to all controllers that are capable of being programmed in the field; and
  2. Requirement applies to the entirety or all applicable portions of equipment control for configurations included in the programming library; and
  3. The programming library shall be certified to the Energy Commission as meeting the requirements of Reference Joint Appendix JA18. Exception to Section 140.4(r)3: Nonprogrammable (configurable-only) controllers for zone terminal units shall follow applicable ASHRAE Guideline 36 zone sequences referenced in Reference Joint Appendix JA18, Table 18.3-1, but are not subject to certification requirements.

  Exception 1 to Section 140.4(r): Logic from the certified programming library modified to suit application-specific operations that are not included in ASHRAE Guideline 36 sequences.

  Exception 2 to Section 140.4(r): Systems serving healthcare facilities.

  128 2025 CALIFORNIA ENERGY CODE

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

  NONRESIDENTIAL AND HOTEL/MOTEL OCCUPANCIES—PERFORMANCE AND PRESCRIPTIVE

  COMPLIANCE APPROACHES FOR ACHIEVING ENERGY EFFICIENCY

  (s) Mechanical heat recovery.

  1. Simultaneous mechanical heat recovery. A. Simultaneous mechanical heat recovery is required for newly constructed buildings that meet either i or ii: i. CHL + 0.1 × CLL ≥ 200 tons and SWHCAP + HCAP ≥ 2200 kBtuh; or