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.
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.
Where:
Aface = air filter face area, the product of air filter nominal length × nominal width, ft2
Qfilter = design airflow rate for the air filter, ft3/min
Vface = air filter face velocity £ 150, ft/min
Naturally ventilated spaces shall be designed in accordance with 120.1(c)2A through 120.1(c)2C and include a mechanical ventilation system designed in accordance with 120.1(c)3:
EXCEPTION to Section 120.1(c)2Aiv: For ceilings that are increasing in height as distance from the opening is increased, the ceiling height shall be determined as the average height of the ceiling within 20 feet from the operable openings. [ASHRAE 62.1:6.4.1.4]
EXCEPTION 1 to Section 120.1(c)2: The mechanical ventilation system shall not be required where natural ventilation openings complying with 120.1(c)2 are either permanently open or have controls that prevent the openings from being closed during periods of expected occupancy.
EXCEPTION 2 to Section 120.1(c)2: The mechanical ventilation system shall not be required where the zone is not served by a space conditioning system.
Occupiable spaces shall be ventilated with a mechanical ventilation system capable of providing an outdoor airflow rate to the zone (Vz) no less than Equation 120.1-F as described below:
Where:
Rt = Total outdoor airflow rate required per unit area as determined from Table 120.1-A.
Az = Zone floor area, meaning the net occupiable floor area of the ventilation zone in square feet.
Where:
Rp = 15 cubic feet per minute of outdoor airflow per person
Pz = The expected number of occupants. The expected number of occupants shall be the expected number specified by the building designer. For spaces with fixed seating, the expected number of occupants shall be determined in accordance with the California Building Code.
Ra = The minimum ventilation airflow rate allowed for DCV in Table 120.1-A. If Ra is not defined for an occupancy category, Ra = 0.
Az = Zone floor area, meaning the net occupiable floor area of the ventilation zone in square feet.
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]
EXCEPTION 1 to Section 120.1(d)1: Demand control ventilation. In intermittently occupied spaces that do not have processes or operations that generate dusts, fumes, mists, vapors or gasses and are not provided with local exhaust ventilation (such as indoor operation of internal combustion engines or areas designated for unvented food service preparation), the rate of outdoor air may be reduced if the ventilation system serving the space is controlled by a demand control ventilation device complying with Section 120.1(d)4 or by an occupant sensor ventilation control device complying with Section 120.1(d)5.
EXCEPTION 2 to Section 120.1(d)1: Temporary reduction. The rate of outdoor air provided to a space may be reduced below the level required by Section 120.1(c) for up to 30 minutes at a time if the average rate for each hour is equal to or greater than the required ventilation rate.
EXCEPTION 1 to Section 120.1(d)3: Where space exhaust is greater than the design ventilation rate specified in Section 120.1(c)3 minus 0.2 cfm per ft² of conditioned area.
EXCEPTION 2 to Section 120.1(d)3: Spaces that have processes or operations that generate dusts, fumes, mists, vapors, or gases and are not provided with local exhaust ventilation, such as indoor operation of internal combustion engines or areas designated for unvented food service preparation, daycare sickrooms, science labs, barber shops or beauty and nail salons shall not install demand control ventilation.
EXCEPTION 3 to Section 120.1(d)3: Spaces with an area of less than 150 square feet, or a design occupancy of less than 10 people as specified by Section 120.1(c)3.
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 CO2 concentration.
Occupant sensing or ventilation controls are required for space conditioning zones that are both permitted to have their ventilation air reduced to zero while in occupied standby mode per Table 120.1-A and required to install occupant sensors to comply with Section 130.1(c)5, 6, and 7. Occupant sensor ventilation control devices used to reduce the rate of outdoor airflow when occupants are not present shall comply with the following:
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:
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.
EXCEPTION to Section 120.1(g)2E: When using any energy recovery device, recirculation from leakage, carryover, or transfer from the exhaust side of the energy recovery device is permitted. Recirculated Class 2 air shall not exceed 10% of the outdoor air intake flow.
EXCEPTION to Section 120.1(g)3B: When using any energy recovery device, recirculation from leakage, carryover, or transfer from the exhaust side of the energy recovery device is permitted. Recirculated Class 3 air shall not exceed 5% of the outdoor air intake flow.
HVAC Systems without mechanical cooling or mechanical heating shall meet the requirements of Section 120.2(f).
Occupancy Category
|
Total Outdoor Air Rate1 Rt
(cfm/ft2) |
Min Ventilation Air Rate for DCV
Ra (cfm/ft2) |
Air Class
|
Notes
| ||
Educational Facilities
|
||||||
Daycare (through age 4)
|
0.21
|
0.15
|
2
|
|||
Daycare sickroom
|
0.15
|
3
|
||||
Classrooms (ages 5-8)
|
0.38
|
0.15
|
1
|
|||
Classrooms (age 9 -18)
|
0.38
|
0.15
|
1
|
|||
Lecture/postsecondary classroom
|
0.38
|
0.15
|
1
|
F
| ||
Lecture hall (fixed seats)
|
-
|
0.15
|
1
|
F
| ||
Art classroom
|
0.15
|
2
|
||||
Science laboratories
|
0.15
|
2
|
||||
University/college laboratories
|
0.15
|
2
|
||||
Wood/metal shop
|
0.15
|
2
|
||||
Computer lab
|
0.15
|
1
|
||||
Media center
|
0.15
|
1
|
A
| |||
Music/theater/dance
|
1.07
|
0.15
|
1
|
F
| ||
Multiuse assembly
|
0.5
|
0.15
|
1
|
F
| ||
Food and Beverage Service
|
||||||
Restaurant dining rooms
|
0.5
|
0.15
|
2
|
|||
Cafeteria/fast-food dining
|
0.5
|
0.15
|
2
|
|||
Bars, cocktail lounges
|
0.5
|
0.2
|
2
|
|||
Kitchen (cooking)
|
0.15
|
2
|
||||
General
|
||||||
Break rooms
|
0.5
|
0.15
|
1
|
F
| ||
Coffee Stations
|
0.5
|
0.15
|
1
|
F
| ||
Conference/meeting
|
0.5
|
0.15
|
1
|
F
| ||
Corridors
|
0.15
|
1
|
F
| |||
Occupiable storage rooms for liquids or gels
|
0.15
|
2
|
B
| |||
Hotels, Motels, Resorts, Dormitories
|
||||||
Bedroom/living room
|
0.15
|
1
|
F
| |||
Barracks sleeping areas
|
0.15
|
1
|
F
| |||
Laundry rooms, central
|
0.15
|
2
|
||||
Laundry rooms within dwelling units
|
0.15
|
1
|
||||
Lobbies/pre-function
|
0.5
|
0.15
|
1
|
F
| ||
Multipurpose assembly
|
0.5
|
1
|
F
| |||
Office Buildings
|
||||||
Breakrooms
|
0.5
|
0.15
|
1
|
|||
Main entry lobbies
|
0.5
|
0.15
|
1
|
F
| ||
Occupiable storage rooms for dry materials
|
0.15
|
1
|
||||
Office space
|
0.15
|
1
|
F
| |||
Reception areas
|
0.15
|
1
|
F
| |||
Telephone/data entry
|
0.15
|
1
|
F
| |||
Miscellaneous Spaces
|
||||||
Bank vaults/safe deposit
|
0.15
|
2
|
F
| |||
Banks or bank lobbies
|
0.15
|
1
|
F
| |||
Computer (not printing)
|
0.15
|
1
|
F
| |||
Freezer and refrigerated spaces (<50oF)
|
-
|
2
|
E
| |||
General manufacturing (excludes heavy industrial and process using chemicals)
|
0.15
|
3
|
||||
Pharmacy (prep. Area)
|
0.15
|
2
|
||||
Photo studios
|
0.15
|
1
|
||||
Shipping/receiving
|
0.15
|
2
|
B
| |||
Sorting, packing, light assembly
|
0.15
|
2
|
||||
Telephone closets
|
0.15
|
1
|
||||
Transportation waiting
|
0.5
|
0.15
|
1
|
F
| ||
Warehouses
|
0.15
|
2
|
B
| |||
All others
|
0.15
|
2
|
||||
Public Assembly Spaces
|
||||||
Auditorium seating area
|
1.07
|
0.15
|
1
|
F
| ||
Places of religious worship
|
1.07
|
0.15
|
1
|
F
| ||
Courtrooms
|
0.19
|
0.15
|
1
|
F
| ||
Legislative chambers
|
0.19
|
0.15
|
1
|
F
| ||
Libraries (reading rooms and stack areas)
|
0.15
|
1
|
||||
Lobbies
|
0.5
|
0.15
|
1
|
F
| ||
Museums (children’s)
|
0.25
|
0.15
|
1
|
|||
Museums/galleries
|
0.25
|
0.15
|
1
|
F
| ||
Residential
|
||||||
Common corridors
|
0.15
|
1
|
F
| |||
Retail
|
||||||
Sales (except as below)
|
0.25
|
0.2
|
2
|
|||
Mall common areas
|
0.25
|
0.15
|
1
|
F
| ||
Barbershop
|
0.4
|
2
|
||||
Beauty and nail salons
|
0.4
|
2
|
||||
Pet shops (animal areas)
|
0.25
|
0.15
|
2
|
|||
Supermarket
|
0.25
|
0.2
|
1
|
F
| ||
Coin-operated laundries
|
0.3
|
2
|
||||
Sports and Entertainment
|
||||||
Gym, sports arena (play area)
|
0.5
|
0.15
|
2
|
E
| ||
Spectator areas |
0.5
|
0.15
|
1
|
F
| ||
Swimming (pool)
|
0.15
|
2
|
C
| |||
Swimming (deck)
|
0.5
|
0.15
|
2
|
C
| ||
Disco/dance floors
|
1.5
|
0.15
|
2
|
F
| ||
Health club/aerobics room
|
0.15
|
2
|
||||
Health club/weight rooms
|
0.15
|
2
|
||||
Bowling alley (seating)
|
1.07
|
0.15
|
1
|
|||
Gambling casinos
|
0.68
|
0.15
|
1
|
|||
Game arcades
|
0.68
|
0.15
|
1
|
|||
Stages, studios
|
0.5
|
0.15
|
1
|
D, F
| ||
General footnotes for Table 120.1-A:
1 Rt is determined as being the larger of the area method and the default per person method. The occupant density used in the default per person method is one half of the maximum occupant load assumed for egress purposes in the CBC. | ||||||
Specific Notes:
| ||||||
A – For high-school and college libraries, the values shown for “Public Assembly Spaces – Libraries” shall be used.
| ||||||
B – Rate may not be sufficient where stored materials include those having potentially harmful emissions.
| ||||||
C – Rate does not allow for humidity control. “Deck area” refers to the area surrounding the pool that is capable of being wetted during pool use or when the pool is occupied. Deck area that is not expected to be wetted shall be designated as an occupancy category.
| ||||||
D – Rate does not include special exhaust for stage effects such as dry ice vapors and smoke.
| ||||||
E – Where combustion equipment is intended to be used on the playing surface or in the space, additional dilution ventilation, source control, or both shall be provided.
| ||||||
F – Ventilation air for this occupancy category shall be permitted to be reduced to zero when the space is in occupied-standby mode.
| ||||||
Occupancy Category | Exhaust Rate, cfm/unit | Exhaust Rate, cfm/ft2 | Air Class | Notes |
Arenas | - | 0.50 | 1 | B |
Art classrooms | - | 0.70 | 2 | |
Auto repair rooms | - | 1.5 | 2 | A |
Barber shops | - | 0.50 | 2 | |
Beauty and nail salons | - | 0.60 | 2 | |
Cells with toilet | - | 1.00 | 2 | |
Copy, printing rooms | - | 0.50 | 2 | |
Darkrooms | - | 1.00 | 2 | |
Educational science laboratories | - | 1.00 | 2 | |
Janitor closets, trash rooms, recycling | - | 1.00 | 3 | |
Kitchenettes | - | 0.30 | 2 | |
Kitchens – commercial | - | 0.70 | 2 | |
Locker rooms for athletic or industrial facilities | - | 0.50 | 2 | |
All other locker rooms | - | 0.25 | 2 | |
Shower rooms | 20/50 | - | 2 | G,H |
Paint spray booths | - | - | 4 | F |
Parking garages | - | 0.75 | 2 | C |
Pet shops (animal areas) | - | 0.90 | 2 | |
Refrigerating machinery rooms | - | - | 3 | F |
Soiled laundry storage rooms | - | 1.00 | 3 | F |
Storage rooms, chemical | - | 1.50 | 4 | F |
Toilets – private | 25/50 | - | 2 | E |
Toilets – public | 50/70 | - | 2 | D |
Woodwork shop/classrooms | - | 0.50 | 2 | |
Notes: | ||||
A – Stands where engines are run shall have exhaust systems that directly connect to the engine exhaust and prevent escape of fumes. | ||||
B – Where combustion equipment is intended to be used on the playing surface, additional dilution ventilation, source control, or both shall be provided. | ||||
C – Exhaust shall not be required where two or more sides comprise walls that are at least 50% open to the outside. | ||||
D – Rate is per water closet, urinal, or both. Provide the higher rate where periods of heavy use are expected to occur. The lower rate shall be permitted to be used otherwise. | ||||
E – Rate is for a toilet room intended to be occupied by one person at a time. For continuous systems operation during hours of use, the lower rate shall be permitted to be used. Otherwise the higher rate shall be used. | ||||
F – See other applicable standards for exhaust rate. | ||||
G – For continuous system operation, the lower rate shall be permitted to be used. Otherwise the higher rate shall be used. | ||||
H – Rate is per showerhead |
Description | Air Class |
Diazo printing equipment discharge | 4 |
Commercial kitchen grease hoods | 4 |
Commercial kitchen hoods other than grease | 3 |
Laboratory hoods | 4a |
Hydraulic elevator machine room | 2 |
a. Air Class 4 unless determined otherwise by the Environmental Health and Safety professional responsible to the owner or to the owner’s designee. |
NOTE: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code. Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.8, and 25943, Public Resources Code.