Ventilation systems shall be designed to have the capacity to supply the minimum outdoor airflow rate, determined in accordance with this section. In each occupiable space, the ventilation system shall be designed to deliver the required rate of outdoor airflow to the breathing zone. The occupant load utilized for design of the ventilation system shall be not less than the number determined from the estimated maximum occupant load rate indicated in Table 403.3.1.1. Ventilation rates for occupancies not represented in Table 403.3.1.1 shall be those for a listed occupancy classification that is most similar in terms of occupant density, activities and building construction; or shall be determined by an approved engineering analysis. The ventilation system shall be designed to supply the required rate of ventilation air continuously during the period the building is occupied, except as otherwise stated in other provisions of the code.
With the exception of smoking lounges, the ventilation rates in Table 403.3.1.1 are based on the absence of smoking in occupiable spaces. Where smoking is anticipated in a space other than a smoking lounge, the ventilation system serving the space shall be designed to provide ventilation over and above that required by Table 403.3.1.1 in accordance with accepted engineering practice.
Exception: The occupant load is not required to be determined based on the estimated maximum occupant load rate indicated in Table 403.3.1.1 where approved statistical data document the accuracy of an alternate anticipated occupant density.
MINIMUM VENTILATION RATES
| OCCUPANCY CLASSIFICATION | OCCUPANT DENSITY #/1000 FT2 a | PEOPLE OUTDOOR AIRFLOW RATE IN BREATHING ZONE, Rp CFM/PERSON | AREA OUTDOOR AIRFLOW RATE IN BREATHING ZONE, Ra CFM/FT2 a | EXHAUST AIRFLOW RATE CFM/FT2 a | |
| Correctional facilities | |||||
| Booking/waiting | 50 | 7.5 | 0.06 | — | |
| Cells | |||||
| without plumbing fixtures | 25 | 5 | 0.12 | — | |
| with plumbing fixturesg | 25 | 5 | 0.12 | 1.0 | |
| Day room | 30 | 5 | 0.06 | — | |
| Dining halls | |||||
| (see food and beverage service) | — | — | — | — | |
| Guard stations | 15 | 5 | 0.06 | — | |
| Dry cleaners, laundries | |||||
| Coin-operated dry cleaner | 20 | 15 | — | — | |
| Coin-operated laundries | 20 | 7.5 | 0.06 | — | |
| Commercial dry cleaner | 30 | 30 | — | — | |
| Commercial laundry | 10 | 25 | — | — | |
| Storage, pick up | 30 | 7.5 | 0.12 | — | |
| Education | |||||
| Art classroomg | 20 | 10 | 0.18 | 0.7 | |
| Auditoriums | 150 | 5 | 0.06 | — | |
| Classrooms (ages 5-8) | 25 | 10 | 0.12 | — | |
| Classrooms (age 9 plus) | 35 | 10 | 0.12 | — | |
| Computer lab | 25 | 10 | 0.12 | — | |
| Corridors (see public spaces) | — | — | — | — | |
| Day care (through age 4) | 25 | 10 | 0.18 | — | |
| Lecture classroom | 65 | 7.5 | 0.06 | — | |
| Lecture hall (fixed seats) | 150 | 7.5 | 0.06 | — | |
| Locker/dressing roomsg | — | — | — | 0.25 | |
| Media center | 25 | 10 | 0.12 | — | |
| Multiuse assembly | 100 | 7.5 | 0.06 | — | |
| Music/theater/dance | 35 | 10 | 0.06 | — | |
| Science laboratoriesg | 25 | 10 | 0.18 | 1.0 | |
| Smoking loungesb | 70 | 60 | — | — | |
| Sports locker roomsg | — | — | — | 0.5 | |
| Wood/metal shopsg | 20 | 10 | 0.18 | 0.5 | |
| Food and beverage service | |||||
| Bars, cocktail lounges | 100 | 7.5 | 0.18 | — | |
| Cafeteria, fast food | 100 | 7.5 | 0.18 | — | |
| Dining rooms | 70 | 7.5 | 0.18 | — | |
| Kitchens (cooking)b | — | — | — | 0.7 | |
| Hotels, motels, resorts and dormitories | |||||
| Bathrooms/toilet—privateg | — | — | — | 25/50f | |
| Bedroom/living room | 10 | 5 | 0.06 | — | |
| Conference/meeting | 50 | 5 | 0.06 | — | |
| Dormitory sleeping areas | 20 | 5 | 0.06 | — | |
| Gambling casinos | 120 | 7.5 | 0.18 | — | |
| Lobbies/prefunction | 30 | 7.5 | 0.06 | — | |
| Multipurpose assembly | 120 | 5 | 0.06 | — | |
| Offices | |||||
| Conference rooms | 50 | 5 | 0.06 | — | |
| Main entry lobbies | 10 | 5 | 0.06 | — | |
| Office spaces | 5 | 5 | 0.06 | — | |
| Reception areas | 30 | 5 | 0.06 | — | |
| Telephone/data entry | 60 | 5 | 0.06 | — | |
| Private dwellings, single and multiple | |||||
| Garages, common for multiple unitsb | — | — | — | 0.75 | |
| Kitchensb | — | — | — | 25/100f | |
| Living areasc | Based upon number of bedrooms. First bedroom, 2; each additional bedroom, 1 | 0.35 ACH but not less than 15 cfm/person | — | — | |
| Toilet rooms and bathroomsg | — | — | — | 20/50f | |
| Public spaces | |||||
| Corridors | — | — | 0.06 | — | |
| Courtrooms | 70 | 5 | 0.06 | — | |
| Elevator car | — | — | — | 1.0 | |
| Legislative chambers | 50 | 5 | 0.06 | — | |
| Libraries | 10 | 5 | 0.12 | — | |
| Museums (children's) | 40 | 7.5 | 0.12 | — | |
| Museums/galleries | 40 | 7.5 | 0.06 | — | |
| Places of religious worship | 120 | 5 | 0.06 | — | |
| Shower room (per shower head)g | — | — | — | 50/20f | |
| Smoking loungesb | 70 | 60 | — | — | |
| Toilet rooms — publicg | — | — | — | 50/70e | |
| Retail stores, sales floors and showroom floors | |||||
| Dressing rooms | — | — | — | 0.25 | |
| Mall common areas | 40 | 7.5 | 0.06 | — | |
| Sales | 15 | 7.5 | 0.12 | — | |
| Shipping and receiving | — | — | 0.12 | — | |
| Smoking loungesb | 70 | 60 | — | — | |
| Storage rooms | — | — | 0.12 | — | |
| Warehouses (see storage) | — | — | — | — | |
| Specialty shops | |||||
| Automotive motor-fuel dispensing stationsb | — | — | — | 1.5 | |
| Barber | 25 | 7.5 | 0.06 | 0.5 | |
| Beauty salonsb | 25 | 20 | 0.12 | 0.6 | |
| Nail salons b, h | 25 | 20 | 0.12 | 0.6 | |
| Embalming roomb | — | — | — | 2.0 | |
| Pet shops (animal areas)b | 10 | 7.5 | 0.18 | 0.9 | |
| Supermarkets | 8 | 7.5 | 0.06 | — | |
| Sports and amusement | |||||
| Bowling alleys (seating areas) | 40 | 10 | 0.12 | — | |
| Disco/dance floors | 100 | 20 | 0.06 | — | |
| Game arcades | 20 | 7.5 | 0.18 | — | |
| Gym, stadium, arena (play area) | — | — | 0.30 | — | |
| Health club/aerobics room | 40 | 20 | 0.06 | — | |
| Health club/weight room | 10 | 20 | 0.06 | — | |
| Ice arenas without combustion engines | — | — | 0.30 | 0.5 | |
| Spectator areas | 150 | 7.5 | 0.06 | — | |
| Swimming pools (pool and deck area) | — | — | 0.48 | — | |
| Storage | |||||
| Repair garages, enclosed parking garagesb,d | — | — | — | 0.75 | |
| Warehouses | — | — | 0.06 | — | |
| Theaters | |||||
| Auditoriums (see education) | — | — | — | — | |
| Lobbies | 150 | 5 | 0.06 | — | |
| Stages, studios | 70 | 10 | 0.06 | — | |
| Ticket booths | 60 | 5 | 0.06 | — | |
| Transportation | |||||
| Platforms | 100 | 7.5 | 0.06 | — | |
| Transportation waiting | 100 | 7.5 | 0.06 | — | |
| Workrooms | |||||
| Bank vaults/safe deposit | 5 | 5 | 0.06 | — | |
| Computer (without printing) | 4 | 5 | 0.06 | — | |
| Copy, printing rooms | 4 | 5 | 0.06 | 0.5 | |
| Darkrooms | — | — | — | 1.0 | |
| Meat processingc | 10 | 15 | — | — | |
| Pharmacy (prep. area) | 10 | 5 | 0.18 | — | |
| Photo studios | 10 | 5 | 0.12 | — |
For SI: 1 cubic foot per minute = 0.0004719 m3/s, 1 ton = 908 kg, 1 cubic foot per minute per square foot = 0.00508 m3/(s • m2), °C = [(°F) -32]/1.8, 1 square foot = 0.0929 m2.
- Based upon net occupiable floor area.
- Mechanical exhaust required and the recirculation of air from such spaces is prohibited. Recirculation of air that is contained completely within such spaces shall not be prohibited (see Section 403.2.1, Item 3).
- Spaces unheated or maintained below 50°F are not covered by these requirements unless the occupancy is continuous.
- Ventilation systems in enclosed parking garages shall comply with Section 404.
- Rates are per water closet or urinal. The higher rate shall be provided where the exhaust system is designed to operate intermittently. The lower rate shall be permitted only where the exhaust system is designed to operate continuously while occupied.
- Rates are per room unless otherwise indicated. The higher rate shall be provided where the exhaust system is designed to operate intermittently. The lower rate shall be permitted only where the exhaust system is designed to operate continuously while occupied.
- Mechanical exhaust is required and recirculation from such spaces is prohibited except that recirculation shall be permitted where the resulting supply airstream consists of not more than 10 percent air recirculated from these spaces. Recirculation of air that is contained completely within such spaces shall not be prohibited (see Section 403.2.1, Items 2 and 4).
- For nail salons, each manicure and pedicure station shall be provided with a source capture system capable of exhausting not less than 50 cfm per station. Exhaust inlets shall be located in accordance with Section 502.20. Where one or more required source capture systems operate continuously during occupancy, the exhaust rate from such systems shall be permitted to be applied to the exhaust flow rate required by Table 403.3.1.1 for the nail salon.
The outdoor airflow rate required in the breathing zone (Vbz) of the occupiable space or spaces in a zone shall be determined in accordance with Equation 4-1.
where:
Az = Zone floor area: the net occupiable floor area of the space or spaces in the zone.
Pz = Zone population: the number of people in the space or spaces in the zone.
Rp = People outdoor air rate: the outdoor airflow rate required per person from Table 403.3.1.1.
Ra = Area outdoor air rate: the outdoor airflow rate required per unit area from Table 403.3.1.1.
The zone air distribution effectiveness (Ez) shall be determined using Table 403.3.1.1.1.2.
ZONE AIR DISTRIBUTION EFFECTIVENESSa,b,c,d
| AIR DISTRIBUTION CONFIGURATION | Ez |
| Ceiling or floor supply of cool air | 1.0e |
| Ceiling or floor supply of warm air and floor return | 1.0 |
| Ceiling supply of warm air and ceiling return | 0.8f |
| Floor supply of warm air and ceiling return | 0.7 |
| Makeup air drawn in on the opposite side of the room from the exhaust and/or return | 0.8 |
| Makeup air drawn in near to the exhaust and/or return location | 0.5 |
For SI: 1 foot = 304.8 mm, 1 foot per minute = 0.00506 m/s, °C = [(°F) — 32]/1.8.
- "Cool air" is air cooler than space temperature.
- "Warm air" is air warmer than space temperature.
- "Ceiling" includes any point above the breathing zone.
- "Floor" includes any point below the breathing zone.
- Zone air distribution effectiveness of 1.2 shall be permitted for systems with a floor supply of cool air and ceiling return, provided that lowvelocity displacement ventilation achieves unidirectional flow and thermal stratification.
- Zone air distribution effectiveness of 1.0 shall be permitted for systems with a ceiling supply of warm air, provided that supply air temperature is less than 15°F above space temperature and provided that the 150-footper-minute supply air jet reaches to within 41/2 feet of floor level.
The zone outdoor airflow rate (Voz), shall be determined in accordance with Equation 4-2.
Where one air handler supplies a mixture of outdoor air and recirculated return air to only one zone, the system outdoor air intake flow rate (Vot) shall be determined in accordance with Equation 4-3.
Where one air handler supplies only outdoor air to one or more zones, the system outdoor air intake flow rate (Vot) shall be determined using Equation 4-4.
The primary outdoor air fraction (Zp) shall be determined for each zone in accordance with Equation 4-5.
where:
Vpz = Primary airflow: The airflow rate supplied to the zone from the air-handling unit at which the outdoor air intake is located. It includes outdoor intake air and recirculated air from that air-handling unit but does not include air transferred or air recirculated to the zone by other means. For design purposes, Vpz shall be the zone design primary airflow rate, except for zones with variable air volume supply and Vpz shall be the lowest expected primary airflow rate to the zone when it is fully occupied.
The system ventilation efficiency (Ev) shall be determined using Table 403.3.1.1.2.3.2 or Appendix A of ASHRAE 62.1.
SYSTEM VENTILATION EFFICIENCYa,b
| Max (Zp) | Ev |
| ≤ 0.15 | 1 |
| ≤ 0.25 | 0.9 |
| ≤ 0.35 | 0.8 |
| ≤ 0.45 | 0.7 |
| ≤ 0.55 | 0.6 |
| ≤ 0.65 | 0.5 |
| ≤ 0.75 | 0.4 |
| > 0.75 | 0.3 |
- Max (Zp) is the largest value of Zp calculated using Equation 4-5 among all the zones served by the system.
- Interpolating between table values shall be permitted.
The uncorrected outdoor air intake flow rate (Vou) shall be determined in accordance with Equation 4-6.
where:
D = Occupant diversity: the ratio of the system population to the sum of the zone populations, determined in accordance with Equation 4-7.
where:
Ps = System population: The total number of occupants in the area served by the system. For design purposes, Ps shall be the maximum number of occupants expected to be concurrently in all zones served by the system.
The outdoor air intake flow rate (Vot) shall be determined in accordance with Equation 4-8.
