Air intake openings shall comply with all of the following:
- Intake openings shall be located a minimum of 10 feet (3048 mm) from lot lines or buildings on the same lot. Where openings front on a street or public way, the distance shall be measured to the centerline of the street or public way.
- Mechanical and gravity outdoor air intake openings shall be located not less than 10 feet (3048 mm) horizontally from any hazardous or noxious contaminant source, such as vents, streets, alleys, parking lots and loading docks, except as specified in Item 3 or Section 501.2.1.
- Intake openings shall be located not less than 3 feet (914 mm) below contaminant sources where such sources are located within 10 feet (3048 mm) of the opening.
- Intake openings on structures in flood hazard areas shall be at or above the design flood level.
Air intake openings that terminate outdoors shall be protected with corrosion-resistant screens, louvers or grilles. Openings in louvers, grilles and screens shall be sized in accordance with Table 401.5, and shall be protected against local weather conditions. Outdoor air intake openings located in exterior walls shall meet the provisions for exterior wall opening protectives in accordance with the building code.
OPENING SIZES IN LOUVERS, GRILLES AND SCREENS PROTECTING AIR INTAKE OPENINGS
|OUTDOOR OPENING TYPE||MINIMUM AND MAXIMUM OPENING|
SIZES IN LOUVERS, GRILLES ANDSCREENS MEASURED IN ANY
|Intake openings in residential |
|Not < 1/4 inch and not > 1/2 inch|
|Intake openings in other than |
|> 1/4 inch and not > 1 inch|
For SI: 1 inch = 25.4 mm.
Where rooms and spaces without openings to the outdoors are ventilated through an adjoining room, the opening to the adjoining rooms shall be unobstructed and shall have an area not less than 8 percent of the floor area of the interior room or space, but not less than 25 square feet (2.3 m2). The minimum openable area to the outdoors shall be based on the total floor area being ventilated.
Exception: Exterior openings required for ventilation shall be permitted to open into a thermally isolated sunroom addition or patio cover, provided that the openable area between the sunroom addition or patio cover and the interior room has an area of not less than 8 percent of the floor area of the interior room or space, but not less than 20 square feet (1.86 m2). The minimum openable area to the outdoors shall be based on the total floor area being ventilated.
The minimum outdoor airflow rate shall be determined in accordance with Section 403.3. Ventilation supply systems shall be designed to deliver the required rate of outdoor airflow to the breathing zone within each occupiable space.
Exception: The registered design professional may use ASHRAE 62.1 or ASHRAE 62.2, as applicable, as an alternative engineered ventilation system design provided that the registered design professional demonstrates compliance with all applicable sections of the ASHRAE standard.
The outdoor air required by Section 403.3 shall not be recirculated. Air in excess of that required by Section 403.3 shall not be prohibited from being recirculated as a component of supply air to building spaces, except that:
- Ventilation air shall not be recirculated from one dwelling to another or to dissimilar occupancies.
- Supply air to a swimming pool and associated deck areas shall not be recirculated unless such air is dehumidified to maintain the relative humidity of the area at 60 percent or less. Air from this area shall not be recirculated to other spaces where more than 10 percent of the resulting supply airstream consists of air recirculated from these spaces.
- Where mechanical exhaust is required by Note b in Table 403.3, recirculation of air from such spaces shall be prohibited. All air supplied to such spaces shall be exhausted, including any air in excess of that required by Table 403.3.
- Where mechanical exhaust is required by Note g in Table 403.3, mechanical exhaust is required and recirculation is prohibited where more than 10 percent of the resulting supply airstream consists of air recirculated from these spaces.
Ventilation systems shall be designed to have the capacity to supply the minimum outdoor airflow rate determined in accordance with this section. The occupant load utilized for design of the ventilation system shall not be less than the number determined from the estimated maximum occupant load rate indicated in Table 403.3. Ventilation rates for occupancies not represented in Table 403.3 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 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 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 where approved statistical data document the accuracy of an alternate anticipated occupant density.
MINIMUM VENTILATION RATES
|OCCUPANCY CLASSIFICATION||PEOPLE OUTDOOR|
AIRFLOW RATE INBREATHING ZONE, Rp
AIRFLOW RATE IN
BREATHING ZONE, RaCFM/FT2 a
DENSITY #/1000 FT2 a,i
RATE CFM/FT2 a
|without plumbing fixtures||5||0.12||25||—|
|with plumbing fixturesg||5||0.12||25||1.0|
|Dining halls |
(see food and beverage service)
|Dry cleaners, laundries|
|Coin-operated dry cleaner||15||—||20||—|
|Commercial dry cleaner||30||—||30||—|
|Storage, pick up||7.5||0.12||30||—|
|Corridors (see public spaces)||—||—||—||—|
|Sports locker roomsg||—||—||—||0.5|
|Day care (through age 4)||10||0.18||25||—|
|Classrooms (ages 5-8)||10||0.12||25||—|
|Classrooms (age 9 plus)||10||0.12||35||—|
|Lecture hall (fixed seats)||7.5||0.06||150||—|
|Food and beverage service|
|Bars, cocktail lounges||7.5||0.18||100||—|
|Cafeteria, fast food||7.5||0.18||100||—|
|Hotels, motels, resorts and dormitories|
|Dormitory sleeping areas||5||0.06||20||—|
|Main entry lobbies||5||0.06||10||—|
|Private dwellings, single and multiple|
|Garages, common for multiple unitsb||—||—||—||0.75|
|Garages, separate for each dwellingb||—||—||—||100 cfm per car|
|Living areasc||0.35 ACH but not less than 15 cfm/person||—||Based upon number of |
bedrooms. Firstbedroom, 2; each
additional bedroom, 1
|Toilet rooms and bathroomsg||—||—||—||20/50f|
|Shower room (per shower head)g||—||—||—||50/20f|
|Toilet rooms – publicg||—||—||—||50/70e|
|Places of religious worship||5||0.06||120||—|
|Retail stores, sales floors and |
|Sales (except as below)||7.5||0.12||15||—|
|Mall common areas||7.5||0.06||40||—|
|Shipping and receiving||—||0.12||—||—|
|Warehouses (see storage)||—||—||—||—|
|Automotive motor-fuel dispensing stationsb||—||—||—||1.5|
|Beauty and nail salonsb, h||20||0.12||25||0.6|
|Pet shops (animal areas)b||7.5||0.18||10||0.9|
|Sports and amusement|
|Bowling alleys (seating areas)||10||0.12||40||—|
|Ice arenas without combustion engines||—||0.30||—||0.5|
|Gym, stadium, arena (play area)||—||0.30||—||—|
|Swimming pools (pool and deck area)||—||0.48||—||—|
|Health club/aerobics room||20||0.06||40||—|
|Health club/weight room||20||0.06||10||—|
|Repair garages, enclosed parking garagesb,d||—||—||—||0.75|
|Auditoriums (see education)||—||—||—||—|
|Bank vaults/safe deposit||5||0.06||5||—|
|Copy, printing rooms||5||0.06||4||0.5|
|Pharmacy (prep. area)||5||0.18||10||—|
|Computer (without printing)||5||0.06||4||—|
For SI: 1 cubic foot per minute = 0.0004719 m3/s, 1 ton = 908 kg, 1 cubic foot per minute per square foot = 0.00508m3/(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 (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 periods of heavy use are expected to occur, such as toilets in theaters, schools and sports facilities. The lower rate shall be permitted where periods of heavy use are not expected.
- 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 where the exhaust system is designed to operate continuously during normal hours of use.
- Mechanical exhaust is required and recirculation 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 (see Section 403.2.1, Items 2 and 4).
- For nail salons, the required exhaust shall include ventilation tables or other systems that capture the contaminants and odors at their source and are capable of exhausting a minimum of 50 cfm per station.
- The occupant load shall not be greater than that determined by Section 1004 of the building code.
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.
|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.|
|Ra||=||Area outdoor air rate: the outdoor airflow rate required per unit area from Table 403.3.|
The zone air distribution effectiveness (Ez) shall be determined using Table 403.3.1.2.
ZONE AIR DISTRIBUTION EFFECTIVENESSa,b,c,d,e
|Air Distribution Configuration||Ez|
|Ceiling or floor supply of cool air||1.0f|
|Ceiling or floor supply of warm air and floor return||1.0|
|Ceiling supply of warm air and ceiling return||0.8g|
|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
|Makeup air drawn in near to the exhaust and/or return |
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.
- “Makeup air” is air supplied or transferred to a zone to replace air removed from the zone by exhaust or return systems.
- Zone air distribution effectiveness of 1.2 shall be permitted for systems with a floor supply of cool air and ceiling return, provided that low-velocity 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 foot-per-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.
|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 403.3.2.3.2 or Appendix A of ASHRAE 62.1.
SYSTEM VENTILATION EFFICIENCYa,b
- 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.
|D||=||Occupant diversity: the ratio of the system population to the sum of the zone populations, determined in accordance with Equation 4-7.|
|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.
Mechanical ventilation for ambulatory care facilities and Group I-2 occupancies shall be designed and installed in accordance with this code and ASHRAE 170.