Air intake openings shall comply with all of the following:
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. Louvers that protect air intake openings in structures located in hurricane-prone regions, as defined in the International Building Code, shall comply with AMCA 550. Outdoor air intake openings located in exterior walls shall meet the provisions for exterior wall opening protectives in accordance with the International Building Code.
OPENING SIZES IN LOUVERS, GRILLES AND SCREENS PROTECTING AIR INTAKE OPENINGS
|OUTDOOR OPENING TYPE||MINIMUM AND MAXIMUM |
OPENING SIZES IN LOUVERS,GRILLES AND SCREENSa
|Intake openings in residential occupancies||Not < 1/4 inch and not > 1/2 inch|
|Intake openings in other than residential occupancies||> 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 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. Outdoor air shall be supplied directly to each occupiable space from an air handling unit through a fully ducted path or ducted to within 12 inches (305 mm) of the return air opening of a fan-powered terminal unit used to transfer the outdoor air to the occupiable space. 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, including transfer fan-powered terminal units 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: Where occupancy density is known and documented in the plans, the outside air rate may be based on the design occupant density. Under no circumstance shall the occupancies used result in outside air less than one-half that resulting from application of Table 403.3.1.1 estimated maximum occupancy rates.
REQUIRED OUTDOOR VENTILATION AIR
|OCCUPANCY CLASSIFICATION||OCCUPANT DENSITY
#/1000 FT2 a
AIRFLOW RATE INBREATHING ZONE,
AIRFLOW RATE INBREATHING ZONE,
Ra, CFM/FT2 a
AIRFLOW RATECFM/FT2 a
|without plumbing fixtures||25||5||0.12||—|
|with plumbing fixturesg||25||5||0.12||1.0|
(see "Food and beverage service")
|Dry cleaners, laundries|
|Coin-operated dry cleaner||20||15||—||—|
|Commercial dry cleaner||30||30||—||—|
|Storage, pick up||30||7.5||0.12||—|
|Classrooms (ages 5-8)||25||10||0.12||—|
|Classrooms (age 9 plus)||35||10||0.12||—|
|Corridors (see "Public spaces")||—||—||—||—|
|Day care (through age 4)||25||10||0.18||—|
|Lecture hall (fixed seats)||150||7.5||0.06||—|
|Sports locker roomsg||—||—||—||0.5|
|Food and beverage service|
|Bars, cocktail lounges||100||7.5||0.18||—|
|Cafeteria, fast food||100||7.5||0.18||—|
|Hotels, motels, resorts and dormitories|
|Dormitory sleeping areas||20||5||0.06||—|
|Main entry lobbies||10||5||0.06||—|
|Private dwellings, single and multiple|
|Garages, common for multiple unitsb||—||—||—||0.75|
|Kitchensb||—||—||—||See Table 403.4.7|
|Living areasc||—||See Table 403.4.2||—||—|
|Toilet rooms and bathroomsg||—||—||—||See Table 403.4.7|
|Corridors serving other than Group R||—||—||0.06||—|
|Corridors serving Group R dwelling or
sleeping units with whole-house exhaustsystem
|Corridors serving Group R dwelling or
sleeping units with other than whole-houseexhaust system
|Elevator lobbies in parking garage||—||—||1.0||—|
|Places of religious worship||120||5||0.06||—|
|Shower room (per shower head)g||—||—||—||50/20f|
|Toilet rooms — publicg||—||—||—||50/70e|
|Retail stores, sales floors and
|Mall common areas||40||7.5||0.06||—|
|Shipping and receiving||2||10||0.12||—|
|Warehouses (see "Storage")||—||10||0.06||—|
|Automotive motor-fuel dispensing stationsb||—||—||—||1.5|
|Nail salons b, h||25||20||0.12||0.6|
|Pet shops (animal areas)b||10||7.5||0.18||0.9|
|Sports and amusement|
|Bowling alleys (seating areas)||40||10||0.12||—|
|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|
|Swimming pools (pool and deck area)||—||—||0.48||—|
|Janitor closets, trash rooms, recycling rooms||1.0|
|Repair garages, enclosed parking garagesb,d||—||—||—||0.75|
|Storage rooms, chemical||—||—||—||1.5|
|Auditoriums (see "Education")||—||—||—||—|
|Bank vaults/safe deposit||5||5||0.06||—|
|Computer (without printing)||4||5||0.06||—|
|Copy, printing rooms||4||5||0.06||0.5|
|Freezer and refrigerated spaces (<50°F)||0||10||0||0|
|Pharmacy (prep. area)||10||5||0.18||—|
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.
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 or return||0.8|
|Makeup air drawn in near to the exhaust 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.
The zone outdoor airflow rate (Voz), shall be determined in accordance with Equation 4-2.
The uncorrected outdoor air intake flow (Vot) shall be determined in accordance with Equation 4-5.
The occupant diversity ratio (D) shall be determined in accordance with Equation 4-6 to account for variations in population within the ventilation zones served by the system.
Ps = System population: The total population in the area served by the system.
Exception: Alternative methods to account for occupant diversity shall be permitted, provided the resulting Vou value is no less than that determined using Equation 4-5.
Note: Design system population is always equal to or less than the sum of design zone population for all zones in the area served by the system because all zones may or may not be simultaneously occupied at design population.
The system ventilation efficiency (Ev) shall be determined in accordance with Section 403.3.1.1.2.3.3 for the Simplified Procedure or Appendix A of ASHRAE 62.1 for the Alternative Procedure.
Note: These procedures also establish zone minimum primary airflow rates for VAV systems.
System ventilation efficiency (Ev) shall be determined in accordance with Equation 4-6a or 4-6b.
For each zone, the minimum primary airflow (Vpz-min) shall be determined in accordance with Equation 4-7.
The design outdoor air intake flow rate (Vot) shall be determined in accordance with Equation 4-8.
The sleeping unit whole-house mechanical ventilation minimum outdoor airflow rate shall be determined in accordance with the breathing zone ventilation rates. Minimum outdoor airflow rate shall be determined in accordance with the breathing zone ventilation rate requirements of Section 403.3.1.1.1.2 using Equation 4-2. The dwelling unit whole-house mechanical ventilation minimum outdoor airflow rate shall be determined in accordance with Equation 4-10 or Table 403.4.2.
WHOLE-HOUSE MECHANICAL VENTILATION AIRFLOW RATE (CONTINUOUSLY OPERATING SYSTEMS)
|FLOOR AREA (ft2)||BEDROOMSa|
|500 - 1000||30||35||40||50||55|
|1001 - 1500||30||40||45||55||60|
|1501 - 2000||35||45||50||60||65|
|2001 - 2500||40||50||55||65||70|
|2501 - 3000||45||55||60||70||75|
|3001 - 3500||50||60||65||75||80|
|3501 - 4000||55||65||70||80||85|
|4001 - 4500||60||70||75||85||90|
|4501 - 5000||65||75||80||90||95|
For SI: 1 square foot = 0.092903 m2 , 1 cubic foot per minute = 0.03 m3/min.
The minimum whole-house ventilation rate from Section 403.4.2 shall be adjusted by the system coefficient in Table 403.4.3 based on the system type not meeting the definition of a balanced whole-house ventilation system and/or not meeting the definition of a distributed whole-house ventilation system.
SYSTEM COEFFICIENT (Csystem)
|SYSTEM TYPE||DISTRIBUTED||NOT DISTRIBUTED|
Whole-house ventilation supply and exhaust fans specified in this section shall have a minimum efficacy as prescribed in the Washington State Energy Code. The fans shall be rated for sound at a maximum of 1.0 sone at design airflow and static pressure conditions. Design and installation of the system or equipment shall be carried out in accordance with manufacturer's installation instructions.
Exhaust fans required shall be ducted directly to the outside in accordance with Section 501.3. Exhaust air outlets shall be designed to limit the pressure difference to the outside to limiting the outlet free area maximum velocity to 500 feet per minute (152 m/min) and equipped with backdraft dampers or motorized dampers in accordance with the Washington State Energy Code. Exhaust fans shall be tested and rated in accordance with HVI 915, HVI 916, and HVI 920. Exhaust fans required in this section may be used to provide local ventilation. Exhaust fans that are designed for intermittent exhaust airflow rates higher than the continuous exhaust airflow rates in Table 403.4.3 shall be provided with occupancy sensors or humidity sensors to automatically override the fan to the high-speed airflow rate. The exhaust fans shall be tested and the testing results shall be submitted and posted in accordance with Section 403.4.6.7.
Exception: Central exhaust fans serving multiple residential units do not need to comply with the HVI testing requirements.
Supply fans used in meeting the requirements of this section shall supply outdoor air from intake openings in accordance with Sections 401.4 and 401.5. Intake air openings shall be designed to limit the pressure difference to the outside to limiting the inlet free area maximum velocity to 500 feet per minute (152 m/min) and when designed for intermittent off operation shall be equipped with motorized dampers in accordance with the Washington State Energy Code. Supply fans shall be tested and rated in accordance with HVI 915, HVI 916, and HVI 920. Where outdoor air is provided to each habitable dwelling unit or sleeping unit by supply fan systems the outdoor air shall be filtered. The filter shall be provided with access for regular maintenance and replacement. The filter shall have a Minimum Efficiency Rating Value (MERV) of at least 8.
Exception: Central supply fans serving multiple residential units do not need to comply with the HVI testing requirements
Exception: Air handler fans shall be permitted that have multi-speed or variable speed supply airflow control capability with a low-speed operation not greater than 25 percent of the rated supply airflow capacity during ventilation-only operation. Outdoor air intake openings must meet the provisions of Sections 401.4 and 401.5 and must include a motorized damper that is activated by the whole-house ventilation system controller. Intake air openings shall be designed to limit the pressure difference to the outside to limiting the inlet free area maximum velocity to 500 ft per min (152 m/min). The motorized damper must be controlled to maintain the outdoor airflow intake airflow within 10 percent of the whole-house mechanical exhaust airflow rate. The supply air handler shall provide supply air to each habitable space in the residential unit. The whole-house ventilation system shall include exhaust fans in accordance with Section 403.4.6.2 to meet the pressure equalization requirements of Section 501.4. The flow rate for the outdoor air intake must be tested and verified at the minimum ventilation fan speed and the maximum heating or cooling fan speed. The results of the test shall be submitted and posted in accordance with Section 403.4.6.6
Whole-house mechanical ventilation systems shall be provided with advanced controls that are configured to operate the system with intermittent off operation and shall operate for a least two hours in each four-hour segment. The whole house ventilation airflow rate determined in accordance with Section 403.4.2 as corrected by Section 403.4.3 shall be multiplied by the factor determined in accordance with Table 403.4.6.5.
Bathrooms, toilet rooms and kitchens shall include a local exhaust system. Such local exhaust systems shall have the capacity to exhaust the minimum airflow rate in accordance with Table 403.4.7 and Table 403.3.1.1, including notes. Fans required by this section shall be provided with controls that enable manual override or automatic occupancy sensor, humidity sensor or pollutant sensor controls. An "on/off" switch shall meet this requirement for manual controls. Manual fan controls shall be provided with ready access in the room served by the fan.
Exhaust fans shall meet the following criteria.
PRESCRIPTIVE EXHAUST DUCT SIZING
|Fan Tested cfm at |
0.25 inches w.g.
|Minimum Flex Diameter||Maximum Length |
|Minimum Smooth |
|Maximum Length |
|50||4 inches||25||4 inches||70||3|
|50||5 inches||90||5 inches||100||3|
|50||6 inches||No Limit||6 inches||No Limit||3|
|80||4 inchesb||Not Allowed||4 inches||20||3|
|80||5 inches||15||5 inches||100||3|
|80||6 inches||90||6 inches||No Limit||3|
|100||5 inchesb||Not Allowed||5 inches||50||3|
|100||6 inches||45||6 inches||No Limit||3|
|125||6 inches||15||6 inches||No Limit||3|
|125||7 inches||70||7 inches||No Limit||3|
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm.
Mechanical ventilation systems for enclosed parking garages shall operate continuously or shall be automatically operated by means of carbon monoxide detectors applied in conjunction with nitrogen dioxide detectors. Such detectors shall be listed in accordance with UL 2075 and installed in accordance with their listing and the manufacturers' instructions. Automatic operation shall cycle the ventilation system between the following two modes of operation:
Mechanical ventilation for health care facilities licensed by Washington State shall be designed and installed in accordance with this code and the following provisions of the Washington Administrative Code (WAC):
Mechanical ventilation for unlicensed ambulatory care facilities shall be designed and installed in accordance with this code and ASHRAE 170.