WAC 51-52-0403   Section 403 -- Mechanical ventilation.  


403.2 Outdoor air required. The minimum ventilation rate of outdoor air shall be determined in accordance with Section 403.3.


EXCEPTIONS: 1. Where the registered design professional demonstrates that an engineered ventilation system design will prevent the maximum concentration of contaminants from exceeding that obtainable by the rate of outdoor air ventilation determined in accordance with Section 403.3, the minimum required rate of outdoor air shall be reduced in accordance with such engineered system design.
2. Alternate systems designed in accordance with ASHRAE Standard 62.1.2004 Section 6.2, Ventilation Rate Procedure, shall be permitted.

403.2.1 Recirculation of air. The 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:

     1. Ventilation air shall not be recirculated from one dwelling to another or to dissimilar occupancies.

     2. 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 10 percent or more of the resulting supply airstream consists of air recirculated from these spaces.

     3. 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.

     (Item 4 is not adopted.)


403.3 Ventilation rate. Ventilation systems shall be designed to have the capacity to supply the minimum outdoor airflow rate determined in accordance with Table 403.3 based on the occupancy of the space and the occupant load or other parameter as stated therein. 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 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.


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 estimated maximum occupancy rates.

Table 403.3

     Required Outdoor Ventilation Air
Occupancy Classification Estimated Maximum Occupant Load, Persons per 1,000 Square Feeta Outdoor Air

     (Cubic feet per minute (cfm) per person) Unless Notede
Correctional facilities    
Cells    
  without plumbing fixtures 20 20
  with plumbing fixturesg 20 20
Dining halls 100 15
  Guard stations 40 15
Dry cleaners, laundries    
Coin-operated dry cleaner 20 15
Coin-operated laundries 20 15
Commercial dry cleaner 30 30
Commercial laundry 10 25
  Storage, pick up 30 35
Education    
Auditoriums 150 15
Classrooms 50 15
Corridors -- 0.10 cfm/ft2
Laboratories 30 20
Libraries 20 15
Locker rooms -- 0.50 cfm/ft2
Music rooms 50 15
Smoking loungesb,g 70 60
  Training shops 30 20
Food and beverage service    
Bars, cocktail lounges 100 30
Cafeteria, fast food 100 20
Dining rooms 70 20
  Kitchens (cooking)f,g 20 15
Hospitals, nursing and convalescent homes    
Autopsy roomsb -- 0.50 cfm/ft2
Medical procedure rooms 20 15
Operating rooms 20 30
Patient rooms 10 25
Physical therapy 20 15
  Recovery and ICU 20 15
Hotels, motels, resorts and dormitories    
Assembly rooms 120 15
Bathroomsg -- 35
Bedrooms -- 30 cfm per room
Conference rooms 50 20
Dormitory sleeping areas 20 15
Gambling casinos 120 30
Living rooms -- 30 cfm per room
  Lobbies 30 15
Offices    
Conference rooms 50 20
Office spaces 7 20
Reception areas 60 15
  Telecommunication centers and data entry 60 20
Private dwellings, single and multiple    
Garages, common for multiple unitsb -- 1.5 cfm/ft2
Garages, separate for each dwelling -- 100 cfm per car
Kitchensg -- 100 cfm intermittent or 25 cfm continuous
Living areasc Based upon number of bedrooms. First bedroom: 2; each additional: 1 0.35 air changes per houra or 15 cfm per person, whichever is greater
  Toilet rooms and bathroomsg -- Mechanical exhaust capacity of 50 cfm intermittent or 20 cfm continuous
Public spaces    
Corridors and utilities -- 0.05 cfm/ft2
Elevator carg -- 1.00 cfm/ft2
Locker rooms   0.5 cfm/ft2
Shower rooms (per shower head)g   50 cfm intermittent or 20 cfm continuous
Smoking loungesb 70 60
  Toilet roomsg   75 cfm per water closet or urinal
Retail stores, sales floors and showroom floors    
Basement and street -- 0.30 cfm/ft2
Dressing rooms -- 0.20 cfm/ft2
Malls and arcades -- 0.20 cfm/ft2
Shipping and receiving -- 0.15 cfm/ft2
Smoking loungesb 70 60
Storage rooms -- 0.15 cfm/ft2
Upper floors -- 0.20 cfm/ft2
  Warehouses -- 0.05 cfm/ft2
Specialty shops    
Automotive motor-fuel-dispensing stations -- 1.5 cfm/ft2
Barber 25 15
Beauty 25 25
Clothiers, furniture -- 0.30 cfm/ft2
Embalming roomb   2.0 cfm/ft2
Florist 8 15
Hardware, drug, fabrics 8 15
Nail salonb,i -- 50 cfm intermittent or 20 cfm continuous per station
Pet shops -- 1.00 cfm/ft2
Reducing salons 20 15
  Supermarkets 8 15
Sports and amusement    
Ballrooms and discos 100 25
Bowling alleys (seating areas) 70 25
Game rooms 70 25
Ice arenas -- 0.50 cfm/ft2
Playing floors (gymnasiums) 30 20
Spectator areas 150 15
  Swimming pools (pool and deck area) -- 0.50 cfm/ft2
Storage    
Repair garages, enclosed parking garaged -- 1.5 cfm/ft2
  Warehouses -- 0.05 cfm/ft2
Theaters    
Auditoriums 150 15
Lobbies 150 20
Stages, studios 70 15
  Ticket booths 60 20
Transportation    
Platforms 100 15
Vehicles 150 15
  Waiting rooms 100 15
Workrooms    
Bank vaults 5 15
Darkrooms -- 0.50 cfm/ft2
Duplicating, printing -- 0.50 cfm/ft2
Meat processingc 10 15
Pharmacy 20 15
Photo studios 10 15

For SI: 1 cubic foot per minute = 0.0004719 m3/s, 1 ton = 908 kg, 1 cubic foot per minutes per square foot = 0.00508 m3/(s•m2), °C = [(°F) -32]/1.8, 1 square foot - 0.0929 m2.
a. Based upon net floor area.
b. Mechanical exhaust required and the recirculation of air from such spaces as permitted by Section 403.2.1 is prohibited (see Section 403.2.1, Items 1 and 3).
c. Spaces unheated or maintained below 50°F are not covered by these requirements unless the occupancy is continuous.
d. Ventilation systems in enclosed parking garages shall comply with Section 404.
e. Where the ventilation rate is expressed in cfm/ft2, such rate is based upon cubic feet per minute per square foot of the floor area being ventilated.
f. The sum of the outdoor and transfer air from adjacent spaces shall be sufficient to provide an exhaust rate of not less than 1.5 cfm/ft2.
g. Transfer air permitted in accordance with Section 403.2.2.
h. Reserved.
i. The required exhaust system shall capture the contaminants and odors at their source.




[Statutory Authority: RCW 19.27.190, 19.27.020, and chapters 19.27 and 34.05 RCW. 07-01-092, § 51-52-0403, filed 12/19/06, effective 7/1/07. Statutory Authority: RCW 19.27.020, 19.27.031, 19.27.074 and chapters 19.27 and 34.05 RCW. 05-01-015, § 51-52-0403, filed 12/2/04, effective 7/1/05.]


NOTES:

     Reviser's note:  The brackets and enclosed material in the text of the above section occurred in the copy filed by the agency.