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The intake opening which draws air from the outside atmosphere shall be located at a point that prevents contamination of the air supply and shall be unobstructed at all times. The intake opening shall be located not less than 15 feet from the discharge outlet of any exhaust fan, plumbing vent and chimney or similar object. Unless adequate means are provided to remove dust from the air, the bottom of the intake opening shall be not less than 10 feet above the surface of any abutting public way, gangway, driveway, grade, or abutting roof. No intake opening shall be placed in a horizontal position in any sidewalk, or in the pavement of any street, alley, or driveway, or within 12 inches of the level of any other surrounding grade; nor shall any intake opening take air from the lower level of any two-level street or similar construction. In loading docks, intake openings shall be located not less than 10 feet horizontally or vertically from any loading dock door.
Exceptions:
1. Interior loading spaces and appurtenant driveways. No ventilation openings for loading spaces and appurtenant driveways shall be required if the following conditions are met:
1.1 Loading spaces and appurtenant driveways are used in manufacturing, storage or mercantile units;
1.2 Doors open directly to the outside atmosphere at each loading space;
1.3 The loading dock is raised at least 36 inches above the adjacent driveway;
1.4 The doors are situated no more than 65 feet from the dock; and
1.5 The dock area is separated from the interior of the unit by a wall or door or by both.
2. No ventilation openings for exterior loading spaces and appurtenant driveways shall be required if the following conditions are met:
2.1 The loading dock is constructed with the floor of the dock not less than 36 inches above the adjacent driveway; and
2.2 The driveway is not enclosed; and
2.3 At least 20 percent of the lineal footage of the total external wall of the dock or 50 percent of the lineal footage of the largest external wall of the dock consists of loading doors.
The air removed by every mechanical ventilating exhaust system shall be discharged outside at a point where it will not cause a nuisance, and from which it cannot again be readily drawn in by a ventilating system.
Exceptions:
1. Air which will not cause a nuisance may be discharged into a boiler room in such quantity as is required to supply the needs of combustion.
2. Air which will not cause a nuisance may be discharged into a garage used for active storage of only five or more cars, provided the garage is separately ventilated during all hours of occupancy, in accordance with the provisions of Section 18-28-403.3.
2.1 Provisions shall be made in cases as described above so that when an air system is used for smoke exhaust, the smoke shall be automatically discharged to the outside and the secondary use of the air is automatically dampered off.
Air intake and exhaust that terminate outdoors shall be suitably protected against Chicago weather conditions, with corrosion resistant screens, louvers and grilles. Area of the outside air intake shall be sized so that at least 100 percent of the code-required outside air as required in Section 18-28-403.1 can be taken from outside at velocities not in excess of 1,000 feet per minute (304.8 mpm) through free area except for systems defined in paragraph 18-28-403.1.3.
Outdoor Opening Type | Minimum and Maximum Opening Sizes in Louvers, Grilles and Screens Measured in Any Direction |
Exhaust openings | Not less than 1/4 inch and not greater than 1/2 inch |
Intake openings in residential occupancies | Not less than 1/4 inch and not greater than 1/2 inch |
Intake openings in other than residential occupancies | Not less than 1/4 inch and not greater than 1 inch |
For SI: 1 inch = 25.4 mm.
If the air condition in any habitable room becomes objectionable due to causes other than the occupancy by human beings, and the Building Commissioner finds that the health and comfort of the human occupants is endangered, additional ventilation by natural or mechanical means shall be provided in accordance with Article 5, Exhaust Systems, or as approved by the Building Commissioner.
Natural ventilation shall comply with Chapter 12 of the Chicago Building Code.
(Amend Coun. J. 4-10-19, p. 100029, Art. XII, § 3; Amend Coun. J. 9-14-21, p. 35949, Art. IV, § 2)
The air supply for every ventilation system, either natural or mechanical, shall be taken from out of doors, except in the following situations:
Exceptions:
1. Recirculation. When air is supplied by a mechanical ventilating supply system, a portion of the code required air supply may be recirculated, provided the system is equipped with such devices for control of temperature and dust content in the spaces to be ventilated and that the conditions of the air so supplied, (except as to temperature) are substantially the same as though all of the supply air were taken from out-of-doors. Under such conditions, not less than thirty-three and one-third percent of the Code requirements shall be taken from out-of-doors by the mechanical ventilating supply system; and sixty-six and two-thirds percent of the code requirements may be recirculated air, plus any additional air volume of system design capacity in excess of code requirements.
2. When air is supplied by a mechanical ventilating supply system which is not equipped with devices prescribed in paragraph 1, then only such portions of the air volumes of the system design capacity in cfm that exceed the total code requirements in cfm may be recirculated during the time of room occupancy. The air intake and all equipment and ducts shall be so arranged that all of the code required air supplied by the system can be taken from outside, with provisions made for release or exhaust of such air to the atmosphere.
3. Prohibited exhaust. No air exhausted from bath, toilet, urinal, or similar room, lavatory, locker, coat room, kitchen, boiler room, or rooms of similar use in which such air might be contaminated by smoke, gases, or dust which might be noxious, dangerous, or detrimental to health shall be recirculated at any time; except that air exhausted from locker and coat rooms or kitchens may be recirculated when unoccupied.
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