402.2 Natural Ventilation. Natural ventilation systems

shall be designed in accordance with this section and shall include mechanical ventilation systems designed in accordance with Section 403.0, Section 404.0, or both. Exceptions: (1) An engineered natural ventilation system where approved

by the Authority Having Jurisdiction need not comply

402.2.1.1 Single Side Opening. For spaces with operable openings on one side of the space, the distance from the operable openings shall be not more than 2 H, where H is the ceiling height. [ASHRAE 62.1:6.4.1.1] 402.2.1.2 Double Side Opening. For spaces with operable openings on two opposite sides of the space, the distance from the operable openings shall be not more than 5 H, where H is the ceiling height.

[ASHRAE 62.1:6.4.1.2]

(1) An engineered natural ventilation system where approved

by the Authority Having Jurisdiction need not comply with Section 402.2. (2) A mechanical ventilation system is not required where:

(a) natural ventilation openings comply with the require ments of Section 402.2 and are permanently open or

(a) natural ventilation openings comply with the require ments of Section 402.2 and are permanently open or have controls that prevent the openings from being closed during periods of expected occupancy or (b) the zone is not served by heating or cooling equip ment. [ASHRAE 62.1:6.4]

(b) the zone is not served by heating or cooling equip ment. [ASHRAE 62.1:6.4] 402.2.1 Floor Area to Be Ventilated. Spaces, or portions of spaces, to be naturally ventilated shall be located within a distance based on the ceiling height, in accordance with Section 402.2.1.1, Section 402.2.1.2, or Section 402.2.1.3, from operable wall openings in accordance with Section 402.2.2. For spaces with ceilings which are not parallel to the floor, the ceiling height shall be determined in accordance with Section 402.2.1.4. [ASHRAE 62.1:6.4.1]

2019 CALIFORNIA MECHANICAL CODE 63

VENTILATION AIR any other purpose or distributed to any other persons or parti es.

402.2.1.3 Corner Openings. For spaces with operable openings on two adjacent sides of a space, such as two sides of a corner, the distance from the operable openings shall be not more than 5 H along a line drawn between the two openings that are farthest apart. Floor area outside that line shall comply with Section 402.2.1.1. [ASHRAE 62.1:6.4.1.3] 402.2.1.4 Ceiling Height. The ceiling height, H, to be used in Section 402.2.1.1 through Section 402.2.1.3 shall be the minimum ceiling height in the space. Exception: For ceilings that are increasing in height as distance from the openings is increased, the ceiling height shall be determined as the average height of the ceiling within 20 feet (6096 mm) from the operable openings. [ASHRAE 62.1:6.4.1.4] 402.2.2 Location and Size of Openings. Spaces, or portions of spaces, to be naturally ventilated shall be permanently open to operable wall openings directly to the outdoors, the openable area of which is a minimum of 4 percent of the net occupiable floor area. Where openings are covered with louvers or otherwise obstructed, openable area shall be based on the net free unobstructed area through the opening. Where interior rooms, or portions of rooms, without direct openings to the outdoors are ventilated through adjoining rooms, the opening between rooms shall be permanently unobstructed and shall have a free area of not less than 8 percent of the area of the interior room nor less than 25 square feet (2.3 m ² ).

[ASHRAE 62.1:6.4.2] 402.2.3 Control and Accessibility. The means to open required operable openings shall be readily accessible to building occupants where the space is occupied. Controls shall be designed to coordinate operation of the natural and mechanical ventilation systems. [ASHRAE 62.1:6.4.3]