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]

For spaces with operable openings on one side of the space, the distance from the operable openings shall be not more than 2H, where H is the ceiling height. [ASHRAE 62.1:6.4.1.1]

For spaces with operable openings on two opposite sides of the space, the distance from the operable openings shall be not more than 5H, where H is the ceiling height. [ASHRAE 62.1:6.4.1.2]

For spaces with operable openings on two adjacent sides of a space, such as two sides of a comer, the distance from the operable openings shall be not more than 5H 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]

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]