N.Y.C. Admin. Code § 27-753: § 27-753 Index for ventilation.

The index for ventilation for any room or space shall be computed by adding the following:

(a) The contents per occupant, in cubic feet.

(b) The floor area per occupant, times ten, in square feet.

(c) The clear, unobstructed openable area of windows, skylights, and other sources of natural ventilation per occupant times two hundred, in square feet. In all cases, the number of occupants used in computing the index for ventilation shall be the maximum number who will occupy the room or space simultaneously during any two-hour period.