In all districts, other than C8 Districts, all energy infrastructure equipment and accessory mechanical equipment located below the rooftop level, other than solar or wind energy systems or equipment with a depth limited to 18 inches from an exterior wall, shall be subject to the following provisions when not located within a completely enclosed building, whether or not such equipment is located within a required open space, yard, or court:

1. all generators and cogeneration equipment utilizing fossil fuels which are accessory to buildings other than single- or two-family residences shall be completely enclosed within a building or other structure, except as necessary for mechanical ventilation;
2. all other types of equipment, including generators and cogeneration equipment serving single- or two-family residences, may be unenclosed, provided that such equipment is located at least five feet from any side or rear lot line and where located between a street wall, or prolongation thereof, and the street line, such equipment is within three feet of a street wall; and
3. where the area bounding all such equipment, as drawn by a rectangle from its outermost perimeter in plan view, exceeds 25 square feet, such equipment shall be screened in its entirety on all sides. Such screening may be opaque or perforated, provided that where perforated materials are provided, not more than 50 percent of the face is open.