All buildings that exceed a height of 170 feet shall provide articulation in accordance with at least one of following provisions:

(a)        Setbacks on each tower face

The highest three stories, or as many stories as are located entirely above a height of 170 feet, whichever is less, shall have a lot coverage of at least 50 percent of the story immediately below such stories, and a maximum lot coverage of 80 percent of the story immediately below such stories. Such reduced lot coverage shall be achieved by one or more setbacks on each face of the tower, where at least one setback on each tower face has a depth of at least four feet, and a width that, individually or in the aggregate, is equal to at least 10 percent of the width of such respective tower face. For the purposes of this paragraph (a), each tower shall have four tower faces, with each face being the side of a rectangle within which the outermost walls of the highest story not subject to the reduced lot coverage provisions have been inscribed. The required setbacks shall be measured from the outermost walls of the building facing each tower face. Required setback areas may overlap.

(b)        Three setbacks

Setbacks shall be provided at the level of three different stories, or as many stories as are located entirely above a height of 170 feet, whichever is less. Such setbacks shall be located on either the north-facing or south-facing side of the building, but not both. Such setbacks shall have a minimum depth of 15 feet measured, as applicable, from the north-facing or south-facing wall of the story immediately below. For towers with at least six stories located entirely above a height of 170 feet, the lowest level at which such setbacks may be provided is 170 feet, and the highest story, therefore, shall be located entirely within the northern or southern half of the tower, as applicable.

(c)        Reverse setbacks

A minimum of 15 percent of the area of the plane surface of street walls enclosing floor area of the tower and a maximum of 50 percent of the area of the plane surface of the street walls enclosing floor area of the tower shall project at least 18 inches but not more than five feet from the remaining plane surface of the street walls enclosing any floor area of the tower. No projections, including balconies, shall be permitted from the lowest two stories of the tower.