Chimneys, flues, church spires, belfries, cupolas, parapet walls, flagpoles, fire towers, water towers and all other necessary mechanical appurtenances and similar features, but excluding telegraph, radio and television transmission or other antennas, shall be exempt from the height provisions of this chapter, provided that:
(1) The height of each such feature shall not exceed three feet above the actual height of such roof.
(2) The aggregate area covered by all such features, but excluding solar heating features, shall not exceed 15% of the area of the roof of the building of which they are a part.
(3) Purely architectural embellishments for purposes of providing light, such as atrium roofs or skylights, shall also be permitted, provided that the same do not exceed a height of five feet above the finished roof, and provided that the same do not occupy, in addition to the other appurtenances heretofore allowed by this section, more than 20% of the roof area.
(4) The exterior treatment of all such mechanical penthouses and other projections also permitted herein shall be of materials substantially similar to the facade of the building itself and shall be similarly designed so as to be architecturally an integral part of the structure. The determination of compliance with all aspects of this section shall be by the approving authority as a function of site plan approval.