The provisions of this Zoning Bylaw governing the height of buildings shall not apply to chimneys, cooling towers, elevator bulkheads, skylights, ventilators, electronic equipment, elevator shafts and other necessary appurtenances usually carried above roofline, nor domes, towers, stacks or spires, if not used for human occupancy and which occupy not more than twenty (20) percent of the ground floor area of the building, nor to ornamental towers, observation towers, radio broadcasting towers, television and radio antennae and other like structures, which do not occupy more than twenty (20) percent of the lot area;