For all new development or redevelopment of freestanding buildings, not part of the previously built shopping center, not less than 2% of the total gross acreage of new lots shall be designated as and devoted to usable open space in the form of pedestrian gathering areas, such as parklets in the range of 400 to 500 square feet, courtyards in the range of 500 to 2,000 square feet, plazas in the range of 2,000 to 3,000 square feet, and other pedestrian gathering areas of 3,000 square feet or more, located in close proximity to the new buildings and lots.