In the Commercial, Commercial-2, Office, Service Industrial, Highway Commercial, Neighborhood Commercial and Performance Zoning Districts, in addition to other signage allowed by this chapter or otherwise, businesses are permitted to display signage and flags signifying that a business is "open" in the following manner:
(a) One "open" sign on or within the building, not to exceed 2.5 square feet. This sign may be illuminated but must not be animated or flashing in any manner and must be turned off when the business is closed.
(b) One "open" flag not to exceed 15 square feet. This flag may be displayed on or within the building, or on the site provided that it meets all the signage height and setback requirements for the zoning district. This flag must be removed when the business is closed.