Waiver of requirements. In the Central Business District, the required number of off-street parking spaces may be partially waived by the Zoning Hearing Board, provided satisfactory demonstration is made to the Board by the developer that the required number of such spaces is excessive for the use(s) proposed. In no case, however, shall any such waiver reduce the number of off-street parking spaces to less than 1/2 the number of spaces specified herein. Such waiver shall be permanent, and the Borough may not subsequently require the provision of the waived spaces; if, however, the use(s) change or enlarge, then the waiver shall become void pending reevaluation.