Where a hospital or nursing home facility which has previously received a special permit proposes to utilize, alter or modify any building or structure which is in existence on the date of the application for a new or amended special permit approval pursuant to this section, or where an existing hospital proposes to construct a new building or structure or addition thereto, the Planning Board, subject to appropriate conditions, may waive the requirements for minimum building setback, maximum height, total floor area, minimum lot frontage, maximum building coverage, required parking, and any such other dimensional regulation, standard or condition, including landscaping and buffering requirements, or other requirements as set forth in this chapter.