The legislative body of any municipality may, by ordinance, authorize such municipality to enter into a written agreement with an owner of any real property who agrees to improve, rehabilitate or renovate any building thereon to meet the standards of design and construction of the State Building Code to accommodate persons with physical disabilities, as set forth in article 512 of the State Building Code, or any subsequent corresponding section of the State Building Code, as from time to time amended, to fix the assessment on such property as of the date of the agreement for a period of not longer than five years and to defer any increase in assessment attributable to such improvement, rehabilitation or renovation during such period, provided (1) the agreement shall be approved by the local building official and (2) such improvement, rehabilitation or renovation shall be completed not later than three years from the date of the agreement and, upon completion, shall be subject to inspection and certification by such local building official as being in conformance with the applicable provisions of said code.