The enactment of this title shall not terminate or otherwise affect rights, variances and permits acquired or authorized under the provisions of any section hereby revised or repealed. Where a building permit and a zoning certificate have been issued for the construction of a building or structure, and for an authorized use and occupancy thereof, in accordance with the law prior to the effective date of this revised ordinance, said building or structure may be completed in conformance with the approved plans and on the basis for which the said building permit and zoning certificate had been issued, provided construction of said building or structure is commenced within sixty (60) days of the effective date of the building permit and diligently prosecuted to completion. Detailed conditional use applications based upon concept plans approved prior to the effective date of this revised ordinance shall be subject to the terms and conditions of this revised ordinance. Upon showing an undue hardship, an applicant may be allowed by the planning and zoning commission to process such detailed conditional use applications under the terms and conditions of the previous ordinance. (2003 Code § 11-01-01.4)