Nothing in this Development Code shall prohibit the completion of the construction and use of buildings for which a Zoning Certificate or Building Permit has been issued prior to the effective date of this Development Code, or amendments thereto, provided construction shall start within one (1) year of the issuance of the Zoning Certificate or Building Permit is carried on diligently and without interruption and the entire building shall be completed within one (1) year after the start of construction. Actual construction is hereby defined to include the placing of construction materials in permanent position and fastened in a permanent manner. Where demolition or removal of an existing building has begun preparatory to rebuilding, such demolition or removal shall be deemed to be actual construction.