No land shall be used or occupied and no building hereafter erected, altered or extended shall be used or changed in use until a certificate of occupancy shall have been issued by the Zoning Enforcement Officer. Under such rules as may be established by the Board of Appeals, a temporary certificate of occupancy for not more than 30 days for a part of a building may be issued by the Zoning Enforcement Officer. For previously existing construction, the Zoning Enforcement Officer may, on request, issue such certificate if he determines that the use of the building in question meets the requirements of this chapter.