A variance shall normally be granted in perpetuity except that a change in the conditions justifying a variance shall be cause to reconsider the variance according to the procedure set forth in the foregoing sections. When the conditions justifying a variance are temporary, the commission or, on appeal, the city council may set a time after which the variance shall be null and void, and the property shall be subject to the regulations of the applicable zone classification.
(`64 Code, Sec. 34-158.5) (Ord. No. 917, 2367, 2445, 2445)