Effective period. No order of the Village Board granting a variance shall be valid for a period longer than one year from the date of such order unless a building permit is obtained within such period and the erection or alteration of a building is started or the use is commenced within such period. Prior to expiration or within six months after the expiration of the original variance period, and any extensions thereto, the Village Board may grant extensions of this period, valid for one additional year, upon written application and good cause shown, without notice or hearing. These additional one-year time extensions shall commence on the date that any such extension is approved by the Board. If any of the benefits conferred by any variance, whether heretofore or hereafter granted, are abandoned, or are not utilized for any continuous period of one year, notwithstanding the above, said variance shall, to the extent of such abandonment or nonutilization, become invalid after a public hearing is provided herein.