The Board of Zoning Appeals may authorize upon appeal in specific cases such variance from the terms of this Ordinance as will not be contrary to the public interest where, owing to special conditions, a literal enforcement of the provisions of this Ordinance would result in unnecessary hardship. No non-conforming use of neighboring lands, structures, or buildings in other districts shall be considered grounds for issuance of a variance. Variances shall not be granted on the grounds of convenience or profit, but only where strict application of the provisions of this Ordinance would result in unnecessary hardship.