In order to obtain a variance, the applicant bears the burden of showing that: (1) the variance will not be contrary to the public interest; (2) special conditions exist such that literal enforcement of the zoning ordinance results in unnecessary hardship; (3) the variance is consistent with the spirit of the zoning ordinance; (4) substantial justice is done; and (5) granting the variance will not diminish the value of surrounding properties. Harrington v. Town of Warner, 152 N.H. 74, 77, 872 A.2d 990 (2005) (citing Shopland v. Town of Enfield, 151 N.H. 219, 222, 855 A.2d 392 (2004)). The third criterion analyzed was whether denial of the variance would result in unnecessary hardship (excluding financial hardship) to the owner. Id. The unnecessary hardship standard has been further defined by the holding in Boccia v. City of Portsmouth, 151 N.H. 85, 855 A.2d 516 (2004). The Supreme Court distinguished between use and area variances when determining whether an applicant has established unnecessary hardship. Harrington v. Town of Warner, 152 N.H. 74, 77-78, 872 A.2d 990 (2005). "The superior court is obligated to treat the factual findings of the planning board as prima facie lawful and reasonable and cannot set aside its decision absent unreasonableness or an identified error of law." Summa Humma Enterprises, LLC v. Town of Tilton, 151 N.H. 75, 79, 849 A.2d 146 (2004). "The review by the superior court is not to determine whether it agrees with the planning board's findings, but to determine whether there is evidence upon which they could have been reasonably based." Id. (citing Lone Pine Hunters' Club v. Town of Hollis, 149 N.H. 668, 670 (2003)).