In any case where the applicant alleges that floor area is an inappropriate measure of the extent of damage or destruction, and elects to substitute reconstruction costs for floor area, an application may be made to the Board of Standards and Appeals to determine the extent of the damage or destruction. Such a building may be reconstructed as provided in Section 54-41 (Permitted Reconstruction), substituting the ratio which the cost of reconstructing the damaged or destroyed portion of such building bears to the cost of reconstructing the entire building, for the percentage of total floor area. In determining reconstruction costs, the cost of land shall be excluded.