(6-a) provides criteria whereby as an alternative to the hardship application provided under paragraph six of this subdivision owners of buildings acquired by the same owner or a related entity owned by the same principals three years prior to the date of application may apply to the division for increases in excess of the level of applicable guideline increases established under this law based on a finding by the commissioner that such guideline increases are not sufficient to enable the owner to maintain an annual gross rent income for such building which exceeds the annual operating expenses of such building by a sum equal to at least five percent of such gross rent. For the purposes of this paragraph, operating expenses shall consist of the actual, reasonable, costs of fuel, labor, utilities, taxes, other than income or corporate franchise taxes, fees, permits, necessary contracted services and noncapital repairs, insurance, parts and supplies, management fees and other administrative costs and mortgage interest. For the purposes of this paragraph, mortgage interest shall be deemed to mean interest on a bona fide mortgage including an allocable portion of charges related thereto. Criteria to be considered in determining a bona fide mortgage other than an institutional mortgage shall include; condition of the property, location of the property, the existing mortgage market at the time the mortgage is placed, the term of the mortgage, the amortization rate, the principal amount of the mortgage, security and other terms and conditions of the mortgage. The commissioner shall set a rental value for any unit occupied by the owner or a person related to the owner or unoccupied at the owner's choice for more than one month at the last regulated rent plus the minimum number