In this subtitle the following words have the meanings indicated. “Fund” means the Rental Housing Fund established under § 4–504 of this title. “Household of limited income” means one or more individuals who occupy the same residential dwelling unit and whose total household income does not exceed the upper income limits established by the Secretary for the Program under § 4–404 of this subtitle. “Office or other commercial space conversion” means the conversion to rental housing of a building that: is in a sustainable community as defined in § 6–301 of this article; was built more than 30 years before an application is submitted to the Department to finance the conversion; consists of at least two floors at or above ground level; and was last used as office or other commercial space. “Program” means the Rental Housing Program. “Rental housing project” means a project eligible for financial assistance under § 4–407 of this subtitle.