In this subtitle the following words have the meanings indicated. “Affected property” means: a residential rental property constructed before 1950 that contains not more than one rental dwelling unit; or a residential rental property that contains not more than one rental dwelling unit for which the owner makes an election under § 6–803(a)(2) of the Environment Article; or an individual rental dwelling unit within: a residential rental property constructed before 1950 that contains more than one rental dwelling unit; or a residential rental property that contains more than one rental dwelling unit for which the owner makes an election under § 6–803(a)(2) of the Environment Article. “Affected property” does not include property exempted under § 6–803(b) of the Environment Article. “Owner” has the meaning stated in § 6–801(o) of the Environment Article. “Rental dwelling unit” has the meaning stated in § 6–801(u) of the Environment Article.