For unit districts, needed capacity under Section 151.50(c) of this Part shall be calculated separately for elementary grades (pre-kindergarten through eight) and secondary grades (nine through twelve), with a needed capacity that is a negative number being treated as zero. In making these calculations, available capacity for a building that contains both elementary and secondary grades shall be considered either elementary or secondary capacity, depending upon whether a majority of the building's students are elementary or secondary students. The district's needed capacity shall be the sum of the elementary and secondary needed capacities.
Ill. Admin. Code tit. 23, § 151.55