(a) There shall be allowed to each district with attendance units of 300 or more in kindergarten and grades 1 to 6, inclusive, a maximum area of 55 square feet for each attendance unit of the district in kindergarten and grades 1 to 6, inclusive.
(b) The maximum total building area per attendance unit allowed to applicant districts with attendance units of less than 300 in kindergarten and grades 1 to 6, inclusive, for such attendance units shall be determined by the board, and shall be building area to provide comparable facilities to those provided by subdivision (a) of this section, and shall be the least building area required to house adequately the estimated average daily attendance and the normal instructional and other services.