Section 27-765. Ventilation for schools

School buildings shall be ventilated
  in accordance with the following requirements:
    (a)  Rooms  of instruction and administration. Classrooms, other rooms
  of  instruction,  and  administrative  rooms,  where   the   index   for
  ventilation  is  less  than one thousand six hundred fifty, shall have a
  supply of  outdoor  air  of  at  least  fifteen  cfm  per  occupant  and
  mechanical exhaust.  Where windows are used as the source of supply air,
  mechanical  air  exhaust shall be fifteen cfm per occupant. When outdoor
  air is supplied by mechanical means,  the  exhaust  shall  be  at  least
  eighty per cent of the supply. In air-conditioned rooms, the conditioned
  air supply may be reduced to a minimum of ten cfm per occupant, of which
  at least five cfm shall be outdoor air.
    (b) Lockers and wardrobes. Lockers, wardrobes, or wardrobe rooms shall
  be  ventilated  in  accordance  with the provisions of section 27-760 of
  this article, and where these spaces are located within or  adjacent  to
  classroom,  the  exhaust  air  from  the  classroom may be used for such
  ventilation.
    (c) Auditoria and assembly rooms. Rooms  where  there  are  more  than
  seventy-five  occupants  shall  have a supply of outdoor air of at least
  fifteen cfm per occupant and mechanical exhaust. Where windows are  used
  as  the  source  of supply air, mechanical air exhaust shall be at least
  fifteen cfm per occupant. When outdoor air  is  supplied  by  mechanical
  means,  the  mechanical exhaust shall be at least eighty per cent of the
  supply. In air-conditioning spaces, the conditioned air  supply  may  be
  reduced to a minimum of ten cfm per occupant, of which at least five cfm
  shall be outdoor air.