Procedures are described in which economies can be effected through careful planning of school buildings and particularly through the consolidation of spaces that are used intermittently throughout the school day. The paper introduces a "use-factor" as a measure, not of the amount of usable space but of the time for which usable space is actually utilized during the school day. Assembly spaces, science rooms, workshops, and circulation spaces are considered with regard to their employment for a multiplicity of purposes. A bibliography listing books concerning multi-purpose rooms is included. (FS)