Skip Navigation
Postsecondary Education

NCES 2006-160
May 2006

4.2.2 Proration and Phantom Walls

Where a room serves several purposes or users, the institution may choose to prorate and allocate the square footage between two or more space uses, functions, organizational units, etc. For institutions with major sponsored research activities, proration of multiple use rooms may be necessary to identify accurately how each room is used. Proration can be done either on the basis of relative time expended on each activity or on the basis of the proportion of the area in the room dedicated to each activity.

There are two basic approaches to proration. One is to prorate by the insertion of “phantom walls” on floor plans, indicated by dashed lines as artificial boundaries to separate adjacent uses or assignments. The use of phantom walls requires that each space (i.e., each part of the room) be given a unique space identifier, which can be accomplished by adding an additional digit or character to the existing space identifier, and individual space use categories and organizational assignments. For example, Room 210, which is used as a Unit Storage (780) room by both Biology and Chemistry, could be identified as Space 210A, Unit Storage, Biology, and Space 210B, Unit Storage, Chemistry. This approach will prorate Room 210’s area correctly for each department, yet the space will be increased by one as we now have Spaces 210A and 210B replacing the former Room 210. Another method is to apply percentage figures to each use, function, etc., being prorated. This approach, requiring a more sophisticated database design, provides both an accurate proration of area and an accurate count of spaces. Whatever method is used, the resulting information should be capable of being summarized into standard space use codes and related categories for external reports, utilization studies, and institutional planning.