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Design by Separation

Closely related to design by inversion1), design by separation is based on separating functions that may typically exist in a single part or assembly2).

Separation in time

Separate functions that would normally occur together or in parallel, so that they occur individually, or in series.


  • A new topic comes up during a meeting, unrelated to the agenda of the meeting: schedule a separate meeting to treat the new topic.
  • A roadway without sufficient space to accommodate all traffic, may be altered to permit traffic in only one direction at specific times of day.

Separation in space

Separate physically things that exist in the (approximately) same position or location.


  • Set aside a meeting space for any impromptu meeting with more than two participants, so as not to disturb other workers.
  • Move computer desktop windows apart on a screen so that dissimilar information is distinct.
  • Roadways that may intersect may be separated vertically (over/under-passes).

Separation on condition

Separate functionality into sub-functions such that the actual function required can only occur when elements are properly combined.


  • A variety of poisons and explosives work this way; e.g. two otherwise inert materials become extremely volatile when mixed together. A peaceful use of this is in rocket fuel.
  • Crayola has made a type of crayon that only draws on special paper. This means the crayons cannot write on walls.
  • In road design, one might consider a programmable and movable median barrier that moves to accommodate different amounts of traffic in each direction, based on the amount of traffic.
Design by inversion can be thought of as separating and exchanging functional elements between two product components.
These techniques can also be derived from principles of TRIZ.
design/design_by_separation.txt · Last modified: 2020.03.12 13:30 (external edit)