Concept design is the stage of designing where function is embodied with technologies and behavioural principles.
Concept design is a major design activity that maps function to behaviour in the context of a given situation. It is the part of designing that is classically known as the “creative step” of developing a design intervention; it is both the most “fun” part - because you can let your creativity run wild - and the most difficult part - because there is no way to guarantee the development of a truly creative, innovative solution.
Colton & Pun (1994) [CP94] write that concept design is the “…cognitive and behavioral process by which needs are identified and defined, a sufficient variety of concepts or ideas for satisfying that need is created, and initial screening is completed.” This is broader than what most other experts say, removing the identification and definition of needs to some kind of problem analysis stage.
A primary goal of engineering design is to map function to form (as broadly described elsewhere). Behaviour is used as an intermediary step, since behaviour is both tied to form, and used to provide function in specific situations. Thus, concept design is the crucial step from function to behaviour.
Concept design also relates to systems, because a system provides functions to its supersystem according to its internal behaviours described by subsystems.
There are, generally, a very large number of combinations of behaviours that can provide a given set of functions. The goal of concept design is to search the space of combinations of behaviours for the best possible combination.
It is usually impossible to find the absolute best design concept. If it were possible, then everyone would drive the same kind of car, write with the same kind of pen, and sit in the same kind of chair.
Exercise for the reader: How many different reasons can you think of to explain our inability to find the absolute best design?
Instead, we try to find a concept that is, in some quantifiable way, “better” (though often not by much) than other comparable, existing designs.
The real question becomes: What does it mean to say one product is “better” than another? How is “better” defined? Does “better” mean different things to different people?
This brings us back to the importance of users and requirements, and reinforces the need to deeply understand those earliest parts of the design process.
To perform concept design, you need as precise as possible an understanding of the nature of the situation, the imbalances that you need to address, and what transformations (of inputs to outputs) your design intervention will need to perform.
The following steps are executed to perform concept design:
Because of coevolution and the system hierarchy that develops over the course of a design project, it is important to remember that one instance of the concept design task is limited to one system at one level of the system hierarchy. It is often the case that design concepts may include features that cannot be justified because they exist at a lower level of the system hierarchy. One must pay attention to only design within the bound of the current level of the hierarchy; otherwise, the unjustifiable decisions that result will very likely result in a weaker overall design.