4.2. Design Process

A typical engineering design process starts with a set of vague needs related to a set of (societal) problems and ends in a well defined engineering design solution. The starting point is a problematic situation that needs improvement.

In Chapter 2 the formal generic process has been described. In this section a more formal description is used that will be useful when comparing the engineering design process to the processes of decision making, systems thinking and optimization.

A designer is normally given a program of requirements that needs to be transformed into a design solution. The step from the program of requirements to design solution requires creativity from the designer’s point of view. Formally the designer will come up with a design configuration of characteristics of the new object.

Take the case of a building where the designer needs to think about the number of floors, the size and layout of different types of spaces, the types of materials used for the different building components, etc. The designer will search for a configuration that best meets the program of requirements.

The program of requirements is a representation of the different goals that stakeholders want satisfied and is an expression of the required fitness for purpose. It could be that the floor size of function A needs to be at least \(X\) square meters, that the energy consumption cannot exceed \(Y\) kWh, that the costs cannot exceed \(Z\) euro, etc.

The program of requirements can be considered a set of design constraints that are directly related to the different goals that the stakeholders want optimized. Floor sizes need to be maximized, energy consumption needs to be minimized, costs need to be minimized, etc.

Apart from the requirements that normally relate to stakeholders, the designer also needs to take into account a range of limitations. These limitations can relate to rules and regulations or the laws of physics. The amount of material for a steel beam is proportional to its length. When too little material is used the beam will not be able to carry the load that it is expected to carry. The number of floors of a building is proportional to its height and cannot violate rules set by the municipality.

Note the distinction between rules and regulations and the laws of physics. Formally, rules and regulations are not fixed and can change over time because they relate to human desirability. Contrary, laws of physics do not change over time and are fixed and cannot be violated. Of course a new theory with regards to the laws of physics could mean that an existing law needs to be changed but that change has nothing to do with human desirability.