Extensive work exists on value in multiple domains. However, there are different interpretations, highlighting a lack of clarity about the fundamental characteristics. To address this, we present seven value axioms resulting from inductive research. The axioms may be viewed as general rules describing value in any context, therefore conveying the fundamental characteristics of the phenomenon. They reveal that value is: (1) connected to people; (2) an output of a cognitive process; (3) in requirement of a determination process; (4) a matter of a given situation; (5) determined by the interpretations of entities; and related to (6) entities and (7) criteria. The nature of value is of particular importance to the design community, given the emphasis on value in design and product development. In this context, a lack of clarity may be perceived in terms of when value appears, appropriate metrics, and how to add value. To provide explanations, there is a need for a theory of value in design. The presented axioms may provide the basis, as they are fundamental statements on the nature of value and not limited to a specific domain. We highlight theory requirements based on the axioms.

In spite of the increasing importance placed on the creation and delivery of value, it is unclear what value is and how it is determined in design. In this paper, the first descriptive model of value determination (ValueD) is presented to clarify the key elements and mechanisms involved. ValueD describes value determination as a cognitive process that is situated and dependent on an agent's knowledge. The variables involved are: an entity interpreted by an agent; a situation of an agent; knowledge of an agent; a criteria prioritisation activity; a criteria selection activity; and a criteria judgement activity. The output of the value determination process is a value statement. Value is shown to refer to a judgement on the extent an interpreted entity satisfies an agent's criteria. The ValueD model is evaluated through comparison against seven axioms of value and a protocol analysis of an engineering design episode. The article concludes with a discussion of strengths, limitations, and future work on ValueD, and its relationship with key value concepts such as added value, exchange and perceived value, benefit, and need.