An obligatory product property is a characteristic or attribute that a product must possess in order to be considered by a customer or market as a relevant option for product substitution. These properties define the minimum requirements that make a product functionally acceptable as an alternative to another product in the same market or application.
In Life Cycle Assessment, particularly in consequential LCA modelling, identifying obligatory product properties is essential for determining which products can realistically substitute for one another when market conditions change. Not all products with similar functions can substitute for each other in practice, as customers often have specific requirements that must be met before they will consider a product as a viable alternative.
Obligatory product properties differ from optional or desirable properties in that they represent non-negotiable requirements. For example, in the construction materials market, a cement substitute must meet minimum strength specifications to be considered for structural applications. Whilst additional properties such as colour or setting time might be desirable, they are not obligatory for the product to be considered as a potential substitute.
These properties are closely related to the concept of the functional unit in ISO 14040, which defines the quantified performance of a product system. However, obligatory product properties go beyond the functional unit specification by identifying the minimum market acceptance criteria that determine substitutability in real-world economic scenarios.
Understanding obligatory product properties is particularly important when applying system expansion or identifying marginal suppliers in consequential LCA. Products that share the same obligatory properties compete in the same market segment and can therefore displace one another when demand changes. Products lacking one or more obligatory properties, even if functionally similar in other respects, operate in different market segments and cannot be considered as direct substitutes.
The identification of obligatory product properties requires understanding customer requirements, market standards, regulatory requirements, and technical specifications that define product categories within specific industries and applications.
