A market-irrelevant product property is a characteristic of a product that does not affect customer preferences and therefore does not influence product substitutability, but may nevertheless influence the reference flow. These properties represent attributes that, whilst technically distinguishing one product from another, do not drive consumer choice or alter the competitive position of products in the marketplace.
In Life Cycle Assessment, understanding which product properties are market-irrelevant is particularly important for consequential modelling approaches. When assessing how markets respond to changes in demand, only market-relevant properties determine which products will be substituted or displaced. Market-irrelevant properties, by definition, do not affect these substitution patterns.
However, even though these properties do not influence market behaviour, they can still affect the reference flow as defined in ISO 14040. The reference flow is the "measure of the outputs from processes in a given product system required to fulfil the function expressed by the functional unit." A market-irrelevant property might require a different quantity of product to deliver the same functional unit, even though customers treat the products as equivalent for purchasing decisions.
Examples of market-irrelevant product properties include the geographic location where a product was manufactured (when this does not affect price, quality, or delivery time perceived by customers), specific production technologies that produce identical products, or certain packaging characteristics that do not influence consumer selection. In contrast, properties such as price, quality, brand reputation, or functional performance typically are market-relevant because they directly influence customer preferences and purchasing behaviour.
The distinction between market-relevant and market-irrelevant properties becomes crucial when determining which activities in a product system should be included in consequential LCA. Only changes in market-relevant properties will trigger market responses and affect which products are actually displaced or substituted in the economy.
