Consumption is an Activity that you cannot have others do for you, as opposed to Production (work). This fundamental distinction rests on Margaret Reid's third party criterion, which provides a practical test for categorising human activities: if you could reasonably contract or commit another person to perform an activity on your behalf, it qualifies as production; if the activity must be performed by you personally to deliver its value, it qualifies as consumption.
Examples of consumption activities include physical exercise, enjoying art, eating, sleeping, and attending social and religious events. These activities are inherently personal and cannot be delegated whilst retaining their value or purpose. You cannot, for instance, have someone else exercise on your behalf and expect to gain the fitness benefits, nor can you delegate the enjoyment of a meal or the experience of attending a social gathering.
In the context of Life Cycle Assessment, consumption represents the use phase within a product life cycle, where products deliver their intended function directly to end users. Whilst ISO 14040 and 14044 do not explicitly define consumption using Reid's criterion, the standards recognise consumption activities as part of the broader category of human activities that occur within product systems. Understanding the distinction between consumption and production is essential for properly modelling product systems, as consumption activities represent the ultimate purpose for which products are manufactured and distributed.
This economic definition of consumption differs from colloquial usage, where "consumption" might simply mean "using up" resources. In Life Cycle Assessment and economic analysis, consumption specifically refers to those activities that directly contribute to human wellbeing and cannot be outsourced to third parties.
