Multifunctionality and Allocation

Many processes produce more than one useful output: a wastewater plant delivers clean effluent and may also yield biogas, sludge for agriculture or recovered nutrients. Allocation is the rule for sharing the plant’s impacts among those outputs. ISO 14044 sets an order of preference: avoid allocation by dividing the process or by expanding the system first, then partition by physical relationships, and only then by other relationships such as economic value.