2.4.2. Environmental Function

As defined in the framework, functions are considered to be intended properties of the assessed system. For environmental functions this requires an explicitly specified positive impact on the environment. A very well-known biological example is mutualism, a relationship between different species with positive impact insofar as that both individuals benefit. The biological barter can be a resource-resource-relationship (e.g., mycorrhizal associations between plant roots and fungi) or a service-resource relationship (e.g., birds disperse plant seeds of fleshy fruits that they have eaten before) or a service-service-relationship (e.g., sea anemones and anemone fishes protect each other from their respective predators). In addition to these mutual relationships, a large number of closed material cycles (e.g., carbon cycle, nitrogen cycle, sulphur cycle and phosphorus cycle) are known, in which the starting material is finally available again through periodic transformation of chemical compounds.

Most technical systems do not have a specific environmental function and are consequently not assessed for this aspect. However, for systems which specifically intend to improve the accessibility of their wastes, such as waste treatment systems, or for systems that intend to transform their wastes to be suitable for others in a mutual form, the environmental function can be assessed and quantified. As the same system is investigated, the same assessment structure as for environmental burden is applied and defined as positive intended impacts. Life cycle related indirect effects such as recyclability in general are considered for burden assessment, as they are not regarded as intended design function [42].
