Pohl, JohannaJohannaPohlSuski, PaulPaulSuskiHaucke, FranziskaFranziskaHauckePiontek, Felix M.Felix M.PiontekJäger, MichaelMichaelJäger2022-03-052022-03-052019https://publica.fraunhofer.de/handle/publica/25853610.1007/978-3-030-12266-9_1The way in which products and services are used can have a significant impact on their environmental performance. Practice shows, however, that life cycle assessment (LCA) studies often either assume average usage parameters, or only address a limited number of life cycle phases ('cradle to gate'), without considering the use phase. This chapter therefore aims to emphasize the relevance of user decision and behaviour in LCA and to discuss related modelling aspects with regard to the definition of system boundaries, the definition of the use phase and the collection of inventory data. Furthermore, processes of decision-making in the context of LCA are critically reflected and suggestions for improvements are discussed.en690book article