Modelling and analysing lifecycle environmental impacts of product systems demands often specialized knowledge and is time-demanding. Product systems are typically defined by complex technical foreground systems and immersed in highly diverse contexts and background systems. Available software tools fail to streamline the modelling and analysis of this complexity, leading to extensive iterations or rough simplifications. The approach introduced in this paper supports the modelling of complex systems and their interactions with diverse backgrounds. This enables developing flexible and comprehensive environmental assessment tools. The applicability and advantages of the approach developed is demonstrated through its application for the environmental assessment of electric vehicles.