Environmental performances of products largely influence performances of systems. The objective of this work is to propose an approach on how to aggregate product level environmental assessment results to obtain system level assessments. The life cycle assessment methods considered at the product level will be relevant for the use in different European policies (Ecodesing, Energy Labels, Green Public Procurement and Ecolabel). The work that I am carrying out in the European Commission is related to the environmental assessment of several product groups for its use in product policies. Thus, these case studies could be the basis for proposing case studies which will be used to validate the proposed approach of the PhD. Two base cases are first foreseen : the system taps/showers - boilers and the system refrigeration-insulation components of a refrigerator. For example in the first case, taps/showers and boilers are connected products. The performances of these two product categories are linked so that the improvement of either the boiler and/or the taps/showers can affect the whole environmental performance in different ways. The environmental performance of the individual products and the system will consider the whole life cycle and will be multi criteria : consumption of resources, environmental impacts (including water scarcity), resource efficiency, etc. Examples of environmental assessment methods potentially used for calculating the environmental performance of products and systems in this work could be Life Cycle Assessment, Product Environmental Footprint, Resource efficiency of products methodology, etc.