The complexity of the Life Cycle Assessment (LCA) method requires many subjective choices throughout the procedure, which make decision making difficult and LCA results insecure. Our approach consists in combining life cycle thinking and sensitivity analysis to provide information to the actor of a foreground system within a product's life cycle. For any parameter of a foreground system, the trends and quantified influence on impact categories are systematically compared to determine the most effective action levers for actors controlling the process. This approach has been previously applied to a single actor, the farmer, in a case study of hemp crop production. In this study, we introduce a second life cycle actor: the industrial producer for transformation of hemp straw into insulation products for buildings. The relationships between farming and industrial actors are examined and demonstrate that industrial actors have action levers limited to climate change and energy consumption. Only a joint action of both actors can allow further reduction of climate change and energy consumption impacts. Nevertheless, the farmer action alone can allow reduction of other environmental impacts such as human toxicity or ecotoxicity.