Industrial energy systems are complicated networks where changes in one process influence itsneighboring processes. The network complexity increases if production/use of bio fuel is introduced in anexisting system. Process integration can be a useful tool to study such systems and thus avoid sub optimization.However, changes in an industrial complex do not only influence the technical values of energy and materialefficiency. The social impact is also important and sometimes is comparable to that of technical factors.A process integration project has recently been carried out for a paper mill in northern Sweden with a side viewon future expansion with a bio refinery. An activity to study the social impacts were included through a Conjointanalysis, a stated preference method that combines statistics and interviewing technique.The results indicate that the participants are divided in four groups, the largest group focusing on a change in theprocess towards a bio refinery, the second largest focusing on the local environment. The third and fourth groupboth look at the local forestry, one group wanting to increase local forest production, and one rejecting anincrease.