The purpose of this study is to demonstrate an analytical method that can be used to incorporate development in industrial sub-sectors in national energy systems modelling analysis. The method is illustrated by a case study of the Swedish forest industry. The case study consists partly of a detailed industrial sub-sector scenario analysis of the Swedish forest industry and partly of an analysis of the usefulness of incorporating such a detailed treatment of the industry in energy system modelling analyses. The sub-sector analysis results in calculated energy and material flows for each scenario. The energy systems analysis results in a comparison of modelling results for the Nordic energy system, with and without the more detailed sub-sector analysis of the Swedish forest industry. Copyright (C) 2002 John Wiley Sons, Ltd.