Fuel combustion for heat and/or electric power production is often the largest contributor of greenhouse gas (GHG) emissions from an industrial process plant. Economically feasible options to reduce these emissions include fuel switching and retrofitting the plant's energy system. Process integration methods and tools can be used to evaluate potential retrofit measures. For assessing the GHG emissions reduction potential for the measures considered, it is also necessary to define appropriate GHG emission baselines. This paper presents a systematic GHG emission calculation method for retrofit situations including improved heat exchange, integration of combined heat and power (CHP) units, and combinations of both. The proposed method is applied to five different industrial processes in order to compare the impact of process specific parameters and energy market specific parameters. For potential GHG emission reductions the results from the applied study reveal that electricity grid emissions are significantly more important than differences between individual processes. Based on the results of the study, it is suggested that for sustainable investment decision considerations a conservative emission baseline is most appropriate. Even so, new industrial CHP in the Northern European energy market could play a significant role in the common effort to decrease GHG emissions. (C) 2003 Elsevier Ltd. All rights reserved.