The development of a base-case process is a fundamental step in an energy efficiency study to obtain reliable results. However, this step is often overlooked and there are no clear guidelines for the systematic development of the base-case. A methodology has been proposed to properly define and evaluate the complete process for a subsequent in-depth energy analysis. It consists of two stages: definition and characterization of the process, and benchmarking analysis. In this paper, the first stage is presented. The base-case should encompass the process and the utilities systems, i.e., steam and water, as they are the driving forces of the chemical transformations. A four-pronged procedure is proposed to properly define and characterize a process and its utilities: data gathering, master diagram construction, utilities systems analysis, and simulation. The main objective is to build a computer simulation model to provide detailed information on production, distribution, utilization and post-utilization treatment of steam and water. Process inefficiencies are also identified, such as the low condensate recovery or the presence of non-isothermal mixing points. The procedure has been applied to an operating Kraft pulping mill in Eastern Canada. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.