Controlling energy cost usually involves lowering the energy use or using lower-cost energy without negatively impacting operations, processes, safety and occupants' comfort. Because plants face a more-competitive market environment due to quick technological obsolescence, energy cost control is all the more important. Understanding the energy cost structure and identifying and monitoring key energy performance indicators should be the first step for any plant's energy engineer or energy manager. To reduce energy costs and sustain the improvements achieved, it's necessary to have a systematic approach that's reviewed periodically. The first step to this approach is generally an energy audit. Depending upon the final deliverable, an energy audit can have multiple scope levels. In this column we'll discuss the applicable deliverable levels of an energy audit.
Energy audits usually consist of two stages: a walk-through energy audit and a comprehensive review. The main goal of each is to review a plant's energy use; a report summarizes the audit results and compares utility use to that of "Best in Class" plants with similar processes to prioritize strategies that can reduce the overall cost of utilities.