Industrial Energy Use Indices



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Energy use index (EUI) is an important measure of energy use which normalizes energy use by dividing by building area. Energy use indices and associated coefficients of variation are computed for major industry categories for electricity and natural gas use in small and medium-sized plants in the U.S. The data is very scattered with the coefficients of variation (CoV) often exceeding the average EUI for an energy type. The combined CoV from all of the industries considered, which accounts for 8,200 plants from all areas of the continental U.S., is 290%. This paper discusses EUIs and their variations based on electricity and natural gas consumption. Data from milder climates appears more scattered than that from colder climates. For example, the ratio of the average of coefficient of variations for all industry types in warm versus cold regions of the U.S. varies from 1.1 to 1.7 depending on the energy sources considered. The large data scatter indicates that predictions of energy use obtained by multiplying standard EUI data by plant area may be inaccurate and are less accurate in warmer than colder climates (warmer and colder are determined by annual average temperature weather data). Data scatter may have several explanations, including climate, plant area accounting, the influence of low cost energy and low cost buildings used in the south of the U.S. This analysis uses electricity and natural gas energy consumption and area data of manufacturing plants available in the U.S. Department of Energy?s national Industrial Assessment Center (IAC) database. The data there come from Industrial Assessment Centers which employ university engineering students, faculty and staff to perform energy assessments for small to medium-sized manufacturing plants. The nation-wide IAC program is sponsored by the U.S. Department of Energy. A collection of six general energy saving recommendations were also written with Texas manufacturing plants in mind. These are meant to provide an easily accessible starting point for facilities that wish to reduce costs and energy consumption, and are based on common recommendations from the Texas A&M University IAC program.