This paper contains the methodological and empirical results of an investigation into the energy consumption characteristics of a GM manufacturing plant. In examining the energy portfolios of a particular plant, two statements can be made concerning the energy sources. Their level of utilization should be: a) directly correlated, in some degree, to endogenous variables such as direct labor hours, production volume, degree days, etc., and b) impacted significantly by any “visible” change in the composition of the technologies, the physical aspects of the work environment, and the labor force. The question to be answered is “which variables are directly related to energy consumption?” In answer to that query, a model constructed to account for future energy is usage, by source, within the manufacturing environment. Data was collected from eight plants for a twenty-eight month time period. Results for the models are given by two criteria, R2 and the standard error of the estimate as a percent of the response mean.