Energy in manufacturing facilities is used for direct production of goods, space conditioning, and general facility support such as lighting. This paper presents a methodology, called lean energy analysis, LEA, for graphically and statistically analyzing plant energy use in terms of these major end uses. The LEA methodology uses as few as 60 easily obtainable data points. Multivariable change-point models of electricity and natural gas use as functions of outdoor air temperature and production data are developed. The statistical models are used to subdivide plant energy use into facility, space-conditioning and production-related components. These breakdowns suggest the savings potential from reducing non-production and space-conditioning energy use. In addition, graphical analysis of the statistical models and data promotes the discovery of energy saving opportunities. Finally, the models can be used to predict energy use for energy budgeting, measure savings, determine cost structures, and for diagnostic purposes. Case study examples demonstrate the lean energy analysis method and its application.