Changes in energy intensity in the manufacturing sector 1985--1991

In this report, energy intensity is defined as the ratio of energy consumption per unit of output. Output is measured as the constant dollar of value of shipments and receipts, and two measures of energy consumption are presented in British thermal units (Btu): Offsite-Produced Energy and Total Inputs of Energy. A decrease in energy intensity from one period to another suggests an increase in energy efficiency, and vice versa. Energy efficiency can be defined and measured in various ways. Certain concepts of energy efficiency, especially those limited to equipment efficiencies, cannot be measured over time using changes in energy-intensity ratios. While improved energy efficiency will tend to reduce energy intensity, it is also true that a change in energy intensity can be due to factors unrelated to energy efficiency. For this report, energy intensity is used as a surrogate measure for energy efficiency, based on industry knowledge and current methodological analyses