A note: Will tomorrow's energy efficiency indices prove useful in economicstudies?

Recent attempts to construct national energy efficiency indices begin with the construction of "Btu aggregates" which are developed by adding together different energy resources based on their heating potential values or the heating values of the primary energy resources used to produce the energy r esources which are ultimately consumed. The resulting indices may be of lim ited use in economic studies, where it is often important to consider the r elative economic value of various component resources and their substitutab ility in response to relative price changes. In such applications, Btu aggr egates will tend to suggest greater achievements in energy efficiency durin g periods of electrification than would an approach which aggregates differ ent energy resources based on their market values.