Asgar Khademvatani - Corresponding Author, I am a fourth year Ph.D. candidate at Department of Economics, the University of Calgary in Canada.
Daniel V., Gordon - Dr. Daniel V., Gordon is an Economics Professor, and my supervisor, at Department of Economics, the University of Calgary in Canada.
Alan J., MacFadyen - Dr. Alan J., MacFadyen is an Associate Professor, and my co-supervisor, at Department of Economics, the University of Calgary in Canada.

This study reviews the recent literature that has discussed energy intensity differences cross regions as a measure of energy efficiency. The paper encompasses most of the debates around energy efficiency by using energy intensity measure such as energy intensity decomposition, differences of energy intensity changes. We offer some evidence from a hybrid theoretical and empirical contributions by three groups of the literature related to subject. First, we expose the descriptive works that studied the historical energy efficiency policies in industrial countries, partly, in different sectors. Second, the applied econometric studies compared energy efficiency changes across nations. Finally, we review the energy efficiency literature related to data decomposition approach and data analysis methods. The main target of these studies is explaining gap of energy efficiency across nations and investigating whether the differences are becoming smaller or bigger. Comparing empirical results confirms declining and convergence of energy intensity over last half century cross- nations, but existence of energy intensity gaps. This study reports the reasons such energy prices, technology, fuel mix, etc as impacting factors on energy intensity changes. It also states some potential areas of improving energy efficiency. We conclude energy intensity is a misleading and ad hoc engineering measure of energy efficiency in the literature. We claim without an appropriate economic indicator of energy efficiency any debate around energy efficiency and the economy are premature and non-reliable. We find out that it is our position to measure energy efficiency by incorporating a microeconomics foundation and environment concerns as a dissertation.

Energy efficiency, energy intensity, convergence, energy productivity,microeconomics foundation