This study uses the dynamic data envelopment analysis model to evaluate the intertemporal efficiency and the executive efficiency based on fossil fuel CO₂ emissions in European Union countries. European Union countries in pursuit of economic growth, taking into account the growth of gross domestic product may result in increased CO₂ emissions, countries in order to reduce CO₂ emissions to meet the target of the UN climate change conference in Paris 2015, in pursuit of gross domestic product growth and CO₂ emission reduction targets. Whether the reduction of CO₂ emissions will affect the overall efficiency of the country’s economic growth or not will make gross domestic product a major consideration in carryover variables in this study. This paper analyzes data of 28 selected European countries dating from 2009 to 2013 to study the effects of the undesirable output to the energy efficiency ranking. The variables in the model are the input variables: labor force, real capital stock, and energy consumption and the output variable is the undesirable output of fossil fuel CO₂ emissions. In the model, the carryover intermediate activity is real gross domestic product. After the Paris Protocol formally replaced the Kyoto Protocol in 2015, the emphasis of this study is on the future state’s pursuit of economic growth, the gross domestic product as a variable in terms of intertemporal efficiency and using CO₂ as a variable of undesirable output to analyze the relationship between national economic development and the greenhouse gas emissions for getting a policy indicator of the environmental protection and economic development.

China’s rapid economic growth is accompanied by increasing energy consumption and severe environmental problems. As sustainable development can only be achieved by reducing energy intensity, new energy and renewable energy investment, as well as improving traditional energy efficiency, is becoming increasingly important. However, past energy efficiency assessments using data envelopment analysis (DEA) models mostly focused on radial and non-radial DEA model analyses. However, traditional radial DEA models ignore non-radial slacks when evaluating efficiency values, and non-radial DEA models ignore the same proportionality as radial DEA when evaluating efficiency value slacks. To balance the radial and non-radial model characteristics and consider undesirable output, this study combines a modified Epsilou-based measure (EBM) DEA and undesirable output and proposes a modified undesirable EBM DEA model to analyze the efficiency of China’s new and traditional energy sources. The empirical results found that (1) most new energy investment in most municipalities/provinces rapidly grew from 2013 to 2016; (2) as the annual efficiency score was only 1 in Beijing, Inner Mongolia, Shanghai, and Tianjin, the other 26 municipalities/provinces need significant improvements; (3) traditional energy efficiency scores were higher than new energy efficiency; and (4) NO₂ efficiencies are slightly better than CO₂ and SO₂ efficiencies.