## 5 Discussion and Conclusions  
This study analyzes the spatial differences in energy intensity between the G20 countries from both aggregate and sectoral levels. A country's energy intensity can be expressed as a weighted sum of the EEI of each sector. Multiplicative SDA was used to further analyze the driving factors of spatial differences in energy intensity at the aggregate and sectoral levels. The impact of the input structure effect on the EEI of key sectors differs between these countries. The results indicate the following. (1) The gap in aggregate energy intensity among the G20 countries tended to converge from 2000 to 2014. At the regional level, the energy consumption intensity of the G20 countries varies greatly from region to region. Developed countries such as the United States and those in European countries have higher energy efficiency, while post-industrial countries such as Russia, China, and India have lower energy efficiency. Reducing energy intensity in Russia, India, China, and South Korea has great potential to reduce global energy consumption and improve global energy efficiency. In 2014, the EEI of 21 key industries in Russia, 17 in India, 19 in China, and 18 in South Korea were higher than the average level of the corresponding industries' average of the G20 countries. (2) With other factors remaining the same, the sectoral energy intensity effect leads to above-average energy intensity levels in the five highest-energy-intensity countries except Indonesia. In Russia, China, and Indonesia, the above-average energy intensity levels are caused by the input structure effect. Furthermore, the final demand structure effect causes the energy intensity of high-energy-consuming countries to be higher than the G20 average. The main driving force for the above-average energy intensity in India, South Korea, and Canada is the sectoral energy intensity effect, in Russia and China it is the input structure effect, and in Indonesia it is the final demand structure effect. (3) Taking the average of the G20 countries as a reference, after the theoretical optimization of the sectoral energy intensity effect, input structure effect, and final demand structure effect of six high-energy-intensity countries, the embodied energy consumption of these countries decreases. Among them, China, Russia, and India will reduce their embodied energy consumption by 62.75 EJ, 31.94 EJ and 21.24 EJ, respectively. The EEI decline in six high-energy-intensity countries is equivalent to 21.78% of the G20's total energy consumption in 2014. Thus, reducing the energy intensity of the G20 countries, especially China, Russia, and India, has great potential for reducing the global energy consumption. (4) The EEI drivers of national key industries with high energy consumption intensity in the G20 countries were decomposed into the sectoral energy intensity effect and input structure effect. The sectoral energy intensity effect is the most important factor that leads to the EEI of key industries in India and South Korea being higher than the average levels of the corresponding industries in the G20 countries. For Russia and China, the input structure effect is the most important factor. Given the above conclusions, we offer the following suggestions. (1) The reduction in energy intensity of the G20 countries should focus not only on production-side management, but also on demand-side governance. It should trace all indirect industrial links behind the direct links and fully depict the driving effects of final demand on each industry's energy consumption. When these countries participate in the international division of labor, it would be beneficial for them to shift production to value chains with relatively low energy consumption and relatively high added value. This shift will help reduce the energy intensity of these countries. (2) The G20 countries should optimize each country's aggregate final demand structure and intermediate input structure as well as improve energy efficiency.