Fast economic growth in China has generated energy and environmental problems. Fixed-asset investments have contributed significantly to energy consumption. In China, an energy conservation assessment (ECA), a mechanism similar to the existing environmental impact assessment (EIA), has been applied to improve the energy efficiency of new fixed-asset investment projects. In this paper the origin and development of the ECA system is analyzed and the major features of ECA are discussed. To identify the success and failure of the ECA system, case studies are analyzed and comparison between ECA and EIA, which has been used in China for over 30 years, is made. Based on the analysis, recommendations are provided for the improvement of the ECA system in China. Despite the ECA system only being established for a relatively short time, it has clearly achieved significant success. With further efforts it could play an important role in achieving the goals of improving China's energy efficiency and reducing green house gas emissions. (C) 2012 Elsevier Ltd. All rights reserved.