With the development of distributed generation (DG) technologies and the implementation of policies to encourage their applications, building combined heat and power (BCHP) is expected to play a greater role in the commercial buildings in the future. BCHP is a promising efficiency improvement and carbon mitigation strategy, but careful selection of technology and operation mode is required to achieve a reasonable system performance according to energy consumption characteristics of buildings and technical features of equipments. This paper analyzed energy consumption characteristics of four typical commercial buildings in Japan and simulated the energy system performances of four mostly widely adopted DG technologies under different operation mode conditions for the four buildings studied. Various scenarios were evaluated and compared regarding energy utilization efficiency, energy saving and environmental effects, as well as economic efficiency. Results show that the hotels and hospitals are more attractive for BCHP because of their stable thermal load demands and a favorable heat-to-power ratio, which is the most compatible match with available DG technologies. Furthermore, some DG technologies are more suitable for a certain type of building than others because of their technical features more matching with the building's energy consumption characteristics, as well as the user's motivation of selecting BCHP. In Japan,, during selecting DG technologies, the prior order is gas turbines (GT), gas engines (GE), diesel engines (DE) and phosphoric acid fuel cells (PAFC) for the hotels, PAFC, GE and GT, DE for the hospitals, PAFC, DE, GE and GT for the stores, as well as DE, PAFC, GE and GT for the offices. (C) 2009 Elsevier Ltd. All rights reserved.