According to statistics and field investigation, the energy consumption situation and reality of commercial building is described in this paper. As the first step of large-scale public building energy efficiency supervision system encouraged by central government of China, the energy consumption of several typical commercial buildings and public buildings was analyzed in detail. The main contents of investigation are as follows: basic information of building, operational record of energy consumption equipment, energy consumption of indoor equipments, energy-efficiency assessment of energy consumption systems and equipments, investigation of behavior energy saving, etc. On this basis further analysis and diagnosis including indoor thermal and humid environment, operation state of air-conditioning water system, operation state of air-conditioning duct system and operation management of air-conditioning system were implemented. The results show that the most energy consumption of buildings in this city is commercial buildings, which can reach to about 240 W/m(2) per year. Further analysis tells that air conditioning systems play the major role of building energy consumption, and building energy saving has great potential in this city. In this paper, the ways of diagnosis work for building energy consumption are also described and discussed. Reasonable test, diagnosis and analysis are meaningful for building energy efficiency retrofit and management. (C) 2008 Elsevier Ltd. All rights reserved.