Energy simulation was conducted for office buildings in the five major climate zones - severe cold, cold, hot summer and cold winter, mild, and hot summer and warm winter - in China using DOE-2.1E. The primary aim was to investigate the thermal and energy performance of office buildings with centralised heating, ventilation and air conditioning plants in the major climatic zones in China. The computed results were analysed in three aspects - heating load, cooling load and the corresponding building energy consumption. The building peak monthly heating load varied from 142 MW h (1033 MW h cooling) in Hong Kong to 447 MW h (832 MW h cooling) in Harbin. It was also found that passive solar designs could have large energy savings potential in the severe cold and cold climates. In Harbin, the window solar component helped lower the annual building heating load by 650 MW h. Internal loads (lighting and office equipment) and part load operations of fans and pumps also played a significant role in the overall building energy efficiency. This paper presents the work, its findings and energy efficiency implications. (C) 2008 Elsevier Ltd. All rights reserved.