The embodied energy/CO 2 of buildings in China and Japan, which reflects the characteristic industrial efficiency of building materials, is described in this paper. The energy consumption and CO 2 intensities for the dominant materials used in buildings are derived from the energy consumption in factories, and the energy consumption to produce equipment is derived from IO (input/output) analysis in order to compare the embodied energy/CO 2 for buildings between China and Japan based on the same estimation method. Although the energy consumption of structures in China is two to three times greater than in Japan, the interior finish and air conditioning equipment, for example, are simpler and smaller. As a result, the embodied energy/CO 2 of office buildings in China is only 10% to 20% greater than that of Japanese office buildings. Thus, the embodied energy/CO 2 of buildings depends on both industrial efficiencies and building design trends of the country.