These days, there are many improvements of management situation for office buildings such as the change of air conditioning system, introduction of energy conservation systems and so on. Therefore it is predicted that an energy consumption of office buildings is changing. The purpose of this study is to clarify the tendency of energy consumption in the office buildings of Hiroshima city from 1991 to 2004 and to examine the relationship between the change of energy consumption and the factors which have an influence on the consumption such as outdoor air temperature of summer, density of number of workers, the renewal of air conditioning system and so on.
