Air-conditioners are going to be set up in public elementary schools. The installation rate reached 64% in Tokyo 23 wards in 2007. The increase of energy consumption is a concern as air-conditioner use spreads all over the country. In this study, the forecast of energy consumption until 2030 is illustrated. This is calculated by forecasting the number of classes in which air-conditioners have been installed and the air-conditioning load in each 47 prefectures. In addition, the energy-saving measures such as natural ventilation and Low-e glass are accounted. It is possible to reduce energy consumption to the level of 1990 by 2030, when all the measures and improvement in COP of air-conditioner are taken.