The purpose of this study is to clearify the possibility of diffusion of District Heating and Cooling (DHC) in Japan in the near future and its effects on global environment preservation. We selected potential supplied areas of DHC in all over Japan by analyzing heating, cooling and hot-water demand character. We investigated the sourrounding unused energy of the selected areas and analyzed its effect. As a result, total DHC demand is 259,933TJ/a (62,185Tcal/a), that is quivalent to 11.1% of total demand in Japan. By using unused energy as heat sources, 88,733TJ/a (21,228Tcal/a) of primary energy consumption and 1.78 mil.ton of CO_2 emission can be reduced per year in Japan. It means that the DHC promotion is very important and realistic policy in urban area for CO_2 emission which contributes to global environment preservation.
