In order to upgrade the energy efficiency ratio of a local district, the energy existed in the district is desired to be introduced. In this report, the district heating and cooling plant in Sunport Takamatsu employing the temperature difference of sea water which represents one of the unused energy was surveyed for one year. Then the energy consumption when the plant is not utilized with unused energy was estimated to compare the energy consumption of the systems with and without employing unused energy to determine energy saving effect. In addition, the practically effective energy ratio in consideration with the existing volume of the low temperature unused energy being conventionally employed was obtained to indicate a reference value in planning to employ the low temperature unused energy in future.
