In this project aims at using thermal energy from the sewage system for heating and cooling buildings in the management office. The advantages of sewage is high value as a heat source. The temperature of the effluent of the wastewater treatment plant varies from 8 to 20 ℃ and thus contains thermal energy. When compared to air heat source is considered to be in good condition. In this study first analyzed the characteristics of the effluent characteristics located in Yong-in City, the last three years of data Giheung-Reseupiah. The sewage heat recovery system was designed using a heat pump as much as possible to reduce energy. We will analyze the cooling and heating performance of the experimental data. Finally, we are going to find the optimum operational conditions of economic and efficient.