Urban sewage source can be used as the cold and heat source for heat pump unit which consumes less electric energy to realize refrigerating and heating.

Take a 87,000m2 residential area for example, it is adjacent to a water company which disposes recycled water 120,000~150,000 tons a day which reaches the national A level emission standard, and the lowest temperature of the recycled water in winter is 10℃. Thus the sewage source heat pump system is suggested for the heating of the residential area. According to the actual conditions, the recycled water is pumped from the recycled water tank of the water company to the heat pump unit system, through heat exchanging process, to make 45℃ hot water for the heating.

The heat pump unit system was put into use in 2012 and it has been proven that the indoor temperature can reach above 20℃ during winter days, which gained good reputation. In 2014, the project developer continued to develop the third phase and the expected heating area is up to 500,000m2.